Searching for the Vascular Component of the Arterial Baroreflex

Short-term regulation of arterial blood pressure is accomplished by complex interactions between feedback and feed-forward information from the arterial and cardiopulmonary baroreceptors that combine with other local and neural factors to modulate cardiac output (heart rate and stroke volume) and total peripheral vascular resistance. In this paper we used transfer function analysis and autoregressive moving average analysis to explore the interrelationships between central venous pressure as an input to the cardiopulmonary baroreflex and mean arterial blood pressure as an input to the arterial baroreflex in the regulation of total peripheral resistance. We further compared the peripheral vascular responses with those of the cerebrovascular system where the dominant factor regulating cerebral blood flow is accepted to be dynamic autoregulation. The results indicate that the peripheral vascular system responds with a myogenic response and that arterial baroreflex does not play an important role in modulating arterial vascular resistance in supine rest or mild orthostatic stress. The cardiopulmonary baroreflex was important in the regulation of total peripheral resistance. The blood pressure to vascular resistance relationship was qualitatively similar in the peripheral and the cerebrovascular systems pointing to the dominance of vascular autoregulation.