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Arterial Tone (arterial + tone)
Selected AbstractsEffect Of Anti-Oxidant Treatment And Cholesterol Lowering On Resting Arterial Tone, Metabolic Vasodilation And Endothelial Function In The Human Forearm: A Randomized, Placebo-Controlled StudyCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2001Stephen J Duffy SUMMARY 1. The aim of the present study was to determine whether anti-oxidant therapy with vitamin E and/or cholesterol-lowering therapy with simvastatin would augment resting forearm blood flow (FBF) and metabolic vasodilation in response to exercise and improve endothelial function in young patients with hypercholesterolaemia. 2. Endothelium-dependent and -independent, nitric oxide (NO)-mediated vasodilation have been shown to be impaired in young, otherwise healthy subjects with hypercholesterolaemia. Recent experimental and clinical studies suggest that vascular function may be improved with anti-oxidant or cholesterol- lowering therapy, although these treatments may be synergistic. 3. We compared FBF at rest, in response to isotonic exercise, the endothelium-dependent vasodilator acetylcholine (ACh), the endothelium-independent vasodilator sodium nitroprusside (SNP) and the NO synthase inhibitor NG -monomethyl- L -arginine (L -NMMA) in 26 young, otherwise healthy volunteers (mean (±SD) age 29±7 years; 14 female, 12 male) with hypercholesterolaemia, before and after 6 months treatment with vitamin E, simvastatin and/or placebo. Treatment was randomized, double-blinded in a 2 × 2 factorial design. Forearm blood flow was measured using venous occlusion plethysmography. 4. Vitamin E therapy increased plasma ,-tocopherol from 39.5±9.6 to 75.7±33.8 ,mol/L (P < 0.001). Simvastatin reduced total cholesterol from 6.9±1.7 to 4.9±0.8 mmol/L and low- density lipoprotein (LDL) from 4.8±1.7 to 3.0±0.7 mmol/L (both P < 0.001), although total and LDL,cholesterol also decreased slightly in the placebo group. Vitamin E increased resting FBF from 2.1±0.3 to 2.4±0.3 mL/100 mL per min (P = 0.04) and decreased resting forearm vascular resistance from 42.1±4.2 to 36.1±3.4 units (P = 0.01), but the reduction in resting FBF with L -NMMA was not affected. Vasodilation in response to isotonic exercise, ACh and SNP was similar before and after treatment in the placebo, vitamin E, simvastatin and in the combined vitamin E,simvastatin groups. NG -Monomethyl- L -arginine infusion reduced resting FBF and functional hyperaemia in response to exercise and these responses were not altered by treatment. 5. These data suggest that while vitamin E therapy augments resting FBF and reduces forearm vascular resistance in young hypercholesterolaemic subjects, these effects may not be via NO-dependent pathways. Metabolic vasodilation and responses to the NO-mediated vasodilators ACh and SNP were not favourably affected by anti-oxidant or cholesterol-lowering therapy, either alone or in combination. [source] Differential effects of sevoflurane and propofol anesthesia on left ventricular,arterial coupling in dogsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2010Y. L. J. M. DERYCK Background: General anesthetics interfere with arterial and ventricular mechanical properties, often altering left ventricular,arterial (LVA) coupling. We hypothesized that sevoflurane and propofol alter LVA coupling by different effects on arterial and ventricular properties. Methods: Experiments were conducted in six anesthetized open-chest dogs for the measurement of left ventricular pressure and aortic pressure and flow. Measurements were performed during anesthesia with 0.5, 1.0 and 1.5 minimum alveolar concentration sevoflurane and 12, 24 and 36 mg/kg/h propofol. LVA coupling was assessed as the ratio of ventricular end-systolic elastance (Ees, measuring ventricular contractility) to effective arterial elastance (Ea, measuring ventricular afterload). The steady component of afterload, arterial tone, was assessed by systemic vascular resistance and arterial pressure,flow curves. The pulsatile component of afterload was assessed by aortic impedance and compliance. Results: Sevoflurane decreased aortic pressure and cardiac output more than propofol. Sevoflurane reduced arterial tone, increased arterial stiffness and did not affect wave reflections. It increased Ea, decreased Ees and reduced LVA coupling. Propofol reduced arterial tone, did not affect arterial stiffness and decreased wave reflections. It did not affect Ea, Ees or LVA coupling. Conclusions: Sevoflurane increased ventricular afterload and decreased ventricular performance, thereby altering LVA coupling. Propofol did not affect ventricular afterload or ventricular performance, thereby preserving LVA coupling. Thus, propofol preserves LVA coupling in dogs better, and might be a better choice for patients with compromised left ventricular function. [source] Effects of task difficulty and invested mental effort on peripheral vasoconstrictionPSYCHOPHYSIOLOGY, Issue 5 2004Cristina Iani Abstract We ran two experiments to investigate whether peripheral arterial tone reflects changes in mental effort. Finger pulse wave amplitude, interpulse interval, and pulse variability in the mid- and high-frequency bands were recorded by means of a newly developed finger plethysmograph during both rest and