The inhaled pharmacotherapy is fundamental in the management of obstructive lung diseases such as asthma bronchiale or chronic obstructive pulmonary disease. In this context short- and long-acting β2-agonists play a prominent role as relieve and control medication. Regarding the risk-benefit profile of an inhaled drug, the pattern of pulmonary deposition and the rate and extent of absorption into systemic circulation are essential parameters. New developments of drugs are characterized by high lung retention and improved efficacy. The aim of the present thesis was the parallel evaluation the pharmacokinetic (PK) and -dynamic (PD) properties of inhaled β2-agonists employing an isolated human lung perfusion model (IPL). The short-acting β2-agonist salbutamol and the newly developed ultra long-acting β2-agonist GW597901 were chosen for the analysis of pulmonary drug absorption and bronchodilation. In a pharmacokinetic enabling study an established human IPL setting was modified to monitor the pharmacokinetics of the β2-agonists by measuring the concentrations in perfusion fluid, lung tissue and BAL samples obtained during and after the experiments. The IPL model revealed differences in the pulmonary absorption behaviour of GW597901 and salbutamol. The lipophilic compound GW597901 was distributed to a lower extent into the perfusion fluid compared to the more hydrophilic compound salbutamol. The analyzed time profiles of nebulized salbutamol in the perfusate were consistent to with a clinical study if considering experimental conditions as the actual deposited doses and the differing volume of distribution. Thus, the suitability of the IPL model for the PK analysis of inhaled β2-agonists was confirmed. In a PK/PD study the human ex vivo model was employed for the first time for the evaluation of the clinical relevant bronchodilating effect induced by inhaled β2-agonists in addition to the analysis of their pharmacokinetics. Thereby the focus was to determine the onset and extent of bronchodilation. A new method was established to monitor changes in lung function parameters due to pharmacodynamic interventions over the duration of the experiment that allowed permanent online recording of the ventilation volume and lung mechanic parameters. Bronchial challenges with aerolised MCh were performed successfully in isolated ventilated human lung lobes, even though the responder rate was lower than expected despite high administered doses. The administration of the short acting agent salbutamol led to an immediate onset of action recognized as a sudden increase of the ventilation volumes. The bronchodilation following the application of GW597901 was observed delayed after about 6 min. Monitored lung function parameters considerably improved by both β2 - agonists in the IPL setting but not significantly different. Thus, in regard of the different applied doses GW597901 had a higher intrinsic activity and bronchodilating potency than salbutamol. The concentrations of salbutamol and GW597901 in the perfusate determined in the PK/PD study were significantly lower than those observed in the pharmacokinetic enabling study, while the tmax values and the course of the distribution profiles remained similar. Most likely, the application of nebulized MCh prior to the administration of the β2 - agonists had a substantial influence on their pharmacokinetic behaviour. It is yet not clear whether pharmacodynamic effects or molecular competition processes for the passage to the systemic circulation or both influenced the redistribution of the β2 - agonists as seen in the PK/PD study. The potential clinical relevance of this observation has to be further investigated. The development of pulmonary edema during the experiment was one limitation of the IPL model. For the determination of the onset of edema formation four potential biochemical markers, specifically surfactant-protein A (SP-A), angiotensin-converting enzyme (ACE), urea and lactate dehydrogenase, were measured in perfusion fluids. In this context, an ELISA method for the quantification of human SP-A in biological matrices was successfully established. The