ORIGINAL ARTICLES  CARDIAC SECTION 

The Journal of Cardiovascular Surgery 2004 February;45(1):1-13

Copyright © 2004 EDIZIONI MINERVA MEDICA

lingua: Inglese

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.