The effect of surgical trauma, ischaemia and ureteral occlusion on renal blood flow and function. An experimental study in the rabbit.

The influence of surgical trauma on renal blood flow and renal function was examined in lightly anaesthetized rabbits. The renal vessels were catheterized and the dye-dilution technique was used to measure renal blood flow and cardiac output. The renal fraction of the cardiac output, the total peripheral vascular resistance, and the renal vascular resistance were calculated. Glomerular and the tubular function was evaluated by measuring the extractions of 51Cr-EDTA and of 125I-Hippuran. A decrease in cardiac output was accompanied by a diminution in renal blood flow. The renal blood flow and the renal fraction of the cardiac output were reduced initially, regardless of whether surgery or puncture of the kidney were performed. When the alpha-adrenergic receptor sites were blocked with phenoxybenzamine, however, the renal fraction of the cardiac output remained stable. It was therefore, concluded that during general anaesthesia the sympathetic tonus or the concentration of plasma catecholamines increased, causing vasoconstriction in the kidney. Manipulation of the renal artery seemed to stimulate vasoconstriction in the ipsilateral kidney by a direct effect. Localized spasm of the main renal artery cannot be assumed to have caused alterations in the renal blood flow and the renal fraction of the cardiac output, as prevention of spasm by topical application of local anaesthesic did not offer protection against these alterations. A decrease in glomerular and tubular function occurred initially, indepently of surgical trauma, but could be prevented by blockade of the alpha-adrenergic receptors sites. This argues for a renal vasoconstriction including the afferent arterioles. Renal function was not much influenced by traumatization of the renal artery. A reduction in function was, however, seem when the traumatization was preceded by topical application of a local anaesthetic or by blockade of the alpha-adrenergic receptors sites. This findings seems difficult to explain. The renal artery was occluded for varying lengths of time with the aid of a balloon catheter, and the effect of temporary ischaemia on renal blood flow and function was examined. Prolongation of the period of continuous ischaemia from 15 to 60 minutes resulted in a progressive increase in the postocclusive hyperaemia, but in a successive reduction in the renal function. Compared with 30 minutes of continuous occlusion, 30 minutes of intermittent occlusion caused slight hyperaemia, but the same degree of reduction in renal function. One day after 30 minutes or 60 minutes of ischaemia, renal blood flow was within the range of normal flow. After 30 minutes of occlusion, renal function was re-established seven days later, whereas after 60 minutes of ischaemia, function was still severly impaired. Fourteen days after 60 minutes of occlusion, renal function was partly restored, being 50% or less of the normal. No juxtamedullary shunting of importance could be demonstrated in the present investigation...