AJP - Cell Physiology, Vol 258, Issue 2 C243-C247, Copyright © 1990 by American Physiological Society
Evidence for chloride secretion in the intestine of the winter flounder
S. M. O'Grady and P. J. Wolters
Department of Veterinary Biology, University of Minnesota, St. Paul 55108.
The effects of a novel antisecretory peptide (CAP) isolated from porcine
heart and vasoactive intestinal peptide (VIP) on ion transport were
investigated in the winter flounder intestine. Partially purified CAP
caused a two- to sixfold increase in the serosa-negative short-circuit
current (Isc) with no significant change in tissue conductance. CAP
significantly inhibited the serosal-to-mucosal (S-M) unidirectional Cl flux
without affecting either Na or Rb transepithelial fluxes. The Isc after the
addition of CAP was completely inhibited by 0.1 microM atriopeptin III
(AP-3), 10 microM bumetanide, and 100 microM 8-bromoguanosine 3',5'-cyclic
monophosphate (8-BrcGMP). In contrast to the effects of CAP on Isc, VIP
decreased the serosa-negative Isc by 40-60%. VIP stimulated the S-M
unidirectional Cl flux without affecting transepithelial Na transport. When
food was present in the intestine, the basal Isc was occasionally found to
be serosa positive, ranging between 10 and 40 microA/cm2. Treatment of
tissues exhibiting serosa-positive currents with VIP resulted in an
increase (positive direction) in Isc. Addition of CAP to tissues with a
serosa-positive Isc or to tissues pretreated with VIP resulted in a
serosa-negative Isc.(ABSTRACT TRUNCATED AT 250 WORDS)
