The effect of unilateral renal ischaemia on fluid turnover in rats.

Abstract

SummaryModifications in fluid handling occur in rats following the induction of unilateral renal ischæmia, even though the other kidney remains intact. Some animals develop extreme degrees of polydipsia and polyuria. Amongst those drinking 0.5 % saline, “polydipsia”, defined as an intake more than three times the original, was observed during an observation period of four weeks in 16%. Amongst animals drinking water, this degree of increase in fluid turnover was observed in only 4%.Apart from these animals, spontaneous fluid turnover was not demonstrably greater than that which could have been accounted for by diminution in functioning renal tissue consequent upon the induction of ischæmia. Alterations in fluid handling in these animals attributable to the hypertension are, however, demonstrable by measurement of the rate of rejection of an orally administered fluid load. Following the induction of ischæmia, rejection of both saline and water was greater than either before this procedure or after removal of the ischæmic kidney, and the degree of increase in both groups was the same.Histological examination of the kidneys showed a close correlation between the onset of polydipsia and polyuria and the development of malignant hypertensive changes in the intact kidney.Markedly increased fluid turnover apparently indicating the supervention of the malignant phase is described in a patient with unilateral renal disease, and the literature on this type of case is briefly reviewed.