Pilot canine investigation of the cardiopulmonary baroreflex control of ventricular contractility

We performed a pilot investigation of the cardiopulmonary baroreflex control of ventricular contractility in two conscious dogs. We specifically measured spontaneous beat-to-beat hemodynamic variability before and after the administration of propranolol. We then identified the transfer function relating beat-to-beat fluctuations in central venous pressure (CVP) to maximal ventricular elastance (E
_max
) to characterize the cardiopulmonary baroreflex control of ventricular contractility, while accounting for the influences of arterial blood pressure fluctuations on E
_max
via the arterial baroreflex and heart rate fluctuations on E
_max
via the force-frequency relation. Our major finding is that the cardiopulmonary baroreflex responds to an increase (decrease) in CVP by increasing (decreasing) E
_max
via the beta-sympathetic nervous system.