Kybernetics of cardio-respiratory synchrony: characterization by modulating cardiac frequency

The work concerns the special and particularly efficient kybernetic system which synchronizes respiratory and cardiac activities in rabbits. An experimental procedure is worked out to characterize its potentialities. It consists of an artificial, elective and continuous slowing down of cardiac frequency in left-side vagotomized animals. Whenever synchrony happens to exist - and this can be provided - such slowing down will tend to throw the two rhythms out of phase. The stronger the kybernetic system, then the more it should be able to outweigh such disturbing tendencies. The correlation between the speed of cardiac slowing and the number of synchronized breaths resisting such disturbances follows a hyperbolic course. Characteristics of this hyperbola offer a useful means of quantifying the kybernetic system.