AJP - Renal Physiology, Vol 244, Issue 5 483-F487, Copyright © 1983 by American Physiological Society
Autoregulation of renal blood flow in the rat: effects of growth and uninephrectomy
R. L. Chevalier and D. L. Kaiser
As a result of normal maturation or after reduction in renal mass, renal
blood flow (RBF) progressively increases. However, the effects of renal
growth on the relationship of RBF to renal perfusion pressure (RPP) have
not been systematically investigated. We examined RBF as a function of RPP
in anesthetized young and adult rats that had been subjected to
uninephrectomy or sham operation 3-4 wk previously. As a result of normal
growth, mean arterial blood pressure increased from 94.1 +/- 2.7 (SE) to
118.9 +/- 4.2 mmHg. The calculated autoregulation factor, in which a value
less than 1 indicates the presence of autoregulation, was 0.44 +/- 0.10
over RPP 70-100 mmHg and 1.74 +/- 0.25 over RPP 40-70 mmHg in sham-operated
young animals. In adult sham-operated rats, the factor was 0.38 +/- 0.07
over RPP 100-130 mmHg and 1.03 +/- 0.07 over RPP 70-100 mmHg.
Uninephrectomy in adults resulted in a 30% rise in RBF over RPP 100-130
mmHg, and there was no change in the autoregulation factor. Uninephrectomy
in young rats, however, resulted in a 35% rise in RBF at RPP = 100 mmHg
with only a 17% rise at RPP = 70 mmHg, and the autoregulation factor
increased to 0.91 +/- 0.10 over this range of RPP. We conclude that the
autoregulatory range shifts with increasing blood pressure during normal
growth and that autoregulation is "reset" to higher RBF in the
uninephrectomized adult rat. Although autoregulation takes place in the
young animal, uninephrectomy alters the relationship of RBF to RPP such
that autoregulation is impaired.
