Effect of barbiturates on GFR and fluid reabsorption along proximal convoluted tubules and loops of henle in rats

Summary In the present study we investigated the possibility that GFR and fluid reabsorption are systematically altered by dose and/or structure of different barbiturate compounds. The results show that filtration and absorption rates are identical in rats anaesthetized with 100 or 150 mg/kg BW. Elevating the administered amount by intravenous injections of inactin did not alter renal functions compared to values measured immediately before the additional administration. No differences of GFR and absorption rates were noted when the effect of inactin, amytal, and nembutal in doses necessary to induce and maintain anaesthesia was compared. Absolute and fractional absorption was observed to decrease by 20 to 25% in the first 3 h after induction of anaesthesia independent of the anaesthetic used. Our results suggest that filtration and absorption rates are not systematically modified by specific anaesthetic effects, at least not when doses are kept close to the necessary minimum.Work performed during tenure of an Alexander von Humboldt-Dozentenstipendium.