On the effect of the frog's cardiac nerves on the resting current of the ob-moved ventricle

If you irritate the motor nerve, which carries excitation to a locally damaged skeletal muscle, then, as is known, its resting current decreases; a negative oscillation of the resting current occurs. The situation is different when the inhibitory nerve of the heart is irritated. In this case, Gaskell received an increase in the quiescent current. His classic experiment was conducted on the atria of the turtle heart, which are in a state of prolonged arrest. The latter circumstance is very important, since by itself stopping 1) or even slowing down the rhythm of cardiac contractions already changes the magnitude of the resting current. Gaskell achieved a prolonged stop of the atria by making an incision between the sinus and the atria, while sparing the connective tissue cord that runs along the posterior surface of the heart and contains the cardiac branch of the vagus nerve among the vessels. Thus, the atria, deprived of the sinus pulse, naturally retain a connection with the vagus nerves. If now the tip of the atria is damaged and the vagus nerve is torn apart, then the resting current increases. Gotch could not confirm Gaskell's observations, which, according to Bourdon Sanderson, depended on the low sensitivity of the capillary electrometer used by Gotch in his experiments. Soon after the string galvanometer was introduced into the physiological methodology, a number of authors (Meck U. Eyste, Samoylov2) together with Sergeyev) examined in more detail the oscillation of the resting current on the turtle's heart, I fully confirmed, at least from the factual side, everything that was described by Gaskel Ten at the time, the work of Einthoven and Rademake on this issue has recently appeared. These authors come to the conclusion that when the vagus nerve is irritated, the increase in the resting current depends solely on the contraction of the lungs, which, dragging the suspended atria with them, stretch them; stretching of the heart muscle, as well as stretching of muscle tissue in general, gives an increase in the resting current. This work forced A. F. Samoilov to return once again to the Gaskelian phenomenon. In 1917 A. F. Samoilov confirmed the existence of the contractile capacity of the turtle lungs under the influence of the vagus nerve; in fact, the lever connected to the lungs rises upwards in response to the irritation of the vagus nerve, but it is absolutely clear from the curves given that there is no parallelism between this movement of the lever and the deviation of the galvanometer string caused by the oscillation of the atrial resting current. The contraction of the lung may distort the picture of the Gaskell phenomenon, but the existence of the latter, as it appears from the cited work, is beyond any doubt. The experience put forward by A. F. finally convinces us of this. Samoilov on a turtle heart isolated from the lungs with the preservation of both vagus nerves. This experience clearly shows "that Haskel at one time correctly observed and correctly concluded: the vagus nerve, when it is decompressed, causes such a change in the heart muscle of the resting atrium of the turtle, which is accompanied by an increase in the initial electric current of rest"4).