Beschreibung:
<jats:p>Infusion of substance P into the renal artery was previously shown to cause a significant natriuresis which was associated with increased kallikrein excretion. Since the renal kinin and prostaglandin (PG) systems may be interrelated, the present study was performed to investigate the effects of substance P on renal function and its potential interaction with the renal PG system in the conscious rat. 24 female Sprague-Dawley rats were infused intravenously with substance P (1 ng · min<sup>-1</sup> · kg<sup>-1</sup> body weight) and the body weight was kept constant by an intravenous infusion of 0.45% saline. Substance P had no effects on arterial blood pressure, glomerular filtration rate (GFR) and <sup>125</sup>I-hippuran clearance in the absence or presence of indomethacin (INDO). Basal U<sub>PGE2</sub> V was unaltered by substance P infusion but was suppressed by INDO before and during substance P by 80 and 88%, respectively. Substance P raised urinary flow rate (V) by 105%, C<sub>H2O</sub> by 96%, U<sub>Na</sub>V by 378%, U<sub>K</sub>V by 48% and U<sub>PO4</sub>V by 147% (p < 0.001). Although INDO significantly suppressed V, C<sub>H2O</sub>, and U<sub>Na</sub>V during all collection periods, it did not affect absolute U<sub>PO4</sub>V and U<sub>K</sub>V and the relative rise in V, C<sub>H2O</sub>, and U<sub>Na</sub>V induced by substance P. Thus, the diuretic and natriuretic effects of substance P are not mediated by renal PG, but are partially blunted by INDO through increased distal absorption of sodium and water, INDO has no effect on substance P-induced alterations in proximal tubular function.</jats:p>