investigations showed that the concentrations of SP-A and ACE in the perfusate increased over time as a sign for lung tissue damage and correlated with the degree of edema formation. For the first time the IPL model was used for the evaluation of potential pulmonary edema marker and the results have shown that it is valuable tool for further investigations in this field. In conclusion, the pharmacokinetic and pharmacodynamic characterization of GW597901 and salbutamol was successfully achieved using the IPL model. This ex vivo methodology may contribute to further insights and understanding of the complex pharmacokinetic processes of inhaled β2 – agonists in the lung. / Die Inhalationstherapie stellt den grundlegenden Baustein in der Behandlung obstruktiver Lungenerkrankungen wie Asthma bronchiale oder chronisch obstruktiver Lungenerkrankung dar. Eine essentielle Rolle spielen dabei kurz- und langwirksame β2 – Agonisten, die sowohl als Bedarfs- und Kontrollmedikation eingesetzt werden. Bei Betrachtung des Nutzen-Risiko-Verhältnisses eines inhalativen Arzneistoffes sind das pulmonale Depositionsmuster und die Geschwindigkeit und das Ausmaß, mit welcher der Arzneistoff in die systemische Zirkulation gelangt, von zentraler Bedeutung. Das Ziel dieser Arbeit war die Bestimmung pharmakokinetischer (PK) und -dynamischer (PD) Eigenschaften inhalativer β2 – Agonisten anhand des isolierten humanen Lungenperfusionsmodells (IPL). Der kurzwirksame β2 – Agonist Salbutamol und der neue langwirksame Vertreter GW597901 dienten dabei als Modellsubstanzen für die Analyse der pulmonalen Absorption und den Effekt der Bronchodilatation. In einer ersten Versuchsreihe wurde das etablierte IPL Modell derart modifiziert, um mittels gemessener Konzentrationen in der Perfusions- und Lavageflüssigkeit sowie in Lungengewebsproben die Pharmakokinetik von β2 – Agonisten zu bestimmen. Das IPL Modell zeigte Unterschiede im pulmonalen Absorptionsverhalten von GW597901 und Salbutamol. Der lipophile Vertreter GW597901 wurde in geringerem Ausmaß in die Perfusionsflüssikeit umverteilt als das hydrophile Salbutamol. Das analysierte Absorptionsprofil von Salbutamol korrelierte dabei sehr gut mit Daten einer Humanstudie, wenn man die experimentellen Bedingungen wie die tatsächlich deponierte Dosis und das abweichende Verteilungsvolumen berücksichtigte. Dadurch war die Eignung des IPL Modells zur PK Analyse inhalativer β2 – Agonisten bestätigt. Zusätzlich zur Betrachtung der PK wurde das humane IPL Modell nun zum ersten Mal zur Untersuchung des klinisch relevanten Effekts der Bronchdilatation der β2 – Agonisten herangezogen. Dabei sollten vor allem der Beginn und das Ausmaß der induzierten Bronchodilatation bestimmt werden. Es konnte erfolgreich eine neue Methode etabliert werden, die es erlaubte durch permanente online Aufzeichnung von Ventilationsparameter Änderungen in der Lungenfunktion darzustellen, die durch pharmakodynamische Interventionen ausgelöst wurden. Erstmals wurde erfolgreich eine bronchiale Provokation an einem ex vivo ventilierten humanen Lungenlappen durchgeführt. Jedoch war trotz hoher verabreichter MCh Dosen die Responderrate niedriger als erwartet. Die Applikation des kurzwirksamen Vertreters Salbutamol führte zu einem sofortigen Effekt. Der Wirkeintritt der Bronchodilatation verursacht durch GW597901 war hingegen um ungefähr 6 Minuten verzögert. Unter Berücksichtigung der unterschiedlichen verabreichten Dosen zeigen diese Ergebnisse eine höhere intrinsische Aktivität und atemwegserweiternde Wirksamkeit von GW597901 im Vergleich zu Salbutamol. Die analysierten Konzentrationen von GW597901 und Salbutamol im Perfusat waren in der PK/PD Studie signifikant niedriger als diejenigen, die in der vorherigen PK Versuchsreihe gemessen wurden, während die jeweiligen Tmax Werte und Umverteilungsprofile unverändert blieben. Die wahrscheinlichste Erklärung hierfür ist, dass die Applikation von MCh vor der Vernebelung der β2 – Agonisten einen erheblichen Einfluß auf deren pharmakokinetischen Verhalten hatte. Gegenwärtig kann nicht mit Sicherheit eine Aussage darüber getroffen werden, ob pharmakodynamische Effekte, Konkurrenzmechanismen