高血圧の臓器循環 ： 低酸素負荷による検討

Abstract

In order to investigate the pathophysiological mechanism of hypertension, a comparative study was performed on the cardiovascular resposes to acute systemic hypoxia between two groups, hypertensive dogs (two-kidney, one-clip renovascular) and normotensive controls. During hypoxia induced by breathing a mixed gas of 5% O＿2 and 95% N＿2 with artificial ventilation, systemic and regional hemodynamics were measured using an electromagnetic flowmeter and a pressure transducer. The following results were obtained in hypertensive dogs. (1) Cardiac output and arterial blood pressure increased, but these increases were inhibited by the previous administration of hexamethonium (C＿6). (2) Carotid blood flow also increased, but was not affected by either previous administration of C＿6 or continuous infusion of captopril. (3) Renal blood flow almost did not change, but increased by pretreatment with C＿6. (4) Femoral blood flow increased, but was suppressed by both previous administration of C＿6 and following administration of propranolol. These findings suggest that the cardiovascular responses to acute systemic hypoxia of the hypertensive group differ from those of the normotensive group, and interactions among the sympathetic nervous system, renin-angiotensin system, autoregulation of regional blood flow and β-adrenergic receptor activity may play an important role in the pathogenesis of hypertension.