The human ABCG2 (second member of ABC transporter G-subfamily) is an important ATP-dependent exporter in the body with broad substrate specificity including xenobiotics (e.g. anticancer agents) and endogenous compounds (e.g. sterols and lipids). ABCG2 was first discovered in a multidrug resistant breast cancer cell line and it is suggested to cause resistance to chemotherapy in certain cancers such as acute myeloid leukaemia and small cell lung cancer. Physiologically, ABCG2 is found in the protective sanctuary sites of the body, for instance the gut and blood-brain-barrier, affecting pharmacokinetics and treatment efficacies of small molecule drugs. Structurally, the polypeptide chain of ABCG2 contains a single nucleotide binding domain and a single transmembrane domain, which is half the number of domains required for a fully functional ABC transporter. Although many have suggested that ABCG2 function as dimer or higher order oligomer, studies so far have been unable to convincingly address the oligomeric state of ABCG2. We aim to bridge this knowledge gap by resolving the oligomerisation of ABCG2 using fluorescence techniques in mammalian cells. The expression and function of fluorescent proteins tagged ABCG2 were verified using confocal imaging and fluorescence accumulation assays, prior to the fluorescence studies. As the membrane dynamics of ABCG2 are unknown, we first measured the diffusion of ABCG2 in live HEK293T cells using fluorescence recovery after photobleaching (FRAP) microscopy, in comparison to membrane localised fluorescent proteins and a full length (i.e 4 domain) ABC transporter (ABCC4). We also demonstrated oligomerisation of ABCG2 by measuring a specific increase in fluorescence resonance energy transfer (FRET) efficiency between CFP- and YFP-tagged ABCG2 expressed in live HEK293T cells in comparison to non-specific control interactions, including with the adenosine A3 receptor. Subsequently, we employed high resolution and single particle fluorescence techniques to resolve the oligomeric organisation of ABCG2. First, fluorescence fluctuations of tagged ABCG2 within a confocal volume, positioned on the upper plasma membrane, were measured using fluorescence correlation spectroscopy (FCS) at “single molecule” resolution. Photon counting histogram (PCH) analysis of the FCS measurements was performed to determine the molecular brightness of the fluorescent species detected within the confocal volume. Using CD86 and CD28 as monomer and oligomer controls respectively, PCH analysis demonstrated higher order oligomer formation of ABCG2, with increased brightness (up to 4-fold) observed for both ABCG2 and CD28, compared to CD86. For validation of the oligomeric organisation of ABCG2, we acquired a series of single particle photobleaching images of cells expressing fluorescent protein tagged ABCG2 using total internal reflection fluorescence (TIRF) microscopy at the lower plasa membrane, and employed a step detection algorithm to identify the number of photobleaching steps within the distinguished fluorescent spots. Statistical modelling of the photobleaching step frequency histogram provided credible evidence of tetrameric organisation of ABCG2 in the plasma membrane. The findings and methodology presented in this study have provided further insights into the membrane dynamics and oligomerisation of ABCG2. This could lead to future studies to explore new pharmacological avenues that target the oligomerisation interfaces of ABCG2.

Precise and complete replication of the genome is essential for a cell. Chromosome replication follows a defined temporal order, depending on the efficiency and timing of the replication origins. However, the mechanism regulating origin activity has not been properly explained to date. Yeast replication origins are very well characterized and well studied. Genome wide replication in yeast was detailed through deep sequencing in various studies. In yeast, there are multiple replication origins for the complete replication of the genome. In Saccharomyces cerevisiae, there are ~400 replication origins, which are also referred to as Autonomously Replicating Sequences. Replication origins have varied levels of activity and varying times of activation. There are many lines of evidences, which suggest that the origins function differently in mitotic and meiotic cell cycles. It was thought that same origins function both during mitosis and meiosis. However, there is a difference in the replication timings of both the cell cycles, the reason for which is not known. Meiotic cell cycle is longer than the mitotic cell cycle. By using the plasmid-based assays, specific origins were selected and origin activity was analyzed during mitosis and meiosis to see if individual origins show any differences in origin activity. For all the origins tested, the meiotic activity was found to be less than the mitotic activity, which provides a possible explanation for a longer pre-meiotic S phase. Most of the confirmed yeast replication origins are present in the intergenic regions of the chromosome. Due to the presence of majority of replication origins in the intergenic regions and not on the genes, it was thought that the gene transcription might be detrimental to origin activity, hence not supporting the existence of an origin on a gene. Careful analysis of genome wide replication data along with plasmid based ARS assays confirmed that a few replication origins are present within genes. Assays were preformed to study the relation between transcription and origin activity both during mitosis and meiosis. Mitotic origin activity was shown to have no known affect from gene transcription. However, due to some unknown technical faults or other reasons, assays to find out transcription and meiotic activity were not successful.

