Dietary protein restriction and renal injury in the spontaneously hypertensive rat

We examined the influence of a low-protein diet on the course of the renal injury in spontaneously hypertensive rats (SHR) and SHR given antihypertensive drug therapy (SHRD). Antihypertensive drug treatment was hydralazine, reserpine, and chlorothiazide. Wistar-Kyoto (WKY) rats served as normotensive controls. SHR, SHRD, and WKY were each placed on a 24, 14, and 10% protein diet at 5 wk and followed to 80-90 wk of age. Untreated SHR showed a steady rise in protein excretion from 5 to 70 wk regardless of dietary protein content. Protein excretion in SHRD on a 24% protein diet was similar to untreated SHR. However, SHRD on a 14 or 10% diet had a more moderate increase in protein excretion. Glomerular, tubular, and vascular pathology in untreated SHR was not influenced by dietary protein intake. Despite successful antihypertensive therapy, kidney pathology in SHRD on a 24% diet was not significantly different from untreated SHR. In contrast, SHRD on 14 or 10% protein diets had less segmental glomerulosclerosis and vascular pathology than untreated SHR. The results indicate that dietary protein restriction does not influence the course of renal injury in untreated SHR. However, the combination of antihypertensive drug therapy with protein restriction in SHR delays and may arrest progression of glomerulosclerosis and proteinuria.