Effect in the Conscious Dog of Constriction of the Renal Artery to a Sole Remaining Kidney on Haemodynamics, Sodium Balance, Body Fluid Volumes, Plasma Renin Concentration and Pressor Responsiveness to Angiotensin

Abstract

1.The renal artery to a lone remaining kidney was constricted in fourteen concious dogs. The following variables were measured in all animals: blood pressure (BP), cardiac rate (CR), plasma renin concentration (PRC), plasma volume (PV), extracellular fluid volume (ECFV) and plasma non-protein nitrogen (NPN). Sodium balance was estimated in eleven dogs. Cardiac output (CO), total peripheral resistence (TPR) and stroke volume (SV) were measured in nine dogs. Angiotensin responsiveness (AR) was measured in six animals.2. Within 2 hr the following changes occurred: a sharp increment of BP, PRC and TPR, with initial reduction or no change in CO and CR; SV and PV were not changed. The linear regression of BP changes on PRC changes did not differ statistically from the one previously obtained during the infusion of exogenous renin in the conscious dog. AR was much depressed at 2 hr.3. After 24 hr a slight but sigdicant sodium retention developed, while PV and ECFV and SV increased, CO remained unchanged owing to a decrease of CR. PRC tended to return toward normal while BP remained high. Thus the linear regression between these two variables disappeared. At this stage AR increased toward normal and in two dogs exceeded normal. 4.On days 3 4 and 6-7 after constriction, CO increased owing to a rise of SV, while TPR decreased. PV and ECFV were expanded while sodium balance was maintained. AR varied very much in the individual dogs according mainly to changes of PRC, sodium balance and PV. 5. On days 12-14 sodium balance became positive again, PRC returned within normal levels in almost all the dogs. PV and ECFV also tended to decrease to normal.CO and AR were measured in only two dogs at this stage.6. It is suggested that the early rise of blood pressure might be produced by the

Acute effects of captopril on blood pressure and regional blood flows in two types of renovascular hypertensive rats in conscious state.

“…It is well known that though the renin-angiotensin system contributes to the development of hypertension in the early stage of one-kidney hypertensive animals, the maintenance of hypertension in the chronic phase is mainly due to expansion of fluid volume resulting from directly decreasing renal function (BIANCHI et at., 1970). Our results may also suggest on the basis of these quoted papers that the reninangiotensin-mediated vasoconstriction does not play a major role in maintaining one-kidneyy hypertension in the chronic stage.…”

“…been reported that the elevated arterial pressure at the onset of one-kidney renovascular hypertension is initially due to the renin-angiotensin-system-mediated vasoconstriction (HELMCHEN et al, 1972); and subsequently the fluid volume expansion replaces increased plasma renin activity as the cause of the elevated arterial pressure (LEDINGHAM and CoHEN, 1964;BIANCHI et al, 1970).…”

Angiotensin II, aldosterone and arterial pressure: a quantitative approach. Arthur C. Corcoran Memorial Lecture.

“…113 There is.general agreement that within hours of applying a renal artery clamp, peripheral blood levels of renin are raised. Subsequently, although arterial pressure remains elevated, renin levels are proportionately lower.…”

Time Course Study of Body Fluid Volumes in Two-Kidney, One-Clip and One-Kidney, One-Clip Hypertension in Rats

“…There have been several studies measuring plasma volume (PV) and/or extracellular fluid volume (ECE) with these experimental models. On days earlier than the 7th day, after renal artery stenosis in one-kidney, one-clip hypertension, PV and/or ECE were reported to be increased in most studies [1][2][3][4][5]. On days later than the 14th day, the results were still are controversial ; the increased body fluid volumes were observed in some studies [6,7], but not in others [1,4,5].…”