published_or_final_version / Architecture / Master / Master of Landscape Architecture

Thesis (Ph. D.)--University of Washington, 1992. / Vita. Includes bibliographical references (leaves [294]-310).

Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-01-03T17:52:43Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) elizangela_souza_pereira.pdf: 689237 bytes, checksum: 793cce78db5facc852c0b626695e1359 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-01-31T16:46:41Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) elizangela_souza_pereira.pdf: 689237 bytes, checksum: 793cce78db5facc852c0b626695e1359 (MD5) / Made available in DSpace on 2017-01-31T16:46:41Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) elizangela_souza_pereira.pdf: 689237 bytes, checksum: 793cce78db5facc852c0b626695e1359 (MD5) Previous issue date: 2016 / O eucalipto pertence ao g?nero Eucalyptus spp. (Myrtaceae) possui in?meras esp?cies e variedades, prosperaram em diversos habitats. O controle qu?mico ? o principal m?todo de controle de lepid?pteros desfolhadores que atacam o eucalipto. O controle biol?gico ? uma alternativa para tentar reduzir a utiliza??o de produtos qu?micos nos sistemas florestais. O objetivo desta disserta??o foi avaliar a seletividade do inseticida Decis 25 CE? (deltametrina) ao parasitoide Palmistichus elaeisis Delvare & LaSalle (Hymenoptera: Eulophidae) e estudar os efeitos sobre os par?metros biol?gicos e os efeitos subletais ao longo de tr?s gera??es do parasitoide. O primeiro bioensaio foi realizado em delineamento inteiramente casualizado, com nove tratamentos e dez repeti??es. Os tratamentos foram constitu?dos pelo controle (?gua destilada) e as concentra??es de deltametrina: 0,64 mg i.a./L, 1,4 mg i.a./L, 3,10 mg i.a./L, 6,83 mg i.a./L, 15,03 mg i.a./L, 33,05 mg i.a./L, 72,7 mg i.a./L e 160 mg i.a./L aplicadas sobre o hospedeiro alternativo Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae). A deltametrina reduziu a taxa de parasitismo de P. elaeisis. Nas doses intermedi?rias (6,83 mg i.a./L ? 33,05 mg i.a./L) o parasitismo ficou em torno de 65%, e nas doses mais elevadas (72,7 mg i.a./L e 160 mg i.a./L ) o parasitismo decresceu a 10%. Houve uma redu??o significativa na taxa de emerg?ncia com o aumento da concentra??o do inseticida. N?o foram observadas diferen?as significativas na longevidade parental e da prole de P. elaeisis. O comprimento da c?psula cef?lica e da t?bia posterior apresentou diferen?as significativas. O segundo bioensaio foi realizado com tr?s tratamentos e vinte repeti??es. Os tratamentos foram constitu?dos pelo controle (?gua destilada), pela CL10= 11,12 mg de i.a/L e a CL50= 18, 54 mg de i.a/L. As pupas de T. molitor foram expostas ao inseticida atrav?s do m?todo de imers?o. Sessenta pupas de T. molitor foram mergulhadas por dois segundos em solu??o dilu?da para 100 mL com as concentra??es do inseticida. Na primeira gera??o F1 da CL10 o parasitismo foi de 55% e a CL50 ficou em 30%. Na segunda gera??o a taxa de parasitismo da CL10 foi de 70% e a da CL50 foi de 40%. Na ?ltima gera??o avaliada, n?o houve diferen?as significativas. A taxa de emerg?ncia das tr?s gera??es da CL10 apresentou diferen?as significativas. Entretanto, a emerg?ncia das gera??es F1, F2 e F3 da CL50 foram semelhantes entre si. A longevidade da prole de todas as gera??es avaliadas apresentou diferen?as significativas. A deltametrina afetou todos os par?metros avaliados de P. elaeisis, podendo ser considerado extremamente nocivo, comprovando que este inseticida n?o ? seletivo para esta esp?cie. Ap?s tr?s gera??es o parasitoide ainda ? afetado negativamente. