The isolated expansor secundariorum—a smooth muscle preparation from the wing of the domestic fowl

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Abstract
Some aspects of the pharmacology of an isolated smooth muscle, the expansor secundariorum, of the domestic fowl have been investigated. Adrenaline, isoprenaline, tyramine and 5-hydroxytryptamine caused the muscle to contract. The responses to adrenaline and noradrenaline were blocked by phentolamine but not by propranolol at a concentration of 1·7 × 10−4M. Tyramine was without effect on the muscle of reserpine treated birds. Cocaine potentiated the effect of noradrenaline but blocked the effects of tyramine. Acetylcholine and histamine had no effect and did not alter the responses of the muscle to noradrenaline. The response to noradrenaline was greater at temperatures below 23° and less at 38°. The muscle contracted rapidly on the addition of Tyrode cooled to 18°. It is concluded that the muscle is wholly innervated by adrenergic postganglionic fibres.