Histamine receptors; responses and modulations towards agonist and antagonist on the rabbit ileum, in vitro study

ABSTRACT

This research work deals with the mechanism of action involved in determining the therapeutic potential of histamine and its blockers in gastrointestinal motility. Rabbits of equal weights were used in this study. They were brought from the animal house of BMSI, sacrificed in the Pharmacology Research laboratory. lleum strip were isolated and with special recommended methodology, longitudinal and circular muscles were separated. Individual muscle strip were then exposed separately to the desired drugs in the organ bath and reading were recorded on the polygraph machine. Basic Medical Sciences Institute, Jinnah Postgraduate Medical Centre, Karachi. 1996 to 1998. Histamine increases the contractile effects of longitudinal and circular muscle. H[1] and H[2] blockers potentiate its effects on longitudinal muscle while in circular muscle no change was observed with H[1] blocker whereas H[2] blocker antagonized the histaminic effects. However when H[1] blocker applied directly it increases the amplitude of contraction in longitudinal and circular muscle whereas H[2] blocker decreases the height of contractions. Histamine in the presence of H[1] and H[2] blocker augmented their effects in longitudinal muscle and antagonizes in circular layer. Gastrointestinal motility can be controlled through histamine and its antagonist. New drugs can be formulated on the basis of this study for the regulation of intestinal motility