血圧制御 「２つの意味と２つの方法」

抄録

It is well established that blood pressure (BP) is controlled by feedback mechanisms, e.g. via baroreceptor reflex. The feedback mechanism supports blood pressure homeostasis to save life at sudden orthostasis or massive hemorrhage. We have shown that sinoaortic denervation abolished BP resetting to a higher level at daily physical activity. This indicates that the baroafferent signal supports active resetting of BP during exercise, suggesting that BP should be controlled not only homeostatically by feedback but also homeodynamically by feedforward mechanisms. The above mechanisms are involved in the short-term control of BP. Resting level of BP is thought to be relatively constant for life-long in health subjects. Lesion of the area postrema, which is a site for neurohumoral interaction with vasopressin and angiotensin II, did not show any abnormality in day-to-day control of BP. In animal-models with salt-sensitive hypertension, vascular endothelial functions or renal functions are impaired but central sympathetic control is preserved, although the central nNOS systems are upregulated to inhibit sympathetic activation. These data lead to the possibility that main causes for abnormality in long-term control of BP might be present in the effector organs but not in the central control system, rather that the central sympathetic system functions to compensate hypertension. These data suggests that BP should be regulated by feedback and local mechanisms homeostatically for saving life and by feedforward mechanisms homeodynamically for helping organ-functions. [J Physiol Sci. 2006;56 Suppl:S25]