The Journal of Physiological Sciences

, Volume 62, Issue 3, pp 221–231

Evaluation of left ventricular mechanical work and energetics of normal hearts in SERCA2a transgenic rats

  • Guo-Xing Zhang
  • Koji Obata
  • Daisuke Takeshita
  • Shinichi Mitsuyama
  • Tamiji Nakashima
  • Akio Kikuta
  • Masumi Hirabayashi
  • Koichi Tomita
  • Roland Vetter
  • Wolfgang H. Dillmann
  • Miyako Takaki
Original Paper

DOI: 10.1007/s12576-012-0200-4

Cite this article as:
Zhang, GX., Obata, K., Takeshita, D. et al. J Physiol Sci (2012) 62: 221. doi:10.1007/s12576-012-0200-4

Abstract

Cardiac sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA2a) is responsible for most of the Ca2+ removal during diastole and a larger Ca2+ handling energy consumer in excitation–contraction (E–C) coupling. To understand the cardiac performance under long-term SERCA2a overexpression conditions, we established SERCA2a transgenic (TG) Wistar rats to analyze cardiac mechanical work and energetics in normal hearts during pacing at 300 beats/min. SERCA2a protein expression was increased in TGI and TGII rats (F2 and F3 of the same father and different mothers). Mean left ventricular (LV) end-systolic pressure (ESP) and systolic pressure–volume area (PVA; a total mechanical energy per beat) at midrange LV volume (mLVV) were significantly larger in TGI rats and were unchanged in TGII rats, compared to those in non-TG [wildtype (WT)] littermates. Mean myocardial oxygen consumption per minute for E–C coupling was significantly increased, and the mean slope of myocardial oxygen consumption per beat (VO2)–PVA (systolic PVA) linear relation was smaller, but the overall O2 cost of LV contractility for Ca2+ is unchanged in all TG rats. Mean Ca2+ concentration exerting maximal ESPmLVV in TGII rats was significantly higher than that in WT rats. The Ca2+ overloading protocol did not elicit mitochondrial swelling in TGII rats. Tolerance to higher Ca2+ concentrations may support the possibility for enhanced SERCA2a activity in TGII rats. In conclusion, long-term SERCA2a overexpression enhanced or maintained LV mechanics, improved contractile efficiency under higher energy expenditure for Ca2+ handling, and improved Ca2+ tolerance, but it did not change the overall O2 cost of LV contractility for Ca2+ in normal hearts of TG rats.

Keywords

Pressure–volume areaSERCA2aTransgenic rat

Copyright information

© The Physiological Society of Japan and Springer 2012

Authors and Affiliations

  • Guo-Xing Zhang
    • 1
    • 2
  • Koji Obata
    • 1
  • Daisuke Takeshita
    • 1
  • Shinichi Mitsuyama
    • 1
  • Tamiji Nakashima
    • 3
  • Akio Kikuta
    • 3
  • Masumi Hirabayashi
    • 4
  • Koichi Tomita
    • 4
  • Roland Vetter
    • 5
  • Wolfgang H. Dillmann
    • 6
  • Miyako Takaki
    • 1
  1. 1.Department of Physiology IINara Medical University School of MedicineKashiharaJapan
  2. 2.Department of PhysiologyMedical College of Soochow UniversitySuzhouPeople’s Republic of China
  3. 3.Department of Anatomy, School of MedicineUniversity of Occupational and Environmental HealthKitakyushuJapan
  4. 4.National Institute for Physiological SciencesOkazakiJapan
  5. 5.Institut für Klinische Pharmakologie und ToxikologieCharité-Universitätsmedizin BerlinBerlinGermany
  6. 6.Department of MedicineUniversity of California, San DiegoLa JollaUSA