抄録
The aim of this study was to examine how cardiac gene transfer of sarcoplasmic reticulum calcium-ATPase (SERCA2a) can influence left ventricular (LV) mechanoenergetics in normal rats. Wistar rats were randomized to receive an adenovirus carrying either SERCA2a or β-galactosidase (βgal), or saline by a catheter-based technique. LV mechanical and energetics was analyzed in cross-circulated heart preparations 2-3 days after the infection. "SERCA2a" group showed the upward-shifted end-systolic pressure-volume relation, higher end-systolic pressure at 0.1 ml of intraballoon water and higher equivalent maximal elastance, i.e., the enhanced LV contractility, compared with "Normal", "βgal" and "Saline" groups. Moreover, faster LV relaxation rate was found in "SERCA2a" group. There was no significant difference in relation between myocardial oxygen consumption per beat and systolic pressure-volume area among all groups. Finally, oxygen cost of LV contractility in "SERCA2a" group was decreased to subnormal levels, but in "βgal" and "Saline" groups it remained unchanged. This lowered oxygen cost of LV contractility in "SERCA2a" hearts indicates energy saving in calcium handling during excitation-contraction coupling. Thus, the overexpression of SERCA2a was capable of transforming the normal energy utilization into a more efficient state in calcium handling, and super-inducing the supranormal contraction/relaxation due to the enhanced calcium handling. [J Physiol Sci. 2008;58 Suppl:S185]
