VASCULAR AND TUBULAR ACTIONS OF DIAZEPAM IN ISOLATED AND PERFUSED RAT-KIDNEY

The effects of diazepam were studied in the isolated rat kidney under conditions of constant flow. Kidneys were perfused with modified Ringe r-Krebs solution. Diazepam produced a raised fractional excretion of w ater and sodium without hemodynamic changes, suggesting a direct effec t on tubular transport mechanisms. Diazepam decreased renal perfusion pressure in a concentration-dependent fashion when kidneys were pretre ated with either noradrenaline or potassium chloride. Similar response s were observed when 7-chloro-5-[4-chloro-phenyl]-1,3-dihydro H-1,4-be nzodiazepin-2-one (Ro 5-4864) or clonazepam was used. These data provi de evidence for a relaxant effect of benzodiazepines on preconstricted renal vasculature.