Dynamic cerebral autoregulation is unrelated to decrease in external carotid artery blood flow during acute hypotension in healthy young men

作者：Ogoh Shigehiko^*; Sorensen Henrik; Hirasawa Ai; Sasaki Hiroyuki; Washio Takuro; Hashimoto Takeshi; Bailey Damian M; Secher Niels H

来源：Experimental Physiology, 2016, 101(8): 1040-1049.

DOI：10.1113/EP085772

External carotid artery (ECA) vasoconstriction may defend internal carotid artery (ICA) blood flow during acute hypotension. We hypothesized that the (1)-receptor blockade-induced delay in ICA recovery to the baseline level from acute hypoperfusion is related to attenuated ECA vasoconstriction. The ICA and ECA blood flow were determined by duplex ultrasound during thigh-cuff release-induced acute hypotension while the (1)-receptor blocker prazosin [1mg(20kg)(-1)] was administered to nine seated young healthy men. Both ICA (mean +/- SD; by 17 +/- 8%, P=0.005) and ECA (by 37 +/- 15%, P<0.001) blood flow decreased immediately after occluded thigh-cuff release, with a more rapid ICA blood flow recovery to the baseline level (9 +/- 5s) than for the ECA blood flow (17 +/- 5s; P=0.019). The ICA blood flow recovery from hypoperfusion was delayed with prazosin (17 +/- 4s versus control 9 +/- 5s, P=0.006), whereas ECA recovery remained unchanged (P=0.313) despite a similar reduction in mean arterial pressure (-20 +/- 4mmHg versus control -23 +/- 7mmHg, P=0.148). These findings suggest that (1)-receptor blockade-induced attenuation of the ICA blood flow response to acute hypotension is unrelated to the reduction in ECA blood flow. The sympathetic nervous system via the ECA vascular bed does not contribute to dynamic CA during acute hypotension.

• 出版日期2016-8-1