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Produ??o Vegetal, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016. / Eucalyptus belongs to the genus Eucalyptus spp. (Myrtaceae) has many species and varieties thrive in different habitats. Chemical control is the main defoliating lepidopteran control method that attack eucalyptus. Biological control is an alternative to try to reduce the use of chemicals in forest systems. The aim of this work was to evaluate the selectivity of insecticide Decis 25 CE? (deltamethrin) to the parasitoid Palmistichus elaeisis Delvare & LaSalle (Hymenoptera: Eulophidae) and study the effects on biological parameters and sublethal effects over three generations of the parasitoid. The first bioassay was conducted in a completely randomized design with nine treatments and ten repetitions. The treatments were the control (distilled water) and the concentrations of deltamethrin: 0.64 mg ai / L, 1.4 mg ai / L, 3.10 mg ai / L, 6.83 mg ai / L, 15, 03 mg ai / L, 33.05 mg ai / L, 72.7 mg ai / L and 160 mg ai / L applied on the alternate host Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae). The deltamethrin reduced the rate of parasitism of P. elaeisis. In the intermediate doses (6.83 mg ai / L - 33.05 mg ai / L) parasitism was around 65%, and in higher doses (72.7 mg ai / L and 160 mg ai / L) parasitism decreased to 10%. There was a significant reduction in germination rate with increasing concentrations of the insecticide. No significant differences were observed in parental longevity and P. elaeisis offspring. The length of the head capsule and the posterior tibia showed significant differences. The second bioassay was conducted with three treatments and twenty repetitions. The treatments were the control (distilled water), the CL10 = 11.12 mg of a.i. / L and LC50 = 18, 54 mg of a.i. / L. The pupae of T. molitor were exposed to the insecticide through the immersion method. Sixty pupae of T. molitor were dipped for two seconds in dilute to 100 ml with the insecticide concentrations. In the first generation F1 CL10 parasitism was 55% and the LC50 was 30%. In the second generation CL10 parasitism rate was 70% and LC50 was 40%. In the last generation evaluated, no significant differences. The emergence rate of three generations of the CL10 showed significant differences. However, the emergence of F1, F2 and F3 CL50 were similar. The longevity of the offspring of all generations evaluated showed significant differences. The deltamethrin affected all parameters of P. elaeisis and can be considered extremely harmful, proving that this insecticide is not selective for this species. After three generations the parasitoid is still negatively affected.

Introduction: The P2Y14 receptor, with its unique pharmacologic profile, is the only member of its P2Y family that is activated by UDP-sugar nucleotides as well as MRS2690, the synthetic analogue of UDP-glucose. Its role in the immune and inflammatory systems is well documented; however its role in the cardiovascular system and, particularly, the vasculature is beginning to emerge. Aims and Objectives: The aim was to provide evidence for the expression and the role of the P2Y¬14 receptor in porcine coronary arteries. The objectives of the study were to characterize the P2Y14 receptor response profile in the presence of a P2Y14 receptor antagonist, PPTN, in the porcine coronary artery using organ bath pharmacology. The effects of non-selective P2 receptor antagonists, suramin and PPADS and the P2Y¬6 receptor antagonist MRS2578, on responses to UDP-glucose and MRS2690 were investigated. P2Y14 receptor protein expression and receptor localization was explored using Western blot and immunohistochemistry. P2Y14 receptor coupling to the inhibition of adenylyl cyclase/cAMP activity, using a vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) bead assay, in porcine coronary arteries was determined. Human isolated red blood cells (RBCs) and platelets as sources of UDP-glucose were investigated. Hypoxia-induced release of UDP-glucose from porcine coronary arteries was also investigated. The function of the P2Y14 receptor as an anti/pro-inflammatory stimulus in porcine coronary arteries was also explored. Results: