Effect of captopril on oxyphenbutazone and ethanol-induced gastric lesions in rats.

We studied the effect of the angiotensin converting enzyme inhibitor, captopril, on two models of gastric ulcers; oxyphenbutazone and ethanol-induced lesions. There was a significant protective effect against oxyphenbutazone-induced ulcers, which was prevented by prior administration of indomethacin. Captopril, however, failed to protect against ethanol-induced lesions. These findings are discussed in the light of captopril being a sulfhydryl compound with prostaglandin-releasing activity.

Dual action of zinc on ileal smooth muscle--zinc-calcium interaction.

Effect of zinc sulphate was studied on histamine-induced contractions on guinea-pig ileum. In doses of 1.72 X 10(-7)M or less no effects were observed. Zinc sulphate in doses of 3.44 X 10(-7)M, 6.88 X 10(-7)M and 1.72 X 10(-6)M produced dual effect. Short exposure of tissue for 10 min to zinc sulphate resulted in significant dose dependent potentiation of histamine effect whereas after washing the tissue of zinc sulphate, histamine response was inhibited significantly and in a dose dependent manner. Higher concentrations of zinc sulphate of 3.44 X 10(-6)M and above produced irreversible inhibition of histamine response. The above observations have been explained in terms of zinc-calcium interaction. It is hypothesized that interaction of zinc with calcium may take place extracellularly at membrane level and intracellularly.

Probable mechanism of action of methyldopa on cholinergically innervated tissues.

Methyldopa (200 and 400 micrograms/ml) induced an increase in the responsiveness of guinea-pig ileum to ACh after incubation for 1 hr 15 min. However, no such effect was observed in the case of frog rectus abdominis muscle. It is suggested that methyldopa influences receptor mechanisms associated with cholinergic muscarinic but not nicotinic receptors.