Effect of blood pressure on the progress of renal deterioration in rats with renal mass reduction.

The effect of hypertension on the progress of renal deterioration with renal mass reduction was investigated in spontaneously hypertensive rats. Nephrectomies of five sixths, two thirds, and one third were performed. The antihypertensives guanethidine and hydralazine were given to half of the rats. Increase in urinary protein excretion and decreases in serum total protein and albumin were greater in rats with a larger nephrectomy. With the same extent of nephrectomy, these changes were severe in the group of rats with untreated hypertension, as compared with findings in rats given the antihypertensive drugs (AHD). Similar changes were obtained in BUN and creatinine levels. Only the animals with a five-sixths nephrectomy and hypertension became uremic. Glomerulosclerosis in five-sixths nephrectomized rats with hypertension was present in 71% of the glomeruli, whereas it was reduced to 34% in rats treated with AHD. The diameter of normal-appearing glomeruli increased significantly in rats with a large nephrectomy, but did not differ between the groups given or not given AHD. Medical thickening of the arterial walls, which increased with the reduction of renal mass, was significantly greater in five-sixths nephrectomized rats with hypertension than in those treated with AHD. These results indicate that a hyperdynamic state of the glomeruli, that is, a prominent urinary protein excretion and compensatory glomerular hypertrophy, may play a causative role in the progress of glomerulosclerosis in rats with extreme renal mass reduction. The hypertensive state may aggravate these renal dysfunctions.