Glomerulotubular balance in hypertensive rats.

The relationship between glomerulotubular balance and the development of hypertension was studied in subtotally nephrectomized rats, with or without previous chronic salt loading, 1-4 weeks after the operation. The creatinine clearance (Ccr) was similarly reduced in all the groups as compared to control rats. The maximal glucose reabsorption (TmGlc) was also decreased in all experimental groups with the sole exception of saline-loaded hypertensive rats in which the fall did not reach the significance level. The ratio TmGlc/Ccr, which was taken as an index of glomerulotubular balance, was high in the hypertensive groups and further enhanced by saline loading. Peak values of TmGlc/Ccr were detected in the 1st week after operation and declined thereafter reaching normal levels in the hypertensive rats but not in the hypertensive saline-loaded animals. Results suggest that an early glomerulotubular imbalance is some way related to the development of hypertension in subtotally nephrectomized rats. This abnormality is apparently corrected by the counterbalancing effect of increased renal perfusion pressure but can be unmasked by saline loading.