Evidence suggests different sections of the arteriolar network supplying muscle can respond independently and this may provide a mechanism for the localized distribution of blood flow. This hypothesis was tested in the microcirculation of the cat sartorius muscle by measurement of arteriolar diameter changes during muscle contraction and sympathetic nerve stimulation in each consecutive section of the network. The diameter changes were referenced to the initial distribution of resistance across the network, as determined from arteriolar pressure measurements and morphometric data. This led to an estimate of the change in network resistance. Unlike previous reports, the most distal arterioles dilated little during muscle contraction and our resistance estimate indicates these vessels play an insignificant role in functional hyperemia. The more proximal, third order arterioles dilated proportionately more than other arteriolar orders and made the largest single contribution to resting resistance. Similarly, these vessels were the largest single site of resistance change during sympathetic stimulation. Together, these findings suggest the third order arterioles play a dominant role in regulating flow to the capillaries that each supplies. Antagonism of sympathetic control during muscle contraction has been attributed to direct inhibition of vascular smooth muscle contraction and to inhibition of sympathetic neurotransmission. Evidence to support the latter mechanism comes from the observation that functional dilation is reduced with exogenous norepinephrine as compared to sympathetic stimulation. However, exogenous norepinephrine may bind to both alpha-1 and alpha-2 adrenergic receptors, whereas that released by sympathetic stimulation may bind primarily to alpha-1 receptors. Since this difference could be significant, functional dilation after systemic injection of norepinephrine or phenylephrine, a selective alpha-1 agonist, was compared to that during sympathetic stimulation. In contrast to the findings with norepinephrine, functional dilation after phenylephrine did not differ from that observed during sympathetic stimulation. This indicates the dilator substance(s) released during exercise may selectively inhibit alpha-1 mediated vasoconstriction but less effectively inhibit vasoconstriction mediated by alpha-2 receptors. Furthermore, these findings suggest that the vasodilator mechanism may act primarily at the level of the vascular smooth muscle, without appreciable pre-junctional inhibition of sympathetic nerves.

published_or_final_version / Medicine / Master / Master of Philosophy

Reflexology is one of the top six complementary therapies used in the UK. Reflexologists claim that massage to specific points of the feet increases blood supply to referred or 'mapped' organs in the body. Empirical evidence to validate this claim is scarce. This three-phase RCT measured changes in haemodynamic parameters in subjects receiving reflexology treatment applied to specific areas of the foot which are thought to correspond to the heart (intervention) compared with reflexology applied to other areas on the foot which are not (control).

Thesis (Ph.D.)--University of Melbourne, Dept. of Medicine, 2002. / Typescript (photocopy). Includes bibliographical references (leaves 308-353).

Thesis (doctoral)--Københavns Universitet. / Summary in Danish.

