THE EFFECT OF ADRENALIN ON THE AURICLE OF ELASMOBRANCH FISHES

Abstract

The elasmobranch fishes used were 3 spp. of skate, Raia erinacea, R. diaphanes, R. scabrata, and the dogfish, Squalus acanthias. Epinephrine chloride, 1 in 50,000 to 1 in 25,000, produces slowing or temporary complete inhibition of the beat of an isolated sinus-auricle preparation. The amplitude of beat may also decrease but both rate and amplitude recover, the latter frequently becoming temporarily greater than the original. Chloretone, in quantities equivalent to the amount present in epinephrine chloride of the concentrations used, was ineffective. The inhibitory effect of epinephrine on the elasmobranch auricle is interpreted as the response of an unbalanced parasympathetic mechanism in a heart which lacks a sympathetic accelerator innervation. An inhibitory emergency theory is suggested.