Summary

The purpose of this research was to obtain experimental data, which would allow to develop an electronic model of the regulation of the heart function (heart rate) by the two antagonistically acting components of the autonomic nervous system, i.e. the sympathetic and parasympathetic systems and to construct an electronic analogue simulator of the sympathetic and parasympathetic nervous control of the intrinsic cardiac pacemaker.

Acute experiments were performed on anesthetized open-chest dogs in which the right stellate (sympathetic) and right vagus (parasympathetic) cardiac nerves were stimulated, individually or simultaneously with varying constant pulse amplitude (15v) and duration (1 msec), rectangular and  rates varying from 1 p.p.s. to 40 p.p.s, for a constant duration of 6.3 sec. Several parameters of the cardiac function were recorded. Heart R-R periods were monitored and are presented below in a form of graphs describing the heart rate response to nerve stimulation. The response to parasympathetic stimulation was more immediate and markedly more pronounced initially but short lasting in comparison with the response to sympathetic stimulation, which was somewhat delayed, of lesser intensity but lasted much longer. In combined stimulation, the vagal response was markedly depressed and the sympathetic response was practically unchanged in comparison to the isolated sympathetic stimulation.

The electronic analogue simulator of the autonomic heart rate control was successfully developed on the basis of the experimental studies, it allowed to simulate these functions in adequate fashion. It should be useful in further studies on the autonomic nervous control of the intrinsic cardiac pacemaker and in more complete understanding of the mechanisms involved.

Publications:

1. An analoque of the nervous control of intrinsic cardiac pacemaker. J.K. Cywinski, A.C.K. Kutty, W.J. Wajszczuk. Proceedings - 8th ICMBE - Palmer House, Chicago, IL; July 20-25, 1969; Session 20-5, Wednesday, July 23, 1969 - Modeling, Cardiovascular System.

2. Autonomic Nervous Control of the Intrinsic Cardiac Pacemaker and its electronic Analogue simulator. J.K. Cywinski, W.J. Wajszczuk, A.C.K. Kutty. In The nervous system and electric currents, vol. 2, Edited by Norman L. Wulfsohn and Anthony Sances, Jr.; Plenum Press, 1971, pp. 35-45