Autoregulatory capacity in renal and mesenteric vasculatures of mineralocorticoid hypertensive dogs.

Experiments were performed in seven conscious dogs to quantitate the renal and mesenteric autoregulatory capacity in deoxycorticosterone acetate (DOCA)-salt hypertensive dogs. Each dog was chronically instrumented for the measurement of aortic blood pressure and blood flows through the superior mesenteric and left renal arteries (Doppler measurements); a right nephrectomy was also performed. To induce hypertension, animals were administered 5 mg/kg DOCA each day and given 1% saline as a drinking solution. After arterial pressure had increased by 25% (8-14 days of DOCA), a large-bore catheter was positioned retrograde in the left common carotid artery for subsequent connection to a gravity reservoir system for acute control of arterial pressure. Autoregulatory capacity was evaluated by controlling arterial pressure via the gravity reservoir at hypertensive and then normotensive values for 15-min periods. In neurally intact animals the renal, but not the mesenteric, circulation displayed autoregulatory capacity; the closed-loop gain of renal flow control averaged 0.92 +/- 0.06. Inhibition of autonomic ganglionic transmission (hexamethonium) increased the gain of flow regulation in the mesenteric circulation, but mesenteric autoregulation was not manifest. Ganglionic blockade, inhibition of prostaglandin formation, or blockade of histamine or adenosine receptors did not significantly influence renal autoregulatory capacity. These data demonstrate that the kidney has a high capacity to autoregulate in DOCA hypertension and suggest that autoregulatory-mediated renal vasoconstriction contributes to the increased total peripheral resistance.