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THE JOURNAL OF CARDIOVASCULAR SURGERY
Rivista di Chirurgia Cardiaca, Vascolare e Toracica
Indexed/Abstracted in: BIOSIS Previews, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
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ORIGINAL ARTICLES CARDIAC SECTION
The Journal of Cardiovascular Surgery 2004 February;45(1):1-13
Comparison of hyperkalemic cardioplegia with altered [CaCl2] and [MgCl2] on [Ca2+]i transients and function after warm global ischemia in isolated hearts
Camara A. K. S. 1, Chen Q. 1, An J. 1, Novalija E. 1,2, Riess M. L. 1,2, Rhodes S. S. 1,5, Stowe D. F.1,2,3,4,5
1 Anesthesiology Research Laboratories Department of Anesthesiology Medical College of Wisconsin, Milwaukee, WI, USA
2 Department of Physiology Medical College of Wisconsin, Milwaukee, WI, USA
3 Cardiovascular Research Center Medical College of Wosconsin, Milwaukee, WI, USA
4 Research Service, Veterans Affairs Medical Center Milwaukee, WI, USA
5 Department of Biomedical Engineering, Marquette University, Milwaukee, WI, USA
Aim. [MgCl2] and [CaCl2] may modify the cardioprotective effects of hyperkalemic cardioplegia (CP). We changed [MgCl2] and [CaCl2] in a CP solution to examine their effects on [Ca2+]i transients and cardiac function before and after global normothermic ischemia. Methods. After stabilization and loading of indo 1-AM in Kreb’s solution (KR), each heart was perfused with either KR or 1 of 4 CP solutions before 37°C, 30 min ischemia followed by reperfusion with KR. The KR solution contained, in mM, 4.5 KCl, 2.4 MgCl2 and 2.5 CaCl2; the CP solutions had in addition to 18 KCl: CP 1 (control CP): 2.4 MgCl2, 2.5 CaCl2; CP 2: 7.2 MgCl2, 2.5 CaCl2; CP 3, 7.2 MgCl2, 1.25 CaCl2; CP 4: 2.4 MgCl2, 1.25 CaCl2.
Results. In the KR group [Ca2+]i markedly increased on early reperfusion while functional return (LVP, dLVP/dt(max and min)) was much reduced; each CP group led to reduced [Ca2+]i loading and improved function. The rates of cytosolic Ca2+ fluxes (d[Ca2+]/dtmax and d[Ca2+]/dtmin) increased significantly compared to baseline in the KR group, but were mostly suppressed in the CP groups, and d[Ca2+]/dtmin was lower after CP 4 compared to CP 1 on reperfusion. At 60 min reperfusion, LVP area to [Ca2+] area and cardiac efficiency to phasic [Ca2+] relationships were shifted after KR, but not after CP 1-4. With similar functional recovery, [Ca2+] transient and [Ca2+] area were significantly lower after CP 4 than after CP 1.
Conclusion. Increasing [MgCl2] (CP 2 and 3) did not improve cardiac function or reduce Ca2+ transients on reperfusion better than the other CP groups, but reducing [CaCl2] (CP 3 and 4) was more effective in reducing [Ca2+] transients on reperfusion after global ischemia.