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Indexed/Abstracted in: BIOSIS Previews, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 1,632
Online ISSN 1827-191X
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.