H₂Receptor-Mediated Relaxation of Circular Smooth Muscle in Human Gastric Corpus: the Role of Nitric Oxide (NO)

Abstract

This study was designed to examine the effects of histamine on gastric motility and its specific receptor in the circular smooth muscle of the human gastric corpus. Histamine mainly produced tonic relaxation in a concentration-dependent and reversible manner, although histamine enhanced contractility in a minor portion of tissues tested. Histamine-induced tonic relaxation was nerve-insensitive because pretreatment with nerve blockers cocktail (NBC) did not inhibit relaxation. Additionally, K+ channel blockers, such as tetraethylammonium (TEA), apamin (APA), and glibenclamide (Glib), had no effect. However, NG-nitro-L-arginine methyl ester (L-NAME) and 1H-(1,2,4)oxadiazolo (4,3-A) quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase (sGC), did inhibit histamine-induced tonic relaxation. In particular, histamine-induced tonic relaxation was converted to tonic contraction by pretreatment with L-NAME. Ranitidine, the H2 receptor blocker, inhibited histamine-induced tonic relaxation. These findings suggest that histamine produced relaxation in circular smooth muscle of human gastric smooth muscle through H2 receptor and NO/sGC pathways.

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“…Other reports have suggested similar enhancing effects of ginger extract on rabbit uterine smooth muscle tone and its spontaneous contractions [6]. In general, VDCC L is essential for the regulation of smooth muscle contractility in many species [7][8][9][10]. Nifedipine, a VDCC L blocker, can also block oxytocin (OXT)-induced phasic contraction in murine myometrium (unpublished data).…”

Acotiamide improves stress‐induced impaired gastric accommodation

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Physiological function and molecular composition of ATP-sensitive K⁺ channels in human gastric smooth muscle

“…Written informed consent was obtained from all patients who donated their gastric tissue. Human gastric tissues from the greater curvature (tissue samples from corpus and/or antrum) were obtained from 243 patients who underwent gastrectomies between 2011 and 2020 (10,11,(18)(19)(20)(21). Specimens of macroscopically normal tissue in the neoplastic areas were removed immediately after the surgical resection of the stomach.…”