Analysis of the effect of adrenergic agonists on longitudinal and circular smooth muscle of the terminal ileum of the guinea pig.

On the isolated longitudinal smooth muscle of the guinea pig's terminal ileum, in the presence of naphazoline, synephrine, pholedrine and ephedrine showing no adrenergic agonist activity, the dose-response curves of adrenaline and noradrenaline was found to be shifted to the right. Metanephrine, normetanephrine, and 3-methoxy-4-hydroxyphenylethylamine exhibited no alpha adrenergic agonist activity. On the circular smooth muscle of the terminal ileum the alpha adrenergic agonists studied elicited the same responses as on the longitudinal smooth muscle.