title: Effects of histamine and histamine receptor antagonists on ion transport in rabbit descending colon.
abstract: The effects of histamine on colonic ion transport were examined in in vitro preparations of rabbit descending colon. Serosal addition of histamine (10(-5) M) produced a transient increase in short-circuit current (Isc) and transepithelial conductance. The Isc response to histamine could be blocked by removing Cl from both bathing solutions, adding furosemide (10(-3) M) to the serosal bathing solution, adding indomethacin to the serosal and mucosal bathing solutions (10(-5) M), or removing Ca from the serosal bathing solution. In addition, the histamine-induced increase in Isc was inhibited in a dose-dependent manner by the H1-receptor antagonist diphenhydramine, with a maximal inhibition at 10(-4) M and a half-maximal inhibition at 3 X 10(-7) M. The H2-receptor antagonist cimetidine (10(-3) M) was without effect on the histamine response. Measurement of unidirectional Na, K, and Cl fluxes revealed that serosal addition of diphenhydramine (10(-3) M) reduced basal Isc due to a decrease in mucosal-to-serosal Na flux. Serosal addition of diphenhydramine (10(-3) M) also inhibited the increase in Isc produced by serosal addition of prostaglandin E1, 8-bromo-cAMP, cholera toxin, or the ionophore A23187. Measurement of unidirectional K and Cl fluxes revealed that prostaglandin E1 alone increased serosal-to-mucosal K and Cl fluxes and reduced the mucosal-to-serosal K flux, thereby increasing net K and Cl secretion. Serosal diphenhydramine (10(-3) M) abolished the changes in Cl fluxes produced by prostaglandin E1 and reduced the magnitude of the changes in K fluxes.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000502:physiology; D002712:Chlorides / Q000378:metabolism*; D003106:Colon / Q000378:metabolism*; D000242:Cyclic AMP / Q000502:physiology; D006632:Histamine / Q000494:pharmacology*; D006634:Histamine H1 Antagonists / Q000494:pharmacology*; D006635:Histamine H2 Antagonists / Q000494:pharmacology*; D066298:In Vitro Techniques; D011188:Potassium / Q000378:metabolism*; D011817:Rabbits; D012964:Sodium / Q000378:metabolism*; D013268:Stimulation, Chemical
chemical_list: D002712:Chlorides; D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D006632:Histamine; D012964:Sodium; D000242:Cyclic AMP; D011188:Potassium; D002118:Calcium