title: Dihydroxy bile salt-induced secretion of rubidium ion across the rabbit distal colon.
abstract: Possible mechanisms of dihydroxy bile salt-induced K+ secretion by the mammalian colon were evaluated by studying the effects of taurochenodeoxycholate (TCDC) on 86Rb+ transport across the isolated, short-circuited rabbit distal colon. Simultaneous measurements of 86Rb+ and 42K+ unidirectional fluxes were highly correlated [r = 0.964 for serosal (s) to mucosal (m) and 0.765 for m to s], indicating that Rb+ is a suitable tracer for K+ transport across the colon. Furthermore, mucosal Ba2+ (4 mM) or serosal ouabain (0.1 mM) decreased serosal to mucosal rubidium flux (JRbs----m) (from 0.24 +/- 0.02 to 0.09 +/- 0.02, and 0.08 +/- 0.01 mu eq X h-1 X cm-2, respectively) without affecting JRbm----s. Dibutyryl cyclic adenosine monophosphate (dBcAMP, 0.5 mM serosal) specifically increased JRbs----m of controls (from 0.21 +/- 0.05 to 0.67 +/- 0.09 mu eq X h-1 X cm-2) through a barium- (4 mM, mucosal) sensitive pathway without affecting JRbs----m. Mucosal addition of 2 mM TCDC increased tissue conductance (GT), reduced short-circuit (Isc) slightly, and reversed JRbnet (from 0.13 +/- 0.05 to -0.29 +/- 0.08 mu eq X h-1 X cm-2) principally by increasing JRbs----m. The TCDC-induced increases in JRbs----m were reduced by 0.1 mM serosal ouabain (from 0.53 +/- 0.03 to 0.11 +/- 0.02 mu eq X h-1 X cm-2) or 4 mM mucosal Ba2+ (from 0.76 +/- 0.07 to 0.32 +/- 0.04 mu eq X h-1 X cm-2).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001464:Barium / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology; D002635:Chenodeoxycholic Acid / Q000031:analogs & derivatives*; D003106:Colon / Q000378:metabolism*; D004553:Electric Conductivity; D006880:Hydroxy Acids / Q000494:pharmacology; D066298:In Vitro Techniques; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D011817:Rabbits; D012413:Rubidium / Q000378:metabolism*; D013655:Taurochenodeoxycholic Acid / Q000494:pharmacology*; D014268:Trifluoperazine / Q000494:pharmacology
chemical_list: D006880:Hydroxy Acids; D002635:Chenodeoxycholic Acid; D014268:Trifluoperazine; D001464:Barium; D013655:Taurochenodeoxycholic Acid; D010042:Ouabain; D003994:Bucladesine; D012413:Rubidium; D011188:Potassium