Effects of plasmapheresis on renal hemodynamics and sodium excretion in dogs

Summary Acute plasmapheresis in dogs reduces plasma protein concentration, without significantly altering plasma volume, glomerular filtration rate and plasma sodium concentration.The effects of acute hypoproteinemia on renal circulation is variable. In some cases, the renal plasma flow is not modified, while in others it is markedly decreased, leading to a rise in filtration fraction. The hemodynamic changes are observed in experiments inducing marked protein depletion.Acute hypoproteinemia increases sodium excretion exclusively in experiments where plasmapheresis has not reduced kidney irrigation.The lack of plasma volume expansion in the natriuretic animals cancels the necessity of postulating the secretion of some unknown natriuretic hormone to explain the decreased tubular reabsorption of sodium. The explanation of saline diuresis should be sought within the kidney itself, and the fall in peritubular oncotic pressure, occurring after plasmapheresis or during massive saline loading, offers an alternative explanation, which appears simpler and more rational.