title: Calcium oscillations index the extent of calcium loading and predict functional recovery during reperfusion in rat myocardium.
abstract: Delayed recovery of contractile function after myocardial ischemia may be due to prolonged recovery of high-energy phosphates, persistent acidosis, increased inorganic phosphate, and/or calcium loading. To examine these potential mechanisms, metabolic parameters measured by 31P nuclear magnetic resonance spectroscopy, and spontaneous diastolic myofilament motion caused by sarcoplasmic reticulum-myofilament calcium cycling indexed by the scattered light intensity fluctuations (SLIF) it produces in laser beam reflected from the heart, were studied in isolated atrioventricularly blocked rat hearts (n = 10) after 65 min of ischemia at 30 degrees C. All metabolic parameters recovered to their full extent 5 min after reperfusion. Developed pressure evidenced a small recovery but then fell abruptly. This was accompanied by an increase in end diastolic pressure to 37 +/- 5 mm Hg and a fourfold increase in SLIF, to 252 +/- 58% of baseline. In another series of hearts initial reperfusion with calcium of 0.08 mM prevented the SLIF rise and resulted in improved developed pressure (74 +/- 3% vs. 39 +/- 13% of control), and lower cell calcium (5.9 +/- 3 vs. 10.3 +/- 1.4 mumol/g dry wt). Thus, during reperfusion, delayed contractile recovery is not associated with delayed recovery of pH, inorganic phosphate, or high-energy phosphates and can be attributed, in part, to an adverse effect of calcium loading which can be indexed by increased SLIF occurring at that time.
authors.affiliation: Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore, Maryland 21224.
authors.forename: R G
authors.initials: RG
authors.lastname: Weiss
authors.forename: G
authors.initials: G
authors.lastname: Gerstenblith
authors.forename: E G
authors.initials: EG
authors.lastname: Lakatta
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003327:Coronary Disease / Q000378:metabolism; D003971:Diastole; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009200:Myocardial Contraction; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D010725:Phosphocreatine; D000255:Adenosine Triphosphate; D002118:Calcium