um die Aufnahme in den systemischen Kreislauf auf molekularer Ebene oder beides zu einem veränderten Umverteilungsverhalten der β2 – Agonisten in der PK/PD Studie geführt haben. Die Entwicklung von Lungenödemen im Verlauf der Experimente war eine Einschränkung des IPL Modells. Um den Beginn einer Ödembildung besser bestimmen zu können, wurden vier potenzielle biochemische Marker in Perfusatproben untersucht, das Surfactant Protein-A (SP-A), das Angiotensin-konvertierende Enzym (ACE), Harnstoff und das Enzym Lactatdehydrogenase (LDH). Die Untersuchungen haben gezeigt, dass die Konzentrationen von SP-A und ACE im Perfusat über die Zeit als Anzeichen für eine Lungengewebsschädigung in Korrelation zum Ausmaß der Ödembildung anstiegen. Zum ersten Mal wurde das IPL Modell für die Bestimmung von biologischen Markern für pulmonale Ödementstehung herangezogen und die Ergebnisse haben gezeigt, dass dieses ex vivo Modell einen vielversprechenden Ansatz für weitere Untersuchungen in diesem Bereich bietet. Damit konnten erfolgreich Methoden entwickelt werden, um mit Hilfe des humanen IPL Modells die pharmakokinetischen und -dynamischen Eigenschaften von GW597901 und Salbutamol zu charakterisieren. Die angewandte ex vivo Methodik kann hierbei einen wertvollen Beitrag und weiterführende Erkenntnisse zum besseren Verständnis der komplexen pharmakokinetischen Vorgänge inhalativer β2 – Agonisten leisten.

Beta 2 glycoprotein I (β2GPI) is a major antigenic target in antiphospholipid syndrome (APS). In vitro studies suggest that it may have multifaceted physiological functions, as it displays both anticoagulant and procoagulant properties. Beta 2GPI may bind to FXI and serve as a regulator of FXI activation by thrombin. The possible interaction of β2GPI with thrombin is investigated using enzyme linked immunosorbent assays and surface plasmon resonance based studies. It is demonstrated for the first time that domain V of β2GPI is involved in direct binding to thrombin, and exosites I and II on thrombin take part in this interaction. It is also shown that cleavage of β2GPI at Lys317-Thr318 does not interrupt this binding. A quaternary complex is proposed on the surface of activated platelets in which β2GPI may colocalise with FXI and thrombin to regulate FXIa generation. The effect of anti-β2GPI monoclonal antibodies (mAbs) were investigated on this system using 8 anti-β2GPI mAbs directed against domain I. Anti-β2GPI Abs potentiate the suppressing activity of β2GPI on FXI activation by thrombin. Moreover, they restore the inhibitory effect of clipped β2GPI on this system. The current study demonstrates for the first time a novel biological consequence of thrombin interaction with β2GPI. The effect of β2GPI on thrombin inactivation by the serine protease inhibitor heparin cofactor II (HCII) is investigated using chromogenic assays, platelet aggregation studies, and the platelet release response. The current work shows that β2GPI protects thrombin from inactivation by HCII/Heparin. This ability is modulated by the cleavage of β2GPI. A ternary structure is proposed between β2GPI, thrombin and heparin which may limit the N-terminus of HCII to exosite I therefore inhibit thrombin inactivation by HCII. The effect of anti-β2GPI Abs is examined in this system using patient polyclonal IgGs and a murine anti-β2GPI mAb. Anti-β2GPI Abs potentiate the protective effect of β2GPI on thrombin inhibition by HCII/Heparin. In view of the importance of HCII in regulating thrombin activity within the arterial wall, disruption of this function by β2GPI/anti-β2GPI Ab complexes may be particularly relevant in arterial thrombosis in APS. Beta 2 glycoprotein I (β2GPI) is a major antigenic target in antiphospholipid syndrome (APS). In vitro studies suggest that it may have multifaceted physiological functions, as it displays both anticoagulant and procoagulant properties. Beta 2GPI may bind to FXI and serve as a regulator of FXI activation by thrombin. The possible interaction of β2GPI with thrombin is investigated using enzyme linked immunosorbent assays and surface plasmon resonance based studies. It is demonstrated for the first time that