SEROTONIN-INDUCED SHORT-CIRCUIT CURRENT IN PIG JEJUNUM

This paper presents the effects of serotonin (5-HT) on short-circuit c urrent (SCC), sodium and chloride fluxes, and prostaglandin E2 release in pig jejunum, using the Ussing-chamber technique. 5-HT elicited a d ose-dependent increase in SCC, yielding an EC50 of 6 +/- 4 muM and E(M AX) of 77+/- 8 muA . cm-1 using about 100 muM. Inhibited sodium absorp tion and stimulated chloride secretion carried part of the 5-HT-induce d SCC. 5-HT caused a dose-independent PGE2 release, and indomethacin r educed the SCC-inducing effect of 5-HT by 40 %. Octreotide, a long-las ting somatostatin analogue, also reduced 5-HT-induced SCC by about 40 %, while tetrodotoxin (TTX) did not alter the effect of 5-HT. In concl usion, 5-HT causes a dose-dependent indomethacin and octreotide-sensit ive, and TTX-insensitive increase in SCC, and a chloride secretion and inhibited sodium absorption and an increased release of PGE2 in pig j ejunum in vitro.