UDP-glucose, UDP-N-acetylglucosamine and UDP-glucuronic acid elicited concentration-dependent contractions in the porcine coronary artery; MRS2690-induced contractions were 10-fold more potent than those of the UDP-sugars. The contractile responses to MRS2690, but not UDP-glucose, were significantly inhibited by PPTN (3 µM) (in presence of U46619 and forskolin to precontract and raise cAMP, respectively). The contractile responses to UDP-glucose, but not MRS2690, were altered (either inhibited or potentiated) in the presence of suramin and PPADS. MRS2578, a P2Y6 receptor antagonist, did not change the contractile responses to UDP-glucose or MRS2690 in U46619 preconstricted coronary arteries. MRS2578 did not change the contractile responses to MRS2690, but did to UDP-glucose (in the presence of forskolin plus U46619). Immunoblotting showed that the P2Y14 receptor protein exists in two isoforms, sized 41 kDa and 61 kDa in porcine coronary arteries. Immunohistochemistry revealed localization of P2Y14 receptors in the vascular smooth muscle cells and endothelium of porcine coronary arteries. UDP-glucose and MRS2690 significantly decreased VASP-P in coronary arteries, an effect which was partially reversed in the presence of PPTN. Red blood cells induced contractions in preconstricted porcine coronary arteries; the response remained unchanged in the presence of PPTN. Platelets induced relaxations and contractions in the absence and presence of L-NAME (inhibitor of nitric oxide synthase), respectively, in porcine coronary arteries; the response remained unchanged in the presence of PPTN. PPTN does not change hypoxia induced relaxation in preconstricted coronary arteries. UDP-glucose and MRS2690 had no significant effect on the release of cytokines/chemokines from segments of coronary arteries. Conclusion: The action of UDP-sugars and MRS2690, P2Y14 receptor agonists, as inducers of contraction is consistent with an involvement of functional P2Y¬14 receptors in porcine coronary arteries. Inhibition by PPTN, a selective P2Y14 receptor antagonist, of contractile responses to a selective P2Y14 receptor agonist, MRS2690, further provides evidence of P2Y14 receptors in porcine coronary arteries. Release of purine and pyrimidine nucleotides is known to be exaggerated in pathophysiological conditions, such as shear stress, endothelial cell damage and hypoxia. This may elicit chronic activation of P2 receptors including P2Y14 receptors, consequently causing increased vasoconstriction of porcine coronary arteries. The patho/physiological sources and stimuli for local UDP/UDP-glucose release remain to be determined since PPTN did not block responses to RBCs, platelets and hypoxia under the conditions of the present study. The P2Y14 receptor may be a novel target to control abnormal vascular contraction under pathophysiological conditions.

Made available in DSpace on 2016-08-29T14:11:24Z (GMT). No. of bitstreams: 1 tese_4915_.pdf: 1352726 bytes, checksum: f96481b0824f1706fd681509b52fb566 (MD5) Previous issue date: 2011-06-16 / O presente trabalho tem por objetivo principal a análise da obra O templo e a forca, escrita por Luiz Guilherme Santos Neves, em que o episódio histórico da rebelião de escravos acontecida no distrito de Queimado, em 1849, serve de inspiração ao romance. Pretendemos observar a relação entre a história e a ficção na obra, destacando o modo como o texto literário propõe uma revisão do texto histórico, dele se apropriando para completá-lo ou transfigurá-lo, fazendo surgir novas significações para o acontecimento da revolta dos escravos. Para tanto, recorremos a reflexões de alguns pensadores e teóricos da literatura, no sentido de ressaltar as peculiaridades inerentes aos discursos histórico e ficcional. Como base teórica para a análise, adotamos, principalmente, os conceitos de metaficção historiográfica de Linda Hutcheon e dialogismo, elaborado por Mikhail Bakhtin.

