Nigerian Journal of Physiological Sciences

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Influence of nitric oxide on histamine and carbachol – induced gastric acid secretion in the common African toad – Bufo regularis

ARA Alada, HM Salahdeen, OO Akande, GO Idolor


The study aimed to determine the influence of nitric oxide (NO) on the action of histamine and carbachol on acid secretion in the common African toad – Bufo regularis. Gastric acidity was determined by titration method. The acid secretion was determined when nitric oxide was absent following administration of NO synthase inhibitor; N-nitro-L-arginine methyl ester (L-NAME) and when nitric oxide was in excess by administration of exogenous NO donor, sodium nitroprusside (SNP). Histamine or carbachol increased acid secretion in the toad. Acid output increased from 0.32 ± 0.04 mEq/15min to 0.56 ± 0.08 and 0.61 ± 0.05 mEq/15min for histamine and carbachol respectively (P < 0.05). Pretreatment of the toad with L-NAME produced further increases in histamine (0.62 ± 0.06 mEq/15min) or carbachol (0.74 ± 0.06 mEq/15min) induced acid secretion respectively. SNP however, completely abolished the acid secretion stimulated by either histamine or carbachol. It was therefore concluded that nitric oxide has a negative influence on the histamine or carbachol – stimulated acid secretion in the toad – Bufo regularis.

Keywords: nitric oxide, histamine, carbachol, acid secretion

Nigerian Journal of Physiological Sciences Vol. 20(1&2) 2005: 74-78

AJOL African Journals Online