Differential blood flow responses to CO2 in human internal and external carotid and vertebral arteries

摘要: Arterial CO2 serves as a mediator of cerebral blood flow(CBF), and its relative influence on the regulation CBF is defined reactivity. Our previous studies have demonstrated that there are differences in responses to physiological stimuli (i.e. dynamic exercise orthostatic stress) between arteries humans. These findings suggest reactivity may be different anterior posterior circulation. The aim this study was identify by measuring flow examine potential internal carotid artery (ICA), external (ECA) vertebral (VA). In 10 healthy young subjects, we evaluated ICA, ECA, VA duplex ultrasonography (Vivid-e, GE Healthcare), mean velocity middle (MCA) basilar (BA) transcranial Doppler (Vivid-7, healthcare) during two levels hypercapnia (3% 6% CO2), normocapnia hypocapnia estimate To characterize cerebrovascular CO2,we used both exponential linear regression analysis estimated partial pressure arterial CO2, calculated end-tidal CO2. significantly lower than ICA (coefficient 0.021 ± 0.008 vs. 0.030 0.008; slope 2.11 0.84 3.18 1.09% mmHg−1: P <0.01). Lower circulation persistent distal intracranial (exponent 0.023 0.006 0.037 0.009; 2.29 0.56 3.31 0.87% BA MCA). contrast, ECA markedly intra-cerebral 0.007; 0.63 0.64% mmHg−1, indicate vertebro-basilar has circulation, diminished compared which explain stress.