Oxygen receptors in the rainbow trout, <i>Salmo gairdneri</i>

Abstract

A new technique for the detection in situ of oxygen-sensitive chemoreceptors in fish is described. By studying the hypoxic responses of the rainbow trout, Salmo gairdneri, at least two loci of respiratory control were found to be operating. One component initiated the hypoxic bradycardia and its rapid release, a second was responsible for ventilatory responses. The anterodorsal region of the first branchial arches has been established as a peripheral oxygen-sensitive chemoreceptor site, mediating bradycardia, without affecting either the amplitude or frequency of breathing. The study does not preclude the existence of oxygen receptors in other areas of the fish.