Histamine receptors in the guinea pig ileum

Abstract

Histamine and some related compounds acting selectively on H2-or H1 receptors were tested for their ability to contract the guinea pig ileum, in the usual whole ileum preparation and in the longitudinal muscle preparation. The concentrations elicited by histamine in both kinds of preparations were not potentiated by cimetidine or metiamide and were not inhibited by administration of H2 receptor selective agonists in doses which were subthreshold for contracting the guinea pig ileum; higher doses of the H2 agonists could actually potentiate the effect of histamine. The results obtained suggest that H2 receptors with relaxing effect do not occur in the guinea pig ileum or at least that they are not involved in the contraction of the longitudinal muscle layers. The possibility that a sub-type of H2 receptors with properties different from those of the "classical" H2 receptors so far known, exists in the guinea pig ileum, cannot be excluded.

A controlled study to investigate anti-diarrhoeal effect of the stem-bark fractions of Terminalia avicennioides in laboratory animal models

“…Histidine is converted to histamine by a specific enzyme, histidine decarboxylase. Histamine is known to contract several types of smooth muscle, including those of the bronchi, gut and large blood vessels [26] . Histamine-induced contraction of the smooth muscle of guinea pig ileum is mediated by H 1 receptors found throughout the gastrointestinal tract.…”

Effects of histamine, high potassium and carbachol on 42K efflux from longitudinal muscle of guinea‐pig intestine

“…4). It has been reported that H2 receptors can be demonstrated in the ileal strip preparation (Ambache & Aboo Zar, 1970;Ambache, Killick & Aboo Zar, 1973;Bertaccini, Molina, Zappia & Zseli, 1979) and it was possible that activation of these was inhibiting 42K efflux in response to H1 activation. However, cimetidine (10-7-10-5 M), an H2 receptor blocker (Brimblecombe, Duncan, Durant, Emmett, Ganellin & Parsons, 1975) also did not increase…”

A‐80426, a potent α2‐adrenoceptor antagonist with serotonin uptake blocking activity and putative antidepressant‐like effects: I. Biochemical profile

“…For studies of a,-adrenoceptors, rabbit aortae (New7 Zealand White, Hazleton, Inc., Kalamazoo, MI) were employed, essentially as previously described [Hancock et al, 1995al. Antagonism of liistaminergic H, and niiiscarinic M, receptors in the isolated guinea pig ileurn (male, alhino Hartley, Charles Kiver, Inc., Portage, MI) against the contractile effects of histamine or carbachol, respec-tively, were performed as described [Bertaccini et al, 1979;arid Malta et al, 1982, respectively]. Data for antagonism expcrimcrits in isolated tissues were analyzed as clescribed [Schild, 19471. The effects of A-80426 or1 presyriaptic azadrcrioceptors controlling neurotransmitter release were further evaluated in rat atria (aZL3) arid rabbit pulmonary artery (azA) as described [ Connaughton and Docherty, 1990;and Endo et al, 1977, respectivcly].…”