Loading sequence is a major determinant of afterload-dependent relaxation in intact canine heart

摘要: To elucidate the role of loading sequence in afterload-dependent slowed relaxation hearts situ, time constants (Texp from best exponential fitting method and TL semilogarithmic method) isovolumetric left ventricular (LV) pressure decay were studied nine anesthetized open-chest dogs under pharmacological blockade autonomic nerve activity. An afterload change was imposed by clamping ascending or descending aorta to make peak LV early late systole. During interventions, contractions with systole Texp significantly (P less than 0.05) larger those any comparable range. Moreover, both directly correlated 0.01) irrespective clamp mode aorta. In another protocol, marked differences also observed between each 25 pairs different but dimension (segment length). Thus situ could not be attributed an increased total load altered associated increase afterload.