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Updated: Apr 26, 2026
A Recovery Cardiopulmonary Bypass Model Without Transfusion or Inotropic Agents in Rats
Published on: March 23, 2018
Chronic intermittent hypobaric hypoxia ameliorates ischemia/reperfusion-induced calcium overload in heart via Na/Ca2+
Hui-Jie Ma1, Qian Li, Hui-Juan Ma
1Department of Physiology, Hebei Medical University, Shijiazhuang, China.
Background/Aims:
Chronic intermittent hypobaric hypoxia (CIHH) protects the heart against ischemia/reperfusion (I/R) injury. This study investigated the calcium homeostasis mechanism and the role of Na(+)/Ca(2+) exchanger (NCX) in the cardiac protective effect of CIHH in developing rats.
Methods:
Neonatal male rats received CIHH treatment or no treatment (control) in a hypobaric chamber simulating 3000-meter altitude for 42 days. The left ventricular function of isolated hearts was evaluated after 30 minutes of ischemia and 60 minutes of reperfusion. Myocardial infarct size, intracellular Ca(2+) concentration ([Ca(2+)]i), Na(+)-Ca(2+) exchanger currents (I(Na/Ca)) in ventricular myocytes, and NCX1 protein level in the sarcolemmal membrane were determined.
Results:
The recovery of cardiac function after I/R was improved, with the myocardial infarct size reduced, in CIHH rats compared with control rats (p<0.05). These effects were attenuated by Bay K8644, an L-type Ca(2+) channel agonist, or ryanodine, a sarcoplasmic reticulum Ca(2+) channel receptor activator. Furthermore, the increases in [Ca(2+)]i during I/R were blunted in CIHH rats, but this effect was abolished by Bay K8644 or chelerythrine, a protein kinase C (PKC) inhibitor. The I(Na/Ca) was decreased and the reversal potential of INa/Ca was shifted toward negative potential during simulated ischemia in the control cardiomyocytes (p<0.05). The inhibition of NCX1 protein expression during I/R was smaller in the CIHH rats than in the control rats (p<0.05).
Conclusion:
These data suggest that CIHH protects developing rat hearts during I/R by enhancing the resistance against calcium overload and by preserving normal I(Na/Ca) and NCX1 protein. PKC activation might be involved in this protective process of CIHH.
