Sodium Depletion Proteinuria: Experimental and Electronmicroscopic Studies 1 2

Summary

Female Wistar rats were submitted to peritoneal dialysis with either a balanced ionic solution (control group), or a solution which was identical except that it was deficient in sodium (sodium depleted). The 24-hr urine protein excretion on the day before dialysis was compared to that on the day after dialysis. Kidney specimens were taken for morphologic study by light and electron microscopy at the end of urine collections to correlate any structural changes with the degree of protein excretion.

Nineteen out of 37 sodium depleting dialyses were followed by a threefold, or greater, increase in urine protein excretion while 0 out of 33 control dialyses were followed by an equivalent increase. Quantitatively there was a highly significant increase (p < 0.001) in urinary protein excretion following the sodium depleting dialyses as compared to the control dialyses.

Study of the kidneys by electron microscopy showed definite ultrastructural changes in those animals which showed an increase in urinary protein excretion while no changes were seen either in animals submitted to control dialysis or in sodium-depleted animals which failed to show an increase in urinary protein excretion.

The results confirm that sodium depletion can induce proteinuria in the rat. The ultrastructural changes in the glomeruli are interpreted as secondary to proteinuria.