Exposure to free radicals alters ionic calcium transients in isolated adult rat cardiac myocytes.
Oxygen-derived free radical production has been documented to occur on reperfusion of the ischemic myocardium. Intracellular ionic calcium ([Ca++]i) levels in isolated adult rat cardiac myocytes exposed to free radicals were evaluated using fura-2. The effect of different time periods of free radical exposure on altering [Ca++]i was examined. Myocytes were either exposed to the free radical generating system continuously or exposed for 5 or 10 minutes and then returned to the HEPES buffer. Myocytes maintained in HEPES buffer or the HEPES buffer containing purine and iron-loaded transferrin continued to stimulate, exhibited relatively uniform 340/380 nm ratios and maintained a rod shape. Continuous exposure to free radicals resulted in a significant increase in [Ca++]i. Myocytes became unresponsive to stimulation at 31 +/- 7 (SE) minutes and eventually exhibited contracture. Exposure to the free radical generating system for 10 minutes resulted in a response similar to continuous exposure. Myocytes exposed to the generating system for 5 minutes exhibited regular calcium transients for 55 +/- 5 minutes. Thus, even a brief period of free radical exposure alters calcium flux and may induce subsequent myocardial damage.
Burton
K P
KP
Department of Radiology, University of Texas Southwestern Medical Center, Dallas 75235-9071.
Hagler
H K
HK
Nazeran
H
H
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D002469:Cell Separation; D004558:Electric Stimulation; D004594:Electrophysiology; D006321:Heart / Q000187:drug effects*; D006352:Heart Ventricles; D007477:Ions; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D009994:Osmolar Concentration; D051381:Rats; D017382:Reactive Oxygen Species / Q000494:pharmacology*; D013997:Time Factors
D007477:Ions; D017382:Reactive Oxygen Species; D002118:Calcium