domain V of β2GPI is involved in direct binding to thrombin, and exosites I and II on thrombin take part in this interaction. It is also shown that cleavage of β2GPI at Lys317-Thr318 does not interrupt this binding. A quaternary complex is proposed on the surface of activated platelets in which β2GPI may colocalise with FXI and thrombin to regulate FXIa generation. The effect of anti-β2GPI monoclonal antibodies (mAbs) were investigated on this system using 8 anti-β2GPI mAbs directed against domain I. Anti-β2GPI Abs potentiate the suppressing activity of β2GPI on FXI activation by thrombin. Moreover, they restore the inhibitory effect of clipped β2GPI on this system. The current study demonstrates for the first time a novel biological consequence of thrombin interaction with β2GPI. The effect of β2GPI on thrombin inactivation by the serine protease inhibitor heparin cofactor II (HCII) is investigated using chromogenic assays, platelet aggregation studies, and the platelet release response. The current work shows that β2GPI protects thrombin from inactivation by HCII/Heparin. This ability is modulated by the cleavage of β2GPI. A ternary structure is proposed between β2GPI, thrombin and heparin which may limit the N-terminus of HCII to exosite I therefore inhibit thrombin inactivation by HCII. The effect of anti-β2GPI Abs is examined in this system using patient polyclonal IgGs and a murine anti-β2GPI mAb. Anti-β2GPI Abs potentiate the protective effect of β2GPI on thrombin inhibition by HCII/Heparin. In view of the importance of HCII in regulating thrombin activity within the arterial wall, disruption of this function by β2GPI/anti-β2GPI Ab complexes may be particularly relevant in arterial thrombosis in APS.

An outline of the work contained in this thesis is presented. The first chapter is a critical review of the literature pertaining to the pathophysiological mechanisms operational with regards to the antiphospholipid syndrome (APS). The syndrome is characterised by venous and arterial thrombosis, and recurrent fetal loss, in association with the persistent presence of antibodies targeting the main autoantigen beta 2-glycoprotein I (β2GPI). The second chapter reviews the literature delineating the diverse physiological functions of β2GPI, and then relates them to its role in our current understanding of the pathophysiology of APS. The third chapter presents a critical review of the evidence base for the diagnosis and management of APS. The fourth chapter describes the interaction between β2GPI and the glycoprotein Ib alpha (GPIbα) subunit of the platelet receptor GPIb-IX-V. GPIbα is an important platelet adhesion receptor, which mediates multiple additional functions on the platelet surface, including binding coagulation factor XI (FXI). The implication of the interaction between β2GPI and GPIbα on platelet activation and the release of thromboxane in the presence of anti-β2GPI antibodies is explored, as well as the intracellular pathways via which this activation occurs. The relevance of these findings to understanding APS pathogenesis, in particular thrombosis, is discussed. The fifth chapter delineates the interaction between the fifth domain of β2GPI and FXI and its activated form factor XIa (FXIa). The ability of FXIa to cleave β2GPI between lysine (Lys) 317 and threonine (Thr) 318, and modulate its function is reported. The sixth chapter describes the ability of β2GPI to inhibit FXIa autoproteolytic hydrolysis at the specific FXIa residues arginine (Arg) 507, Arg532 and Lys539. This interaction with β2GPI stabilizes FXIa activity over time, and leads to enhanced FXIa mediated fibrin formation. This is a novel physiological function of β2GPI with important implications. Recent epidemiological studies by others have emphasized the critical role of FXIa in pathological thrombus propagation. The seventh chapter defines the relevance of the FXIa residues Arg507, Arg532 and Lys539 to FXIa mediated inactivation by the main FXIa inhibitor Protease Nexin 2 (PN2), and by Antithrombin III (ATIII). Insights into future directions for research are presented and discussed within each individual chapter.

