title: Magnesium ion is beneficial in hypothermic crystalloid cardioplegia.
abstract: The role of magnesium ion and its relation to the calcium concentration of cardioplegic solutions was reexamined in this study. Isolated rat hearts were used with an oxygenated modified Krebs-Henseleit bicarbonate buffer as perfusion medium. The hearts were arrested for 20 minutes at 37 degrees C or 90 minutes at 24 degrees C. Treatment groups received one dose of nine possible cardioplegic solutions containing magnesium (0, 1.2, or 15 mmol/L) and calcium (0.05, 1.5, or 4.5 mmol/L). Ninety-six percent of the 75 magnesium-treated hearts recovered, regardless of the calcium concentration, in contrast to a 52% recovery rate in the 69 hearts that did not receive magnesium. The addition of 15 mmol/L Mg2+ to a cardioplegic solution containing no magnesium but 0.05 mmol/L Ca2+ significantly increased (p less than 0.01) the percent recovery of the following parameters of cardiac function: systolic pressure, 74% to 93% (37 degrees C), 64% to 98% (24 degrees C); cardiac output, 76% to 101% (37 degrees C), 71% to 102% (24 degrees C); stroke work, 64% to 104% (37 degrees C), 52% to 99% (24 degrees C); and adenosine triphosphate level, 75% to 83% (37 degrees C), 58% to 90% (24 degrees C). There were significant reductions (p less than 0.03) in percent recovery (37 degrees C and 24 degrees C) of cardiac output, stroke work, and adenosine triphosphate level in the groups that contained 0 or 15 mmol/L Mg2+ as the calcium concentration was increased from 0.05 to 4.5 mmol/L.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Surgery Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: P S
authors.initials: PS
authors.lastname: Brown
authors.forename: F W
authors.initials: FW
authors.lastname: Holland
authors.forename: G L
authors.initials: GL
authors.lastname: Parenteau
authors.forename: R E
authors.initials: RE
authors.lastname: Clark
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002314:Cardioplegic Solutions / Q000493:pharmacokinetics / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006321:Heart / Q000187:drug effects*; D006324:Heart Arrest, Induced / Q000379:methods*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007036:Hypothermia, Induced; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D002314:Cardioplegic Solutions; D000255:Adenosine Triphosphate; D008274:Magnesium; D002118:Calcium