Made available in DSpace on 2018-08-24T22:53:16Z (GMT). No. of bitstreams: 1 tese_5204_.pdf: 6948895 bytes, checksum: e794f4a23b657f36750e1fc26070e2eb (MD5) Previous issue date: 2011-08-10 / O uso inadequado de agrotóxicos pode levar à contaminação do ar, solo, mananciais superficiais e subterrâneos, gerando efeitos negativos em organismos terrestres, aquáticos e à saúde humana. O presente trabalho teve como principal objetivo avaliar os mananciais subterrâneos e superficiais da Bacia do Córrego Sossego (Itarana ES), considerando seus usos para abastecimento doméstico e para irrigação, quanto à potencial contaminação por agrotóxicos. Assim, avaliou parâmetros físico-químicos e microbiológicos de qualidade da água. Também foi realizada uma avaliação do risco potencial de contaminação da água por lixiviação dos princípios ativos de agrotóxicos aplicados na bacia, utilizando modelos matemáticos screening, a saber, índice de GUS e método de GOSS. Esse resultado priorizou 05 princípios ativos com alto potencial para lixiviação e o monitoramento das águas dos mananciais superficiais e subterrâneos quanto à presença de resíduos. A coleta das amostras de água foi realizada mensalmente, no período entre maio e dezembro de 2010, em 4 pontos ao longo do córrego Sossego e em 3 poços rasos para coleta de água subterrânea. Embora a região estudada apresentasse um elevado potencial à contaminação por agrotóxicos, os princípios ativos não foram encontrados durante o período de monitoramento, nas amostras de água analisadas. Algumas amostras de água superficial apresentaram desconformidade em relação à legislação CONAMA 357/2005 para rios de classe 2 referentes à contaminação por coliformes termotolerantes (E. coli), oxigênio dissolvido (OD), demanda bioquímica de oxigênio (DBO5) e cor, comprometendo o uso na irrigação de hortaliças e plantas frutíferas. As águas subterrâneas apresentaram indicadores de más condições sanitárias, visto que foram detectadas presenças de E.coli e nitrato em valores superiores aos determinados pelos padrões de potabilidade, comprometendo o uso para abastecimento.

Ubiquitination is a post-translational modification of protein by ubiquitin (Ub) and plays a vital role in the regulation of a number of cellular functions, including protein degradation via the ubiquitin proteasome system (UPS). These functions require recognition of specific ubiquitinated substrates by ubiquitin binding proteins (also known as ubiquitin receptors), which possess ubiquitin binding domains (UBDs) that interact directly with monoubiquitin and/or polyubiquitin chains. There are at least 16 different UBDs to date of which the ubiquitin associated domain (UBA) is an example. Unanchored polyubiquitin chains are a relatively new phenomenon. Studies suggest that these may be involved in the regulation of innate immunity, stress response and aggresome formation and disassembly. The level of unanchored polyubiquitin chains may be controlled by the action of specific ubiquitin ligases that synthesise them, e.g. E2-25K, or deubiquitinating enzymes that release unanchored polyubiquitin chains from polyubiquitinated substrate proteins, e.g. Isopeptidase T (IsoT). Major neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases are characterized by selective neurodegeneration and the formation of protein inclusions containing misfolded and aberrant proteins, and ubiquitin. UPS impairment has been implicated in the cause or progression of neurodegenerative disease. This thesis investigates the interaction of five different UBDs to synthetic ubiquitin; UBA of p62 and ubiqulin1 (UQ1), coupling of ubiquitin conjugation to endoplasmic reticulum degradation (CUE) of Vsp9, ubiquitin binding to ABIN and NEMO (UBAN) of NEMO and zinc finger domain (ZnFUBP) of IsoT. These studies are followed by investigating a mouse model of neurodegeneration caused by conditional genetic 26S proteasomal deletion in mouse forebrain neurons that shows accumulation of ubiquitin. I show in this thesis that the UBDs have different ubiquitin-binding properties. The p62 UBA and Vps9 CUE domains have similar binding affinity to ubiquitin; binding Lys48- and Lys63-linked, and linear polyubiquitin chains, but not to monoubiquitin. The UBAN domain of NEMO binds only to linear polyubiquitin chains. The IsoT ZnFUBP domain, which interacts with the C-terminus of proximal ubiquitin, only binds to unanchored/free ubiquitin. UQ1 did not show differential binding and bound to all species of ubiquitin investigated. Given the limited studies investigating linear and free chains in vivo, I used the UBAN domain of NEMO and the ZnFUBP domain of IsoT to investigate the abundance of linear and unanchored polyubiquitin chains respectively in the mouse brain cortex of control and 26S proteasome-deleted mice. Although I did not detect the presence of linear polyubiquitin in my studies, I demonstrate accumulation of unanchored polyubiquitin chains in the cortex and cortical mitochondria of 26S proteasome-depleted mice. I suggest that the accumulation of unanchored polyubiquitin chains in this mouse model may be due to increased de novo synthesis, disassembly of polyubiquitin chains from polyubiquitinated proteins by the action of deubiquitinating enzymes or inhibition of their degradation by the 26S proteasome. Further investigations of IsoT/USP5 and E2-25 levels did not show any significant differences that may explain the accumulation of unanchored polyubiquitin chains following 26S proteasome impairment. However, I show significantly decreased levels of p-TAK1 in the 26S proteasome-depleted mice compared to controls that will be further investigated in the future.