G protein coupled receptors, G proteins and their downstream effectors adenylyl cyclase (ACs) were thought to transiently interact at the plasma membrane by random collisions following agonist stimulation. However a growing number of studies have suggested that a major revision of this paradigm was necessary to account for signal transduction specificity and efficiency. The revised model suggests that signalling proteins are pre-assembled as stable macromolecular complexes together with modulators of their activity prior to receptor activation. How and where these signalling complexes form and the mechanisms governing their assembly and maintenance are not completely understood yet. Initially, we addressed this question by exploring AC2 interaction with beta2-adrenergic receptors (beta2ARs) and heterotrimeric G proteins as parts of a pre-assembled signalling complex. Using a combination of biophysical and biochemical techniques, we showed that AC2 interacts with them before it is trafficked to the cell surface in transfected HEK-293 cells. These interactions are constitutive and do not require stimulation by receptor agonists. Furthermore, the use of dominant-negative Rab/Sar monomeric GTPases and dominant-negative heterotrimeric G protein subunits proved that AC2/beta2AR and AC2/Gbetagamma interactions occurred in the ER as measured using both BRET and co-immunoprecipitation experiments, while interaction of the Galpha subunits with the above complexes occurred at a slightly later stage. Both Galpha and Gbetagamma played a role in stabilizing these complexes. Our data also demonstrated that stimulation of AC was still possible when the complex remained on the inside of the cell but was reduced when the GalphaS/AC2 interaction was blocked, suggesting that the addition of the GalphaS subunit was required to render the nascent complexes functional prior to trafficking to proper sites of action. Next, we tackled the issue of higher order assembly of effectors and G proteins, using two different AC isoforms and GalphaS as a model. We demonstrated that AC2 can form heterodimers with AC5 through direct molecular interaction in unstimulated HEK-293 cells. AC2/5 heterodimerization resulted in a reduced total level of AC2 expression, which affected cellular accumulation of cAMP upon forskolin stimulation. The AC2/5 complex was stable in presence of receptor or forskolin stimulation. We provided evidence that co-expression with GalphaS increased the affinity of AC2 for AC5 as monitored by BRET. In particular, the complex formed by AC2/5 lead to synergistic accumulation of cAMP in presence of GalphaS and forskolin, with respect to either of the parent AC isoforms themselves. Finally, we also showed that this complex can be detected in native tissues, as AC2 and AC5 could be co-immunoprecipiated from lysates of mouse heart. Taken together, we provided evidence for stable formation of signalling complexes involving receptor/G proteins/adenylyl cyclase or G proteins/heterodimeric adenylyl cyclases and that G proteins play a crucial role for their assembly and function.

An outline of the work contained in this thesis is presented. The first chapter is a critical review of the literature pertaining to the pathophysiological mechanisms operational with regards to the antiphospholipid syndrome (APS). The syndrome is characterised by venous and arterial thrombosis, and recurrent fetal loss, in association with the persistent presence of antibodies targeting the main autoantigen beta 2-glycoprotein I (β2GPI). The second chapter reviews the literature delineating the diverse physiological functions of β2GPI, and then relates them to its role in our current understanding of the pathophysiology of APS. The third chapter presents a critical review of the evidence base for the diagnosis and management of APS. The fourth chapter describes the interaction between β2GPI and the glycoprotein Ib alpha (GPIbα) subunit of the platelet receptor GPIb-IX-V. GPIbα is an important platelet adhesion receptor, which mediates multiple additional functions on the platelet surface, including binding coagulation factor XI (FXI). The implication of the interaction between β2GPI and GPIbα on platelet activation and the release of thromboxane in the presence of anti-β2GPI antibodies is explored, as well as the intracellular pathways via which this activation occurs. The relevance of these findings to understanding APS pathogenesis, in particular thrombosis, is discussed. The fifth chapter delineates the interaction between the fifth domain of β2GPI and FXI and its activated form factor XIa (FXIa). The ability of FXIa to cleave β2GPI between lysine (Lys) 317 and threonine (Thr) 318, and modulate its function is reported. The sixth chapter describes the ability of β2GPI to inhibit FXIa autoproteolytic hydrolysis at the specific FXIa residues arginine (Arg) 507, Arg532 and Lys539. This interaction with β2GPI stabilizes FXIa activity over time, and leads to enhanced FXIa mediated fibrin formation. This is a novel physiological function of β2GPI with important implications. Recent epidemiological studies by others have emphasized the critical role of FXIa in pathological thrombus propagation. The seventh chapter defines the relevance of the FXIa residues Arg507, Arg532 and Lys539 to FXIa mediated inactivation by the main FXIa inhibitor Protease Nexin 2 (PN2), and by Antithrombin III (ATIII). Insights into future directions for research are presented and discussed within each individual chapter.