cognitive performance. Using a modified version of the Sternberg memory task, we selectively manipulated either the difficulty of the task (Experiment 1) or the subjects' level of engagement in the task (Experiment 2). We found a significant difference in finger pulse wave amplitude between rest and task periods, suggesting that the measure reflects changes in sympathetic activity due to task engagement. In addition, our results suggest that reduced pulse wave amplitude, signaling vasoconstriction, occurs when subjects are investing effort. [source] Mechanisms of 17 ,-oestradiol induced vasodilatation in isolated pressurized rat small arteriesBRITISH JOURNAL OF PHARMACOLOGY, Issue 3 2000Linda Shaw The influence of 17 ,-oestradiol on pressurized isolated rat mesenteric and coronary small arteries was investigated. 17 ,-oestradiol caused rapid (t1.0<5 mins) concentration-dependent relaxations of pre-contracted pressurized (50 mmHg) isolated rat mesenteric and coronary arteries. Similar responses were observed in both vessel types. Significant relaxations were only observed at concentrations exceeding 3 ,M. The vasodilatory responses in both types of artery were unaffected by 10 ,ML -nitro arginine (L -NNA) alone or in the presence of 10 ,M indomethacin, inhibitors of nitric oxide and prostaglandin synthesis respectively. They were also unaffected by the pre-contracting agent used i.e. high K+ or U46619 (a thromboxane analogue). Neither the oestrogen receptor antagonist ICI 182,780 (10 ,M) nor the protein synthesis inhibitor cycloheximide (100 ,M) had any effect on the responses of mesenteric arteries to 17 ,-oestradiol. 17 ,-oestradiol had only a minor effect on mesenteric arterial diameter over a concentration range similar to the effective vasodilatory range for 17 ,-oestradiol. Membrane impermeant 17 ,-oestradiol conjugated to bovine serum albumin (,-oestradiol-17hemisuccinate-BSA) (E-H-BSA) resulted in a vasodilatation of pressurized arteries. Wortmannin, an inhibitor of myosin light chain kinase, near maximally relaxed pressurized mesenteric arteries although the time course for the response was significantly slower than that for 17 ,-oestradiol. These results taken together suggest that the acute effects of 17 ,-oestradiol on isolated pressurized arterial tone may be due to effects directly on the vascular smooth muscle via non-genomic mechanisms that involve a stereospecific interaction at the plasma membrane. British Journal of Pharmacology (2000) 129, 555,565; doi:10.1038/sj.bjp.0703084 [source] Propofol differently alters vascular reactivity in normotensive and hypertensive ratsCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2002Emmanuel Samain Summary 1.,The effect of propofol on arterial tone in hypertension is poorly understood. We examined the effect of increasing concentrations of propofol (5.6 × 10,8 to 2.8 × 10,3 mol/L) on isometric tension developed by noradrenaline (10,7 mol/L)-contracted aortic rings from 12-week-old Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR). 2.,In both WKY rats and SHR, propofol induced a dose-dependent inhibition of contraction induced by noradrenaline, but the amplitude of relaxation was larger in the SHR than in WKY rats. 3.,The effects of propofol was endothelium independent in WKY rats, whereas in SHR relaxation induced by propofol was greater in endothelium-intact than in endothelium-denuded rings. 4.,In conclusion, we found significant differences in the effect of propofol in hypertensive rats, which may be related to differences in structural and functional properties of the arterial wall observed in hypertension. [source] Hyperoxia-induced arterial compliance decrease in healthy manCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 1 2005Pascal Rossi Summary Introduction:, Oxygen therapy is commonly used in emergency department and intensive care units without careful evaluation of its effects, especially on the haemodynamics and artery characteristics. Materials and methods:, A prospective laboratory study evaluated brachial circulatory effects of normobaric hyperoxia using ultrasonography-Doppler. The study was set in a hospital research laboratory. The subjects were thirteen healthy volunteers. Investigations were performed under normal air ventilation and after 20 min of hyperoxic mixture ventilation using a high concentration mask. Two dimensional images and brachial blood flow velocities were recorded using ultrasonography and pulsed Doppler to study changes in cross sectional area, blood flow, resistance index, and cross-sectional compliance coefficient. Results:, During hyperoxic exposure, mean PaO2 was 372 ± 21 mmHg. A significant decrease of heart rate was observed. Arterial pressures (systolic and diastolic arterial pressures) were not modified. A decrease of cross sectional areas at end diastole and end systole was observed. Pulsed Doppler study showed a decrease of brachial artery blood flow and an increase of the resistance index. Furthermore, a decrease of the cross-sectional compliance coefficient was observed during hyperoxic exposure in all subjects. Conclusion:, This study using two-dimensional ultrasonography and pulsed Doppler could demonstrate an increase in brachial arterial tone and a decrease in brachial blood flow under normobaric hyperoxia. [source] | ||||||||||