[en] Diuresis and natriuresis following APs has been suggested to depend upon increased renal blood flow (RBF). In a previous study, they found that APII infusions in conscious SHR decrease RBF. In this study, they report effects of APII on glomerular filtration rate (GFR) and renal excretory function in conscious SHR. Male SHR were equipped with arterial and venous catheters. Furthermore, a special catheter was implanted into the bladder to allow continuous urine sampling from conscious, freely moving rats. Animals were allowed at least 4 days to recover. In one group of SHR, APII (N=7) or saline (N=7) was infused to quantitate excretion of water, Na⁺, and K⁺. Two other groups of SHR (N=8 each) were infused with ⁵¹Cr-EDTA and ¹²⁵I-PAH. GFR and renal plasma flow (ERPF) were calculated from urine and a mid-time plasma sample during APII or saline infusion. Following changes in infusion rates, urine from the first 5 min was discarded, after which a 10-min collection was made. APII (0.5-4 μg/kg/min) increased water, Na⁺ and K⁺ output maximally during 2 μg/kg/min. ERPF decreased from 10.7 +/- 1.1 ml/min to 7.9 +/- 0.5 ml/min. GFR did not change significantly. Filtration fraction increased from 24 +/- 1% to 33 +/- 2%. Fractional water excretion increased from 0.8 +/- 0.2% to 2.5 +/- 0.7%. Saline infusions did not affect renal function. The results indicate that in conscious SHR, APII causes diuresis and natriuresis which does not depend upon increased GFR, but, rather, upon a primary tubular effect