Time related Characteristics of cardiac systole, diastole, baroreeeptor activity and inactivity during vagal stimulation and mild haemorrhage in the dog

Abstract

The duration of cardiac systole and diastole in each individual cardiac cycle were measured from aortic pressure curves during vagal stimulation and mild haemorrhage with simultaneous recording of aortic baroreceptor single fibre nerve activity. The duration of cardiac diastole was highly correlated with the duration of cardiac cycle in all the interventions. The correlation coefficient between the duration of cardiac systole and the duration of cardiac cycle was not as high as that between the duration of cardiac cycle and cardiac diastole. A highly linear correlation also existed between the duration of cardiac cycle and the duration of baroreceptor inactivity time. The same was true when the duration of baroreceptor inactivity time was compared with the duration of cardiac diastole. It is concluded that the duration of baroreceptor inactivity time may inform the central nervous system about heart rate.