DISTRIBUTION OF VAGUS CONTROL OF THE TURTLE HEART

Abstract

The distribution of function of the right and left vagi was examined in 2 spp. of turtle [Pseudemys elegans and Clemmys marmorata]. The inotropic effect of either vagus on the auricles was greatest on the homo-lateral auricle. Vagal chronotropic effects could be separated from inotropic on the basis of stimulation thresholds, but a definite overlap existed. Dromotropic and chronotropic actions, however, could not be divided in the same manner. It was concluded, therefore, that no definite evidence could be brought forward against the concept that a common mechanism is mediated by the vagus fibers and that different effects produced are the result of the distribution of these fibers.