Abstract
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 (I(sc)) 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 I(sc) after the addition of CAP was completely inhibited by 0.1 μM atriopeptin III (AP-3), 10 μM bumetanide, and 100 μM 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP). In contrast to the effects of CAP on I(sc), VIP decreased the serosa-negative I(sc) 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 I(sc) was occasionally found to be serosa positive, ranging between 10 and 40 μA/cm2. Treatment of tissues exhibiting serosa-positive currents with VIP resulted in an increase (positive direction) in I(sc). Addition of CAP to tissues with a serosa-positive I(sc) or to tissues pretreated with VIP resulted in a serosa-negative I(sc). From these results it was concluded that 1) CAP and VIP regulate a Cl secretory pathway present in the intestinal epithelium of the winter flounder, 2) VIP acting through adenosine 3',5'-cyclic monophosphate (cAMP) activates Cl secretion which results in a decrease in the serosa-negative I(sc) observed with these secretagogues, 3) CAP acts through an unknown mechanism to inhibit Cl secretion, and 4) in flounder that have been fasted for 3 days or more, the rate of basal Cl secretion appears to decrease and the magnitude of the serosa-negative I(sc) is much greater than in nonfasted animals.
Original language | English (US) |
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Pages (from-to) | C243-C247 |
Journal | American Journal of Physiology - Cell Physiology |
Volume | 258 |
Issue number | 2 27-2 |
State | Published - Mar 20 1990 |
Keywords
- adenosine 3',5'-cyclic monophosphate
- atrial natriuretic factor
- cardiac antisecretory peptide
- guanosine 3',5'-cyclic monophosphate
- ion transport
- sodium-potassium-two chloride cotransport