EXCITATORY EFFECT OF A NEW POLYPEPTIDE (ANTHOPLEURIN‐B) FROM SEA ANEMONE ON THE GUINEA‐PIG VAS DEFERENS

Abstract

1 Anthopleurin-B (AP-B, > 3 × 10⁻⁹ m), a newly isolated polypeptide from sea anemone (Anthopleura xanthogrammica), caused powerful rhythmic contractions in the guinea-pig isolated vas deferens. The other polypeptides anthopleurin-A from A. xanthogrammica and anthopleurin-C from A. elegantissima, elicited similar effects but in higher concentrations (> 5 × 10⁻⁸ m). Toxin II (10⁻⁶ m) isolated from the sea anemone, Anemonia sulcata, had no effect 2 The rhythmic contractions induced by AP-B were inhibited by phentolamine, bretylium, guanethidine, reserpine, 6-hydroxydopamine, tetrodotoxin (TTX) and verapamil. Mecamylamine, atropine, methysergide, chlorpheniramine, and indomethacin had no effect 3 AP-B (10⁻⁸m ∼10⁻⁵m) caused a dose-dependent increase in the amount of endogenous noradrenaline (NA) released from the vas deferens. AP-B (10⁻⁵m) increased the amount of NA released to approximately 310 times (12 μ/g tissue) that of untreated tissues 4 The AP-B-induced release of N A was inhibited or abolished by TTX, verapamil, or incubation in Ca-free medium 5 These results suggest that the AP-B-induced rhythmic contraction of the vas deferens is mediated through the release of NA from adrenergic nerve endings; AP-B is one of the most potent substances in stimulating NA release from the vas deferens.