Restoration of Chronotropic Effects of Vagus Stimulation on Isolated Perfused Heart of the Guinea Pig

Abstract
As a result of observations on 50 isolated perfused hearts of guinea pigs it was found that the vagus nerves were active in 48 instances and the average duration of response to stimulation was 108 minutes. In one heart the vagi remained responsive to stimulation for 6 hours. It has again been shown that injections of appropriate doses of l-epinephrine are capable of restoring the unresponsive or exhausted vagal nerves to renewed chronotropic effectiveness.