THE EFFECT OF DOPAMINE ON HUMAN GASTRIC SMOOTH MUSCLE

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Abstract
Dopamine had inhibitory effects on contractions of human gastric smooth muscle strips. Inhibition of spontaneous contractions occurred at high concentrations only, the mean maximum inhibition being 17% at a concentration of 47 10-4 M. It was unaffected by haloperidol (10-5 M) or textrodotoxin (10-6 M) but was abolished by a combination of phenoxybenzamine (10-5 M) and propranolol (10-5 M). Isoprenaline caused a dose-dependent inhibition of spontaneous contractions with mean maximal inhibition at a concentration of 46 10-6 M. These results suggest that there are no specific dopamine receptors in human gastric smooth muscle and that dopamine-induced inhibitory effects are due to stimulation of adrenergic receptors.