Effect of local heating and vasodilation on the cutaneous venoarteriolar response

Abstract

The cutaneous venoarteriolar response (CVAR) is a local non-adrenergic vasoconstrictor reflex that is engaged via increases in local transmural pressure. The purpose of this study was to determine if local temperature alters the vasoconstrictor ability of the CVAR. Twelve (5 male, 7 female) subjects performed a CVAR maneuver at local temperatures of 30+/-1, 34, 38, and 42 degrees C. CVAR was also engaged after vasodilation via intradermal perfusion of sodium nitroprusside or the attenuation of local heating-induced vasodilation via intradermal perfusion of N(G)-nitro-L: -arginine methyl ester (L: -NAME) in five subjects (2 male, 3 female). CVAR was elicited by rapid cuff inflation to 45mmHg proximal to two dorsal forearm sites for 2 min in both protocols. Local heating caused a progressive increase in skin blood flow (8+/-1, 18+/-4, 43+/-11, and 78+/-2% maximal skin blood flow for 30+/-1, 34, 38, and 42 degrees C, respectively). Engagement of the CVAR decreased skin blood flow by 53+/-2, 57+/-3, and 51+/-4%, for 30+/-1, 34, and 38 degrees C, respectively. In contrast, local heating to 42 degrees C significantly attenuated the CVAR (16+/-11 %). Local administration of sodium nitroprusside during neutral temperature and L: -NAME during local heating also significantly attenuated the vasoconstrictor response of the CVAR by 27+/-8 and 38+/-4%, respectively. These data indicate that CVAR is attenuated at high (42 degrees C) local skin temperatures and that this attenuation is likely due to an effect of both local heating-induced vasodilation and a direct temperature effect.

Combining laser-doppler flowmetry and photoplethysmography to explore in vivo vascular physiology

“…O sistema nervoso simpático também parece ter influência no RVA, em particular na posição between phases I and II (6.8%, p=0.005) in the foot dorsum. This is probably explained by the thermally-induced vasodilation caused by the measurement probe, probably overlapping the VAR-induced vasoconstriction detected ahead [20] . Recent studies indicate that VAR only affects the region adjacent to where the venous pressure has changed [16] .…”

“…Apesar desta redução de perfusão dos dedos dos pés verificou-se um aumento significativo na tcpO 2 medido no dorso do pé entre as fases I e II (6.8%, p=0.005). Este efeito é provavelmente explicado pela vasodilatação induzida pela sonda de medição, sobrepondo-se provavelmente à vasoconstrição induzida pelo RVA detetada adiante [20] . Estudos recentes indicam que o RVA apenas afeta a região adjacente à zona onde a pressão venosa se altera [16] .…”

The effect of Turkish bath on QT dispersion

“…However, there are only a few studies about the acute effects of thermal spring baths. Regarding the acute effects, it is known that hot bath water has a vasodilator effect on vessel system (15). Decrease in the peripheral resistance leads to a meaningful decrease in diastolic pressure.…”

Heat stress and orthostatic tolerance

“…The enhanced cutaneous vasoconstrictor response in the legs, during HUT at the lower angles (15°-45°), was diminished by whole-body heat stress 76) . It is thought that the diminished vasoconstriction was partly caused by modulation of the local vascular response during heat stress, because both whole-body heating and local heating significantly attenuated cutaneous venoarteriolar responses in the forearm 83,84) and the calf 76) . The heat stress-induced reduction of the cutaneous vasoconstrictor response in the lower body, during orthostatic stress, acts to decrease the total PVR and increase blood pooling.…”