Rapid adaptation of myocardial calcium homeostasis to short episodes of ischemia in isolated rat hearts

• Published in: The American heart journal Vol. 131; no. 6; pp. 1106 - 1112
• Main Authors: Smith, Geoffrey B., Stefenelli, Thomas, Wu, Shao T., Wikman-Coffelt, Joan, Parmley, William W., Zaugg, Christian E.
• Format: Journal Article
• Language: English
• Published: New York, NY Mosby, Inc 01.06.1996; Elsevier
• Subjects: Adaptation, Physiological; Animals; Biological and medical sciences; Calcium - metabolism; Cardiology. Vascular system; Coronary heart disease; Heart; Homeostasis; Medical sciences; Myocardial Ischemia - metabolism; Myocardial Ischemia - physiopathology; Myocardial Reperfusion; Myocardium - metabolism; Rats; Sodium - metabolism; Systole; Time Factors; Ventricular Pressure; Vertebrata; Mammalia; Calcium; Ischemia; Rat; Rodentia; Homeostasis; Cardiovascular disease; Exploration; Isolated organ
• ISSN: 0002-8703; 1097-6744
• DOI: 10.1016/S0002-8703(96)90084-8

Short episodes of ischemia and reperfusion (ischemic preconditioning) have been shown to attenaute the detrimental rise in intracellular free Ca 2+ ([Ca 2+] i) caused by subsequent sustained ischemia. The purpose of this study was to investigate the detailed time course of [Ca 2+] i during such short episodes of ischemia and reperfusion. [Ca 2+] i was measured at a high time resolution by surface fluorometry and indo-1 in isolated perfused rat hearts during three episodes of 5 minutes of ischemia followed by 5 minutes of reperfusion. We found that the rise in systolic [Ca 2+] i was significantly smaller during the second (191% ± 67%) and third (194% ± 75%) episodes of ischemia than during the first episode (289% ± 75%, P < 0.05 vs both subsequent episodes). This attenuated rise in systolic [Ca 2+] i was preserved during perfusion with low extracellular Na + (105.5 mmol/L [Na +] o). During short episodes of ischemia and reperfusion, [Ca 2+] i rises less during the second and third ischemic episode than during the first episode. Thus one transient ischemic stimulus led to a rapid adaptation of [Ca 2+] i homeostasis to subsequent ischemic conditions. Such a rapid adaptation might be an important mechanism of the ischemic preconditioning phenomenon in protecting against ischemic injury.