Beta 2 glycoprotein I (β2GPI) is a major antigenic target in antiphospholipid syndrome (APS). In vitro studies suggest that it may have multifaceted physiological functions, as it displays both anticoagulant and procoagulant properties. Beta 2GPI may bind to FXI and serve as a regulator of FXI activation by thrombin. The possible interaction of β2GPI with thrombin is investigated using enzyme linked immunosorbent assays and surface plasmon resonance based studies. It is demonstrated for the first time that domain V of β2GPI is involved in direct binding to thrombin, and exosites I and II on thrombin take part in this interaction. It is also shown that cleavage of β2GPI at Lys317-Thr318 does not interrupt this binding. A quaternary complex is proposed on the surface of activated platelets in which β2GPI may colocalise with FXI and thrombin to regulate FXIa generation. The effect of anti-β2GPI monoclonal antibodies (mAbs) were investigated on this system using 8 anti-β2GPI mAbs directed against domain I. Anti-β2GPI Abs potentiate the suppressing activity of β2GPI on FXI activation by thrombin. Moreover, they restore the inhibitory effect of clipped β2GPI on this system. The current study demonstrates for the first time a novel biological consequence of thrombin interaction with β2GPI. The effect of β2GPI on thrombin inactivation by the serine protease inhibitor heparin cofactor II (HCII) is investigated using chromogenic assays, platelet aggregation studies, and the platelet release response. The current work shows that β2GPI protects thrombin from inactivation by HCII/Heparin. This ability is modulated by the cleavage of β2GPI. A ternary structure is proposed between β2GPI, thrombin and heparin which may limit the N-terminus of HCII to exosite I therefore inhibit thrombin inactivation by HCII. The effect of anti-β2GPI Abs is examined in this system using patient polyclonal IgGs and a murine anti-β2GPI mAb. Anti-β2GPI Abs potentiate the protective effect of β2GPI on thrombin inhibition by HCII/Heparin. In view of the importance of HCII in regulating thrombin activity within the arterial wall, disruption of this function by β2GPI/anti-β2GPI Ab complexes may be particularly relevant in arterial thrombosis in APS. Beta 2 glycoprotein I (β2GPI) is a major antigenic target in antiphospholipid syndrome (APS). In vitro studies suggest that it may have multifaceted physiological functions, as it displays both anticoagulant and procoagulant properties. Beta 2GPI may bind to FXI and serve as a regulator of FXI activation by thrombin. The possible interaction of β2GPI with thrombin is investigated using enzyme linked immunosorbent assays and surface plasmon resonance based studies. It is demonstrated for the first time that domain V of β2GPI is involved in direct binding to thrombin, and exosites I and II on thrombin take part in this interaction. It is also shown that cleavage of β2GPI at Lys317-Thr318 does not interrupt this binding. A quaternary complex is proposed on the surface of activated platelets in which β2GPI may colocalise with FXI and thrombin to regulate FXIa generation. The effect of anti-β2GPI monoclonal antibodies (mAbs) were investigated on this system using 8 anti-β2GPI mAbs directed against domain I. Anti-β2GPI Abs potentiate the suppressing activity of β2GPI on FXI activation by thrombin. Moreover, they restore the inhibitory effect of clipped β2GPI on this system. The current study demonstrates for the first time a novel biological consequence of thrombin interaction with β2GPI. The effect of β2GPI on thrombin inactivation by the serine protease inhibitor heparin cofactor II (HCII) is investigated using chromogenic assays, platelet aggregation studies, and the platelet release response. The current work shows that β2GPI protects thrombin from inactivation by HCII/Heparin. This ability is modulated by the cleavage of β2GPI. A ternary structure is proposed between β2GPI, thrombin and heparin which may limit the N-terminus of HCII to exosite I therefore inhibit thrombin inactivation by HCII. The effect of anti-β2GPI Abs is examined in this system using patient polyclonal IgGs and a murine anti-β2GPI mAb. Anti-β2GPI Abs potentiate the protective effect of β2GPI on thrombin inhibition by HCII/Heparin. In view of the importance of HCII in regulating thrombin activity within the arterial wall, disruption of this function by β2GPI/anti-β2GPI Ab complexes may be particularly relevant in arterial thrombosis in APS.

