AJP - Renal Physiology, Vol 250, Issue 2 256-F260, Copyright © 1986 by American Physiological Society
Effect of secretin on glomerular dynamics in dogs
G. R. Marchand
These studies were performed to determine whether a role for increased
renal plasma flow (RPF) in the regulation of glomerular filtration rate
(GFR) could be demonstrated in dogs by infusing the polypeptide hormone
secretin, a vasodilator that has been reported to increase GFR. Differences
between control and recollection periods were compared by paired t test in
five time-control dogs (group 1) and 10 secretin dogs (group 2). In group
2, secretin (100 mU . kg-1 . min-1, ia) significantly increased
single-nephron glomerular filtration rate (SNGFR) 11.1 +/- 3.1 nl/min (20%)
and glomerular plasma flow 59 +/- 11 nl/min (26%). Similar increases in GFR
(26%) and RPF (29%) were observed. Secretin also increased glomerular
capillary pressure 5.2 +/- 0.8 mmHg and free-flow proximal tubule pressure
5.5 +/- 1.0 mmHg. Secretin did not significantly affect average effective
filtration pressure (EFP) but significantly increased the ultrafiltration
coefficient (Kf) 0.74 +/- 0.14 nl . min-1 . mmHg-1. These differences were
significantly greater than those observed in group 2. It is concluded that
secretin increased SNGFR primarily by an effect on Kf. This is consistent
with the marked effect that Kf is predicted to have on glomerular
filtration in dogs. The maintenance of EFP agrees with other vasodilator
studies and indicates that GFR is only moderately dependent on plasma flow
in dogs.
