The Relationship of the Juxtaglomerular Apparatus to Sodium Retention in Experimental Nephrosis

Abstract

The granular juxtaglomerular cells were studied during the renal retention of sodium associated with experimental nephrosis. A number of rats were given a standard regimen of aminonucleoside in order to produce the nephrotic syndrome. They exhibited widely varying degrees of sodium retention. After 18 days the rats were killed, the amount of ascites was measured, and kidney tissue was obtained for specific staining and quantitation of juxtaglomerular granules. The rats were divided into 2 groups. Each of the 32 rats in one group had between 4 and 30 milliliters of ascitic fluid; the 28 rats in the other group had between 0 and 1 milliliters. The group with considerable ascites had an average juxtaglomerular index of 33, while that for the group with minimal ascites was 21. This different is highly significant. For each rat in the 2 groups the juxtaglomerular index was plotted on a scatter diagram in relation to the amount of ascites. The coefficient of correlation between these 2 variables was +0.72, a highly significant degree of correlation. Thus, the greater the degree of sodium retention, the more abundant the juxtaglomerular granules will be. The increased granularity in all likelihood represents hypersecretion of the juxtaglomerular cells. This hypersecretion probably plays an important part in the mechanism of sodium retention in the nephrotic syndrome.