Influence of the renin—angiotensin system on the autoregulation of renal blood flow and glomerular filtration rate in conscious dogs

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Abstract
Renal autoregulation of blood flow (RBF) and glomerular filtration rate (GFR) were examined in 10 conscious foxhounds under a normal sodium diet before and after a continuous intrarenal converting—enzyme inhibition (CEI) or during the application of the angiotensin II antagonist saralasinm®. In order to prevent α‐adrenergic interference, phenoxybenzamine was infused into the renal artery. In contrast to studies performed in salt depleted dogs there was no impairmentof RBPorGFRautoregulation after CEI or saralasin®. Renal blood flow was autoregulated at a level of 3.81 ± 0.18 ml min‐1g‐1in the control group, 3.98 ± 0.16 ml min‐1g‐1after CEI and 3.97 ± 0.41 ml min‐1g‐1after saralasin®. The lowest point of autoregulation was very much the same between the individual groups (control: 65.0 ± 1.4 mmHg; CEI: 66.5 ± 4.6 mmHg; saralasin®: 67.4 ± 3.2 mm Hg).GFRacted in a similar manner (autoregulation level control: 0.50 ± 0.03 ml min‐1g‐l; CEI: 0.52 ± 0.05 ml min‐1g‐1; saralasin®. 0.50 ± 0.04 ml min‐1g‐1). The lowest pressure ofGFRautoregulation differed slightly more (control: 81.5 ± z. z mmHg; CEI: 93.2 ± 4.2 mmHg; saralasin®: 85.9 ® 2.1 mmHg). The results suggest that the renal autoregulationof GFRandRBFis independent of the renin‐angiotensin system in conscious dogs during a normal sodium diet.