Reduced cytosolic Ca(2+) loading and improved cardiac function after cardioplegic cold storage of guinea pig isolated hearts.
BACKGROUND
Hypothermia is cardioprotective, but it causes Ca(2+) loading and reduced function on rewarming. The aim was to associate changes in cytosolic Ca(2+) with function in intact hearts before, during, and after cold storage with or without cardioplegia (CP).


RESULTS
Guinea pig hearts were initially perfused at 37 degrees C with Krebs-Ringer's (KR) solution (in mmol/L: Ca(2+) 2.5, K(+) 5, Mg(2+) 2.4). One group was perfused with CP solution (Ca(2+) 2.5, K(+) 18, Mg(2+) 7.2) during cooling and storage at 3 degrees C for 4 hours; another was perfused with KR. LV pressure (LVP), dP/dt, O(2) consumption, and cardiac efficiency were monitored. Cytosolic phasic [Ca(2+)] was calculated from indo 1 fluorescence signals obtained at the LV free wall. Cooling with KR increased diastolic and phasic [Ca(2+)], whereas cooling with CP suppressed phasic [Ca(2+)] and reduced the rise in diastolic [Ca(2+)]. Reperfusion with warm KR increased phasic [Ca(2+)] 86% more after CP at 20 minutes and did not increase diastolic [Ca(2+)] at 60 minutes, compared with a 20% increase in phasic [Ca(2+)] after KR. During early and later reperfusion after CP, there was a 126% and 50% better return of LVP than after KR; during later reperfusion, O(2) consumption was 23% higher and cardiac efficiency was 38% higher after CP than after KR.


CONCLUSIONS
CP decreases the rise in cardiac diastolic [Ca(2+)] observed during cold storage in KR. Decreased diastolic [Ca(2+)] and increased systolic [Ca(2+)] after CP improves function on reperfusion because of reduced Ca(2+) loading during and immediately after cold CP storage.
Stowe
D F
DF
Anesthesiology Research Laboratory, Department of Anesthesiology, Medical College of Wisconsin, and Veterans Affairs Medical Center, Milwaukee, WI, USA.dfstowe@mcw.edu
Varadarajan
S G
SG
An
J
J
Smart
S C
SC
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002314:Cardioplegic Solutions / Q000494:pharmacology; D015925:Cryopreservation; D003600:Cytosol / Q000737:chemistry*; D006168:Guinea Pigs; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D015425:Myocardial Reperfusion / Q000379:methods; D009206:Myocardium / Q000648:ultrastructure; D019188:Organ Preservation Solutions; D013997:Time Factors; D014021:Tissue Preservation
D002314:Cardioplegic Solutions; D019188:Organ Preservation Solutions; D002118:Calcium