Role of the vasopressin V(1) receptor in regulating the epithelial functions of the guinea pig distal colon.
Vasopressin has a wide spectrum of biological action. In this study, the role of vasopressin in regulating electrolyte transport in the colon was elucidated by measuring the short-circuit current (I(sc)) as well as the Na(+), K(+), and Cl(-) flux in a chamber-mounted mucosal sheet. The cytosolic Ca(2+) concentration ([Ca(2+)](i)) was also measured in fura 2-loaded cells by fluorescence imaging. Serosal vasopressin decreased I(sc) at 10(-9) M and increased I(sc) at 10(-7)-10(-6) M. The decrease in I(sc) was accompanied by two effects: one was a decrease in the amiloride-sensitive Na(+) absorption, whereas the other was an increase in the bumetanide-sensitive K(+) secretion. The increase in I(sc) was accompanied by an increase in the Cl(-) secretion that can be inhibited by serosal bumetanide or mucosal diphenylamine-2-carboxylate. Vasopressin caused an increase in [Ca(2+)](i) in crypt cells. These responses of I(sc) and the [Ca(2+)](i) increase in crypt cells were all more potently inhibited by the vasopressin V(1) receptor antagonist than by the V(2) receptor antagonist. These results suggest that vasopressin inhibits electrogenic Na(+) absorption and stimulates electrogenic K(+) and Cl(-) secretion. In all of these responses, the V(1) receptor is involved, and the [Ca(2+)](i) increase may play an important role.
Sato
Y
Y
First Department of Medicine, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan. ysato826@hama-med.ac.jp
Hanai
H
H
Nogaki
A
A
Hirasawa
K
K
Kaneko
E
E
Hayashi
H
H
Suzuki
Y
Y
D000042:Absorption / Q000187:drug effects; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002034:Bumetanide / Q000494:pharmacology; D002118:Calcium / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism; D003106:Colon / Q000187:drug effects / Q000502:physiology*; D004553:Electric Conductivity; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000187:drug effects / Q000502:physiology*; D017136:Ion Transport / Q000502:physiology; D008297:Male; D011188:Potassium / Q000378:metabolism; D020033:Protein Isoforms / Q000502:physiology; D017483:Receptors, Vasopressin / Q000502:physiology; D012964:Sodium / Q000378:metabolism
D002712:Chlorides; D020033:Protein Isoforms; D017483:Receptors, Vasopressin; D002034:Bumetanide; D001127:Arginine Vasopressin; D000584:Amiloride; D012964:Sodium; D011188:Potassium; D002118:Calcium