The effect of stimulation of the vagus nerves upon the development of rigor mortis of the mammalian heart

Stimulation of motor nerves hastens the onset of rigor mortis in the corresponding skeletal muscles. Cutting the nerves retards it, the retardation being due, it is believed, to the elimination of subminimal nerve impulses. Would the retardation of the rigor be still greater if inhibitory nerves could be stimulated? This question is not applicable to skeletal muscles, but it is a definite problem with reference to the onset of rigor in the heart muscle. Would a prolonged effective stimulation of the vagus nerves retard the onset of cardiac rigor? There were reasons to expect that the effect of such a stimulation would be indeed a retardation. The action of the cardiac vagus is inhibitory and the reverse of the action of a motor nerve; we might then expect that the effect of its stimulation upon cardiac rigor would also be the reverse of the effect of stimulation of a motor nerve upon the skeletal muscles, that is, retardation instead of hastening. Furthermore, increased muscular activity hastens the onset of rigor; it seemed reasonable to anticipate that the diminished activity, such as frequent standstill or slowing of the heart, would retard the onset of its rigor.

We have studied this question in 42 dogs, 16 cats and 10 rabbits. Both vagi were stimulated for half an hour before death and frequently also after death. Death was caused uniformly by bleeding and opening of the thorax. The outcome was a surprise; the obtained results were just the reverse of what was expected. But the results were uniform and unmistakable, We shall state them very briefly. They are as follows :

In all animals in which the vagi were stimulated, left and right ventricles stopped beating after death sooner than in the controls. The interval between the time of death and the beginning of the rigor in the left as well as in the right ventricle is in the experimented animals shorter than in the controls.