Mechanisms of hypertension during the acute and intermediate phases of the one-clip, two-kidney model in the dog.
The acute and intermediate onset phases of one-clip, two-kidney hypertension were studied in six conscious dogs. Mean arterial pressure (MAP), cardiac output (CO), total peripheral resistance (TPR), serum renin concentration (SRC), plasma aldosterone (PA) and cumulative sodium and water balance were studied prior to unilateral renal artery constriction, at 2, 10, and 24 hours postconstriction, and daily thereafter for 5 days. At 2 hours postconstriction, MAP, CO, TPR, and SRC were elevated, with unchanged fluid balance. At 10 and 24 hours there was a further rise in CO accompanied by positive fluid-sodium balance, with a slight decrease in MAP, TRP, and SRC. During days 2 and 3, MAP, CO, TPR, and SRC remained elevated and stable in the presence of decreasing fluid-sodium balance to preconstriction levels. During days 4 and 5, MAP, SRC, and fluid-sodium balance remained unchanged, TPR demonstrated a secondary increase, whereas CO decreased to preconstriction values. Sequential changes in PA parallel those of SRC, but were significant only at 2 hours postconstriction. These changes suggest that the increased CO is not totally dependent on fluid-sodium balance, and that CO is not the sole determinant of elevated MAP. The temporal relationship between MAP and SRC throughout the study is consistent with renin-mediated hypertension. The secondary rise of TPR may be due to total body autoregulation and/or increased vascular reactivity to high levels of circulating angiotensin. A unitary renin-angiotensin mechanism, therefore, may be responsible for the induction and maintenance of hypertension in this experimental model.
D000208:Acute Disease; D000450:Aldosterone / Q000097:blood; D000818:Animals; D001794:Blood Pressure; D004195:Disease Models, Animal; D004285:Dogs; D006439:Hemodynamics; D006977:Hypertension, Renal / Q000097:blood / Q000503:physiopathology*; D008722:Methods; D012078:Renal Artery Obstruction / Q000503:physiopathology*; D012083:Renin / Q000097:blood; D012964:Sodium / Q000097:blood; D014882:Water-Electrolyte Balance
D000450:Aldosterone; D012964:Sodium; D012083:Renin