Pulmonary and systemic blood pressure response to serotonin: role of chemoreceptors

¹ Cardiovascular Unit and Department of Medicine "B", Hadassah University Hospital, and Hebrew University-Hadassah Medical School, Jerusalem, Israel

Large doses of serotonin (200 µg/ kg) in the anesthetized open-chest dog, administered into the femoral vein, right heart, pulmonary artery, left heart, ascending aorta or common carotid arteries, caused a marked pressor response in the systemic circulation. The latent period became shorter with the shift of the site of the injection toward the ascending aorta. After injection into the descending aorta a "double peak" pressor response was obtained. These observations, together with the demonstration of a much less pronounced pressor effect after elimination of the aortic and carotid chemoreceptors, indicate participation of chemoreceptor stimulation in the systemic pressor response. In the pulmonary artery the pressure rose markedly and consistently. A rise in the pulmonary venous pressure without any significant change in the left atrial pressure was observed, indicating pulmonary venous constriction. Chemoreceptor stimulation was shown to play a part also in the rise of both the pulmonary arterial and pulmonary venous pressures.