Studies on the longitudinal muscle of the anterior mesentric artery of the domestic fowl.

1. A simple, isolated preparation is described in which the activity of the longitudinal muscle of the anterior mesenteric artery of the domestic fowl is recorded isotonically.2. The longitudinal muscle of the anterior mesenteric artery exhibited tone and marked spontaneous activity. Maximal shortening of this muscle was equal to about 60% of its resting length.3. Acetylcholine in low concentrations produced powerful contractions of the muscle, whereas low concentrations of catecholamines produced relaxation by an action on beta-receptors; much larger concentrations of adrenaline or noradrenaline contracted the muscle. A pharmacological analysis of the responses to electrical stimulation and to agonist drugs indicated that the muscle was supplied by excitatory, cholinergic nerves and by inhibitory, adrenergic nerves.