Alterations in intracellular ionic calcium levels in isolated adult rat cardiac myocytes due to the generation of free radicals

Conference · Fri Mar 15 00:00:00 EST 1991 · FASEB Journal (Federation of American Societies for Experimental Biology); (United States)

OSTI ID:5238598

Burton, K P; Nazeran, H; Hagler, H K ^[1]

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1. Univ. of Texas, Dallas, TX (United States)

Oxygen-derived free radical production has been documented to occur on reperfusion of the ischemic myocardium. Intracellular ionic calcium ((Ca{sup ++}){sub i}) levels in isolated adult rat cardiac myocytes (M) exposed to free radicals were evaluated using the fluorescent calcium indicator, fura-2. The effect of different time periods of free radical exposure and the level of extracellular Ca{sup ++} concentration on altering (Ca{sup ++}){sub i} was examined. The free radical generating system (FRGS) utilized consisted of a HEPES buffered physiological salt solution containing 2.3 mM purine, 2.4. {mu}M iron-loaded transferrin and 0.01 U/ml xanthine oxidase. M maintained in HEPES buffer or the HEPES buffer containing purine and iron-loaded transferrin continued to stimulate, exhibited relatively uniform 340/380 ratios and maintained a rod shape for extended time periods. M continuously exposed to the FRGS showed a significant increase in (Ca{sup ++}){sub i}, became unresponsive to stimulation at 31 {plus minus} 7 (SE) min and eventually exhibited contracture. Exposure to the FRGS for 10 min resulted in a response similar to continuous exposure. M exposed to the FRGS for 5 min exhibited regular Ca{sup ++} transients for 55{plus minus}5 min. M exposed to the FRGS for 10 min and maintained in 2.5 mM Ca{sup ++} versus 1.25 mM Ca{sup ++}, accumulated significantly higher (CA{sup ++}){sub i}. Quiescent myocytes continuously exposed to the FRGS also exhibited a significant increase in (Ca{sup ++}){sub i} over time. Thus, a brief period of free radical exposure may induce subsequent damage. Alterations in Ca{sup ++} flux resulting from the generation of free radicals may possibly contribute to the development of Ca{sup ++} overload and myocardial arrhythmias.

• OSTI ID: 5238598
• Report Number(s): CONF-9104107-; CODEN: FAJOE
• Journal Information: FASEB Journal (Federation of American Societies for Experimental Biology); (United States), Vol. 5:5; Conference: 75. annual meeting of the Federation of American Societies for Experimental Biology (FASEB), Atlanta, GA (United States), 21-25 Apr 1991; ISSN 0892-6638
• Country of Publication: United States
• Language: English

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