抄録
Hemodynamic effects of propranolol (0.5mg./Kg.) and subsequent carotid occlusion were investigated in 12 pentobarbital anesthetized intact dogs, including the measurement of both ventricular volumes by thermodilution method. The role of β-sympathetic nerve during pentobarbital anesthesia is remarkable judging from the changes induced by propranolol; that is, decreased cardiac output (3.69 to 2.87L./min.) and heart rate (186.6 to 138.7beats/min.), and increased left ventricular end-diastolic volume (3.28 to 4.03ml./Kg.) and end-diastolic pressure (4.0 to 10.9 mm.Hg) without increase of left ventricular stroke work, reflecting the negative inotropism of the drug. Subsequent carotid occlusion increased heart rate and myocardial contractility with the considerable vasoconstriction, that is, normalized mean circumferential shortening rate as a velocity of contraction of muscle fiber, and end-diastolic volume as a ventricular preload did not change while ventricular peak force as an afterload increased. The author concludes that the inotropic effect of carotid occlusion is mediated by so-called homeometric regulation together with β-sympathetic nerve activity.
