Renal blood flow and function in the rabbit after surgical trauma. II. The role of constriction in the main renal artery and activation of the alpha-adrenergic receptors.

The impairment of renal circulation and function in connection with general anaesthesia and surgical trauma was investigated in 19 rabbits. The systemic circulation and the renal circulation were evaluated by a dye-dilution technique and glomerular and tubular function by measuring the extraction of 51-Cr-EDTA and 125-I-Hippuran. In Group I measurements were performed before and after manipulation of the left renal artery preceded by topical application of a local anaesthetic. In Groups II and III measurements were performed before and after i.v. injection of, respectively, 0.8 and 3.0 mg/kg body-weight phenoxybenzamine, and then after manipulation of the renal artery. Blockade of the alpha-adrenergic receptors with phenoxybenzamine was found to preserve the renal fraction of the cardiac output. The blockade prevented an initial reduction in the extraction of EDTA and Hippuran, previously ascribed to general anaesthesia, but did not prevent a diminution following surgical handling of the kidney and the renal artery. The local anaesthesia had no effect. It is concluded that general anaesthesia and surgical trauma cause an impairment of the renal circulation due to an increased concentration of plasma catecholamines.