Norepinephrine and renal functions in dogs given Russell's viper venom

Abstract

This investigation was performed to study the effects of Russell’s viper venom (RVV) on plasma norepinephrine level relating to renal functions in dogs pretreated with ∝₁-adrenergic blocker (prazosin) or converting enzyme inhibitor (enalapril maleate) or cyclooxygenase inhibitor (indomethacin). RVV produced an elevation in plasma norepinephrine level within 10 minutes after envenomation in animals given intravenously placebo (group I), but was not apparent in envenomated animals pretreated with prazosin (group II), enalapril maleate (group III) and indomethacin (group IV). The reduction of renal plasma flow (RPF), renal blood flow (RBF), a glomerular filtration rate (GFR) and the elevation of renal vascular resistance (RVR) were observed in envenomated animals of group I. In group II and III the RVR decreased after envenomation while RVR in group IV increased rapidly as compare to animals in group I. Urine flow rate decreased after envenomation in all groups, but anuria was apparent in group I and IV in the first 30 minutes following venom injection. The reduction in fractional sodium excretion (FE [subscript Na]) and the elevation in fractional potassium excretion (FE [subscript k]) were apparent in all groups. These results may suggest that prostaglandins, rennin-angiotensin system and ∝₁-adrenergic receptor are involved in modulating of changes in circulating norepinephrine levels and renal functions in dogs after envenomation. The reduction of plasma norepinephrine level and improvement of renal functions of envenomated animals occur in animals pretreated with either prazosin or enalapril maleate.