Key result
Cardiopulmonary bypass and cold-blood cardioplegia increased myocardial Ca2+ load, doubled Ca2+ uptake (3.91 to 8.15 nM/s), and tripled Ca2+ release (0.90 to 2.73 nM/s) (p<0.05).
Why the study?
Does cardiopulmonary bypass and cold-blood cardioplegia alter myocardial Ca2+ cycling in patients undergoing coronary artery bypass grafting?
Observational (n=13)
Does cardiopulmonary bypass and cold-blood cardioplegia alter myocardial Ca2+ cycling in patients undergoing coronary artery bypass grafting?
Absolute Event Rate: 8.15% vs 3.91%
p-value: p=<0.05
Cardiopulmonary bypass and cold-blood cardioplegia significantly increase myocardial Ca2+ load, uptake, and release by the sarcoplasmic reticulum.
Altered Ca2+ cycling post-bypass may underlie dysfunction; hypothesis-generating for Ca2+-targeted strategies in CABG.
We studied myocardial Ca2+ cycling during cardiopulmonary bypass and cold-blood cardioplegia (CPB/CBC) in patients with coronary heart disease undergoing coronary artery bypass grafting. Right atrial biopsies were taken from 13 patients before and after CPB/CBC: after pericardiotomy, immediately after aortic cross-clamp removal, and following termination of CPB/CBC. Changes in ionized Ca2+ concentration (nM) were monitored with indo 1 during Ca2+ uptake and Ca2+ release by sarcoplasmic reticulum in a medium containing 1% homogenized myocardium. Ryanodine inhibition was used to estimate Ca2+ release channel activity. With CPB/CBC, the initial Ca2+ concentration of reaction media increased 33%, (962 +/- 150 to 1262 +/- 106 nM; mean +/- SD). Ca2+ cycling increased asymmetrically, 108% for Ca2+ uptake (3.91 +/- 1.32 to 8.15 +/- 3.17 nM/s), 197% for Ca2+ release (0.90 +/- 0.80 to 2.73 +/- 1.13 nM/s), and 68% for the ratio of Ca(2+)-release to Ca(2+)-uptake activities (0.22 +/- 0.14 to 0.37 +/- 0.13). The dissociation constant of the Ca2+ pump for Ca2+ was unaltered by CPB/CBC (289 +/- 76 nM). During the time period that was studied post-bypass, Ca(2+)-pump activity remained increased, although the Ca(2+)-channel activity returned to pre-bypass values (all p < 0.05). We conclude that CPB/CBC produces increased myocardial Ca2+ load, twofold increased Ca2+ uptake, and threefold increased Ca2+ release by sarcoplasmic reticulum.
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O’Brien et al. (1997) conducted an observational in Coronary heart disease (n=13). Cardiopulmonary bypass and cold-blood cardioplegia (CPB/CBC) vs. Pre-bypass baseline was evaluated on Ca2+ uptake by sarcoplasmic reticulum (nM/s) (p=<0.05). Cardiopulmonary bypass and cold-blood cardioplegia increased myocardial Ca2+ load, doubled Ca2+ uptake (3.91 to 8.15 nM/s), and tripled Ca2+ release (0.90 to 2.73 nM/s) (p<0.05).
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