Affiliation:
1. From the Anesthesiology Research Laboratory, Departments of Anesthesiology, Medicine (Cardiovascular Diseases), and Physiology, and Cardiovascular Research Center, Medical College of Wisconsin, and Veterans Affairs Medical Center, Milwaukee.
Abstract
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).
Methods and Results
—Guinea pig hearts were initially perfused at 37°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°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.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Physiology (medical),Cardiology and Cardiovascular Medicine
Reference39 articles.
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3. The effects of calcium and magnesium in hyperkalemic cardioplegic solutions on myocardial preservation
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