AJP - Renal Physiology, Vol 233, Issue 2 102-F117, Copyright © 1977 by American Physiological Society
Evidence for glomerular actions of ADH and dibutyryl cyclic AMP in the rat
I. Ichikawa and B. M. Brenner
Experiments were performed on 54 chronically water diuretic Munich-Wistar
rats to investigate the effects of various antidiuretic peptides on the
determinants of glomerular ultrafiltration. Transition from water diuresis
to antidiuresis, induced either by intravenous infusion of 1) exogenous
peptides (Pitressin, synthetic arginine vasopressin, or synthetic
[1-deamino,4-valine]-8-D-arginine vasopressin) or 2) dibutyryl cyclic AMP,
or by stimulation of endogenous ADH release by acute, mild arterial
hemorrhage, was associated with near-constant or decreased values for
single nephron (SN) and total kidney GFR. Nevertheless, the glomerular
transcapillary hydraulic pressure difference (deltaP) uniformly increased
with antidiuresis, due to consistent reductions in Bowman's space hydraulic
pressure rather than to increases in glomerular capillary hydraulic
pressure, the former a consequence of the fall in urine flow rate. In all
antidiuretic states, the rats were uniformly observed to be at filtration
pressure disequilibrium, permitting calculation of unique values of the
glomerular ultrafiltration coefficient (Kf). These values of Kf in
antidiuresis were invariably lower than the values obtained during water
diuresis. Whether these effects of ADH and DBcAMP on deltaP and Kf
represent physiological influences in the control of GFR remains uncertain;
their offsetting effects in the present studies usually failed to alter GFR
appreciably.
