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The acute renal effects of intravenous tertatolol were studied in eight patients with moderate essential hypertension: the study included a 100 mmol/day sodium intake during 3 days. Then, tertatolol was infused after a water load during 2 consecutive periods of 30 min (priming dose followed by constant infusion) in order to obtain plasma concentrations of tertatolol at 2 different levels: 10 ng/ml, then 40 ng/ml successively; the measurements were obtained at 15, 30, 45 and 60 min. The renal plasma flow (RPF) and the glomerular filtration rate (GFR) were calculated from the 131I-Hippuran clearance and the 125I-Iothalamate clearance respectively; a bladder catheter allowed a precise urine collection. The results indicate that intravenous tertatolol, at low dose, induced a marked and early renal vasodilatation; higher dose of tertatolol attenuated the vasodilator response, probably because of a decrease in cardiac output (suggested by the decrease in heart rate); thus, the systemic effects would hide the direct renal hemodynamic effects of tertatolol. Natriuresis and kaliuresis were unchanged by intravenous tertatolol. |
