Effect Of Isometric Handgrip Exercise On Hypercapnia-induced Shear-mediated Dilation In The Internal Carotid Artery

Abstract

The previous study reported that flow-mediated dilation in peripheral conduit arteries decreased following an acute bout of isometric exercise. On the other hand, it remains unknown whether an acute isometric exercise affects cerebrovascular endothelial function. PURPOSE: The purpose of the present study was to examine the effect of acute isometric handgrip (IHG) exercise on hypercapnia-induced shear-mediated dilation in the internal carotid artery (ICA). METHODS: Four subjects participated in the present study and performed four 2-min IHG exercises at 25% of maximum voluntary contraction. Shear-mediated dilation in the ICA as an index of cerebrovascular endothelial function was measured by using Doppler ultrasound before and immediately after the IHG exercise protocol. Shear-mediated dilation in the ICA was induced by hypercapnia (target end-tidal carbon dioxide; +10mmHg from individual baseline value) and was calculated as the percent rise in peak diameter from baseline value. RESULTS: ICA blood velocity and diameter did not change after acute IHG exercise protocol compared with resting value. Also, shear-mediated dilation in the ICA was unchanged by IHG exercise protocol (4.4±2.0 vs. resting value, 4.5±1.9, P=0.84). CONCLUSIONS: In the present study, the IHG exercise trials did not change cerebrovascular endothelium function. These findings suggest that the response of cerebral endothelial function to IHG exercise is different from that of the peripheral endothelial function.