Abstract
SummaryObservations have been made on the effects of nerve stimulation and drugs on an isolated perfused segment of the central artery of the rabbit ear.Stimulation applied transmurally, peri‐arterially or to the ventral auricular nerve caused vascoconstriction.The vascoconstrictor response to peri‐arterial stimulation was due to excitation of nerve fibres arising from the superior cervical ganglion. The response was enhanced after cocaine, and abolished or greatly reduced after guanethidine, procaine and dibenyline.Noradrenaline produced vascoconstrictor responses which were enhanced after ganglionectomy and after cocaine, and abolished by dibenyline.Acetyl choline caused dilatation, but only when the tone of the artery was raised by sympathetic stimulation. The effect of acetyl choline was greatly reduced after atropine.Histamine caused vasoconstriction which was abolished after mepyramine.5‐hydroxytryptamine had only weak vasoconstrictor activity, but it markedly potentiated the action of noradrenaline and sympathetic nerve stimulation.Angiotensin has weak vasoconstrictor activity.
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