Thesis (Ph. D.)--University of Missouri--Columbia, 1996. / "December 1996." Typescript. Vita. Includes bibliographical references (leaves [128]-155). Also available on the Internet.

Class of 2012 Abstract / Specific Aims: We sought to determine the influence of genetic variation of ADRB2 on the airway response to albuterol in patients with CF when compared to matched healthy controls at baseline and at 60 minutes following the administration of albuterol (2.5mg diluted in 3ml normal saline). Methods: Baseline pulmonary function (forced vital capacity, FVC, forced expiratory flow in 1-second, FEV1, mid-maximal expiratory flow, MMF, and forced expiratory flow at 50% of the FVC) was assessed in 17 patients with CF and 31 healthy subjects. Main Results: As expected, the healthy group had higher baseline pulmonary function when compared to the CF group (FVC=97±3 vs. 83±5; FEV1=95±3 vs. 72±6; MMF=90±4 vs. 54±8, % predicted for healthy and CF, respectively, mean±SE, p<0.05 for all. We compared Arg16Arg to Arg16Gly/Gly16Gly subjects. There was no effect of genotype on the response to albuterol in healthy subjects. However, in the CF group, we found that the Arg16Arg group (n=6) had an attenuated response to β-agonist when compared to the Gly-containing group (n=11) (FVC=0±0.9 vs. 6±3: FEV1=3±1 vs. 7±4: MMF=12±3 vs. 12±5 % change, for Arg16Arg and Gly-containing groups, respectively, p<0.05 for FVC, p=0.06 for FEV1). Conclusions: These results demonstrate a differential response to β-agonists according to genetic variation of the ADRB2 at amino acid 16. Due to the differences in FVC and FEV1 but not in MMF, these data suggest that the genetic difference in airway function is primarily in bronchodilation of the larger airways.

Memoria para optar al título de Químico Farmacéutico / Los fibroblastos cardiacos son células que cumplen un rol fundamental en el mantenimiento de la homeostasis de la matriz extracelular del corazón. Luego de un daño al miocardio, además, participan activamente del remodelado cardiaco como tal o diferenciándose a miofibroblasto, un fenotipo celular que presenta características que lo hacen apto para funciones de cicatrización. Se ha observado que luego de un daño al miocardio, el corazón está expuesto a un mayor tono adrenérgico con la finalidad de compensar la disfunción adquirida por la injuria del tejido. Estudios de nuestro laboratorio han demostrado que la estimulación β2-adrenérgica por Isoproterenol induce autofagia en fibroblastos cardiacos de rata adulta, un proceso degradativo que se ha reportado capaz de perder su equilibrio en diversas patologías cardiovasculares. Por esto, se vuelve interesante determinar si estos mismos estímulos son capaces de inducir autofagia en miofibroblastos cardiacos, células que aparecen sólo cuando hay daño al miocardio. Los resultados muestran que tanto fibroblastos como miofibroblastos cardiacos presentan receptores adrenérgicos sólo del subtipo β2. Miofibroblastos cardiacos presentaron mayor número de receptores β2-adrenérgicos y con mayor afinidad por sus ligandos que fibroblastos cardiacos. En ambos fenotipos celulares los receptores mencionados se encuentran funcionales. En cuanto a la autofagia, los estímulos clásicos inductores de autofagia (rapamicina y/o privación de nutrientes) y la estimulación β2-adrenérgica por Isoproterenol inducen autofagia en fibroblastos. De modo distinto, estos inductores no fueron capaces de inducir autofagia en miofibroblastos cardiacos de rata adulta, aunque se encontró que en condiciones basales presentaban mayor nivel de autofagia que los fibroblastos. Los resultados demuestran que los miofibroblastos cardiacos son resistentes a la inducción de autofagia por estimulación β2-adrenérgica, lo que puede abrir una puerta para el entendimiento del rol de este proceso en estados patológicos del corazón.

No description available.