INTRODUÇÃO: Exercícios físicos são utilizados como terapia nãofarmacológica para o tratamento da hipertensão arterial e o treinamento físico (TF) por natação é reconhecido por produzir remodelamento cardíaco em animais experimentais. Entretanto, a ação vasodilatadora da adenosina (ado) resultante do exercício físico como prevenção e tratamento da hipertensão é pouco explorada. OBJETIVO: Avaliar remodelamento cardíaco e papel da adenosina na distribuição do fluxo sanguíneo para o miocárdio após treinamento físico em SHR. MÉTODO: 28 SHR machos babies e adultos foram submetidos ao TF aeróbio de natação, durante 10 semanas (5x/sem - 1h/dia). Foram utilizados protocolos de microesferas coloridas para avaliar fluxo sanguíneo, técnicas de morfologia para avaliar hipertrofia cardíaca e análises bioquímicas para verificar atividade de enzimas envolvidas na formação de adenosina. RESULTADOS: TF por natação atenuou a evolução da HA em SHR babies (S: 145±2; T: 140±2 mmHg), promoveu bradicardia de repouso em SHR adultos (S: 340±4; T: 321±6 bpm) e desenvolveu HC nos dois grupos (TB: 12%; TA: 10%). Na condição basal, o TF aumentou o FS coronário em SHR babies (S: 4745±2145; T: 6970±2374 mi/coração) e maior resposta vasodilatadora à infusão de adenosina foi observada (S: 18946±6685; T: 25045±7031 mi/coração). Nesse grupo o TF promoveu maior atividade da enzima 5-nucleotidase, levando à maior formação de adenosina (S: 0.45±0.09; T: 1.01±0.05). CONCLUSÃO: O TF de natação, além de desenvolver HC e apresentar maior hidrólise de AMP, promoveu aumento no FS coronário, sendo mostrado que desempenha um importante papel na regulação da hipertensão / ABSTRACT: Exercise training (ET) has been used as non-pharmacological therapy for hypertension treatment and the swimming physical training is recognized for yield cardiac remodeling in experiments. However, little is known on the effects of adenosine (Ado) resulting from ET as hypertension prevention and treatment. OBJECTIVE: To evaluate cardiac remodeling and the role of adenosine in cardiac blood flow distribution (BF) to the myocardium after aerobic ET on SHR. METHODS: 28 male SHR, babies and adults, were submitted to swimming training protocol during 10 weeks (5 times a week 1 h a day). Colored micro spheres protocols were used to evaluate blood flow, morphological techniques were used to evaluate cardiac hypertrophy and biochemical analysis were performed to verify enzyme activity in the adenosine formation. RESULTS: ET attenuated the evolution of hypertension in babies SHR group (S: 145±2; T: 140±2 mmHg), HR was lower in adults SHR (S: 340±4; T: 321±6 bpm) and CH increased in both groups (TB: 12%; TA: 10%). At basal condition, BF was increased in trained babies (S: 4745±2145; T: 6970±2374 mi/heart) and higher vasodilatation response were observed due to adenosine infusion (S: 18946±6685; T: 25045±7031 mi/heart). In this group, the ET promoted a higher 5- nucleotidase enzyme activity leading to a higher adenosine formation (S: 0.45±0.09; T: 1.01±0.05). CONCLUSION: The swimming training developed CH as well as increased adenosine formation, leading to higher coronary blood flow, being demonstrated its important role in hypertension regulation

by Lo Ming Yip. / "July 1998." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (p. 208-247). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstract in Chinese.

The overall goal of this research is to improve the use of seated tilt to increase function, health and quality of life for people using power wheelchairs. Specifically, the objective of this dissertation is to evaluate the biomechanical responses to seated full body tilt and their relationships to the actual use of tilt-in-space wheelchairs. In the first phase of this study, researchers remotely monitored how 45 fulltime power wheelchair users used their tilt-in-space systems. Participants spent an average of 12.1 hours in their wheelchair each day. They spent more than 2 hours seated at positions greater than 15° and performed tilts of 5° or greater every 27 minutes, but rarely performed tilts past 30°. Two distinct types of tilt behavior were identified: uni-modal (staying at a single position more than 80% of the time) and multi-modal (staying at a single position less than 80% of the time). Participants in the multi-modal group tilted significantly more frequently (4 times per hour) than the uni-modal group, and did not have a single typical position. Participants without sensation were more likely to exhibit uni-modal behavior. In the second phase of this study, researchers used interface pressure measurements and laser Doppler flowmetry to study changes in localized loading and superficial blood flow at the ischial tuberosities across different amounts of tilt. Eleven participants with spinal cord injuries were studied in a laboratory setting. Results showed that biomechanical responses to tilt were highly variable. Pressure reduction at the ischial tuberosity was not present at 15°, but did occur with tilts to 30° and greater, and could be explained by the tilt position and upright pressure. Unlike pressure, blood flow increased with all tilts from an upright position, but did not increase when tilting from 15° to 30°. Only 4 of 11 participants had a considerable increase (≥10%) in blood flow at 30° tilt, whereas 9 participants did during maximum tilt (i.e., 45°-60°). Based on the results of this study, tilting for pressure reliefs as far as the seating system permits is recommended to maximize the potential for significant blood flow increases and pressure relief.

Bibliography: leaves 148-166. / xi, 166 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The chicken embryo's ability to match the perfusion of its chorioallantoic membrane to regional differences in shell conductance was investigated. / Thesis (Ph.D.)--Adelaide University, Dept. of Environmental Biology, 2001

Diss. (sammanfattning) Linköping : Linköpings universitet, 2005. / Härtill 4 uppsatser.