The absence of cardiovascular and respiratory responses to changes in right ventricular pressure in anaesthetized dogs.

1. This study was undertaken to determine whether physiological changes in pressure localized to the right ventricle result in reflex cardiovascular or respiratory responses. 2. Right ventricular systolic pressure was changed using a preparation in which right atrial and carotid sinus pressures were held constant. The pulmonary and hence the systemic circulation were perfused at constant flow. Vascular resistance and respiratory activity were assessed from the systemic arterial pressure and the phrenic electroneurogram. 3. Changes in right ventricular systolic pressure did not result in any consistent changes in heart rate, systemic arterial blood pressure or phrenic nerve activity. 4. Expected responses occurred to changes in the stimuli to carotid baroreceptors and chemoreceptors, distension of pulmonary arterial baroreceptors, and injections of veratridine into the left ventricle and pulmonary circulation. This suggests that the absence of responses to right ventricular distension was unlikely to have been due to damage to nervous pathways. 5. These results indicate that it is unlikely that there are reflexes arising from the right ventricle which have a major role in cardiovascular or respiratory control.