Internal carotid and brachial artery shear-dependent vasodilator function in young healthy humans.

This study compared internal carotid artery (ICA) and brachial artery (BA) endothelium-dependent and -independent vasodilation. We hypothesized that endothelium-dependent and -independent vasodilation of the ICA and BA would be neither similar in magnitude nor correlated between vessels. In 19 healthy adults (23±6 years, 24±3 kg/m2 , 6 female), endothelium-dependent dilation in the ICA was determined via Duplex ultrasound during transiently elevated shear stress caused by increased partial pressure of end-tidal carbon dioxide using dynamic end-tidal forcing (+9mmHg; cerebral flow-mediated dilation, cFMD). BA endothelium-dependent dilation was assessed via standard flow-mediated dilation (FMD). Endothelium-independent dilation in the ICA and BA was assessed concurrently for 10-minutes following administration of 400 μg sublingual glyceryl trinitrate (GTN). Endothelium-dependent vasodilation of the ICA (3.4±2.4%) was lower than (P = 0.013) and not correlated to that of the BA (7.9±3.3%; r2  = 0.00, P = 0.93). Including baseline diameter and shear-rate area under the curve as covariates maintained the difference between cFMD and FMD (3.3±4.2 % vs. 7.8±3.8 %, P = 0.03), while including baseline diameter and baseline shear rate-adjusted area under the curve as covariates abolished it (5.9±3.7 % vs. 5.9.8±3.5 %, P = 0.99). GTN-mediated vasodilation of the ICA (14.3±2.9%) was lower than (P = 0.002) and not correlated to that of the BA (25.5±8.8%; r2  = 0.12...

Source: The Journal of Physiology - September 8, 2020 Category: Physiology Authors: Carr JMJR, Hoiland RL, Caldwell HG, Coombs GB, Howe CA, Tremblay JC, Green DJ, Ainslie PN Tags: J Physiol Source Type: research