Baroreflex control of left ventricular contractility in the conscious dog

The hypothesis was tested that the carotid baroreflex exerts reflex control of left ventricular contractility in the conscious dog. Reversible vascular isolation of the carotid sinus regions in the conscious dog permitted control of baroreflex input. Left ventricular pressure and volume (measured using conductance catheter), mean arterial pressure (MAP), heart rate (HR), cardiac output (CO) and stroke volume (SV) were measured in response to changes in carotid sinus pressures. Left ventricular contractility was assessed using several indices including the slope of the end-systolic pressure volume relation (ESPVR), and the slope of the preload recruitable stroke work relationship (PRSWR). Decreases in carotid sinus pressure (CSP) consistently resulted in reflex increases in MAP, HR, SV, and the slope of both the ESPVR and PRSWR. The authors conclude that activation of the carotid baroreflex can enhance inotropic state in the conscious dog