Clinical trials have established the efficacy and safety of the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) in lowering cardiovascular morbidity and mortality in patients with and without coronary artery diseases. Traditionally, the beneficial effects of statins have been ascribed entirely to their ability to lower serum cholesterol. However, evidence indicates that statins may exert cholesterol-independent or pleiotropic effects. As well as reducing plasma cholesterol levels, statins induce acute vasorelaxation which may contribute to the overall benefits of statins in the treatment of cardiovascular disease. The mechanism underlying this relaxation is unknown. Statins have been shown to alter mitochondrial function. Therefore, the aim of this study was to determine the role of the mitochondria in the relaxation to statins. Changes in rhodamine 123 fluorescence showed that simvastatin, but not pravastatin, depolarized the membrane potential of mitochondria in both isolated smooth muscle cells and intact blood vessels. As simvastatin, but not pravastatin, causes relaxation of the porcine coronary artery, this could be due to this effect on mitochondria. Mitochondria are known as the energy generating centre of the cells. However, there is growing consensus that mitochondria actively participate in intracellular signalling, such as production of reactive oxygen species (ROS) and regulation of the intracellular Ca2+ concentration. Moreover, ROS could play an important supportive role in a variety of vascular cell signalling processes, including activation of nitric oxide synthase (NOS), modulation of intracellular Ca2+, and AMP kinase activation. Therefore, this study investigated whether the relaxation to the lipophilic statin simvastatin is due to an effect on the mitochondria. Relaxation of porcine coronary artery segments by statins was measured using isolated tissue baths. Simvastatin, but not pravastatin, produced a slow relaxation of the coronary artery, which was independent of K+ channel activation, nitric oxide, cyclo-oxygenase, or the endothelium. The relaxation was attenuated by the mitochondrial complex I inhibitor rotenone and the complex III inhibitor myxothiazol, or a combination of the two. Simvastatin inhibited calcium-induced contractile responses, and this inhibition was partially reversed by incubation with the complex I inhibitor rotenone suggesting that mitochondrial function is required for the effect of simvastatin on calcium influx. The effect of mitochondrial complex III inhibitor, antimycin A, was examined as a comparison with simvastatin. Antimycin A induced porcine coronary relaxation and inhibited Ca2+ influx in isolated porcine coronary smooth muscle cells. Evidence from a number of clinical trials highlights a potential association between treatment with lipophilic statins and increased risk of development of diabetes. The close connection between energy metabolism and insulin secretion in pancreatic β-cells suggests that the glycaemic effects of simvastatin may also result from a direct mitochondrial action with reduction in insulin secretion and, hence, result in a reduced control of plasma glucose levels. Although simvastatin depolarized mitochondria in pancreatic β-cells, it also directly inhibited KATP channels. Pravastatin, on the other hand, had no effect on either measurement, suggesting that these phenomena relate to the lipophilicity of the compounds. The inhibition of KATP channels by simvastatin is likely to underlie the increase in insulin secretion observed within days of simvastatin treatment. On the other hand, the effects on mitochondrial membrane potential may be detrimental, particularly with chronic treatment, although further studies are required in order to determine whether this plays a role in the increased risk of diabetes observed with lipophilic statins. Overall, our results demonstrated that simvastatin alters mitochondrial membrane potential in vascular smooth muscle cells and pancreatic β-cells. The relaxation to simvastatin in the porcine coronary artery is dependent, in part, upon mitochondrial activity. Alteration of mitochondrial membrane potential by simvastatin may lead to inhibition of calcium influx, hence stimulation of relaxation. On the other hand, the effects on mitochondrial membrane potential in pancreatic β-cell may be detrimental, particularly with chronic treatment due to the increased risk of diabetes observed with lipophilic statins.