The purpose of this study was to evaluate whether the addition of
verapamil hydrochloride to oxygenated
glucose-rich
cardioplegic solution would improve myocardial preservation. The Langendorff preparation of the isolated rat heart was used. Groups of normal (WKY) and hypertrophied (SHR) hearts were treated by five different cardioplegic methods and subjected to 90 or 30 minutes of
ischemia at 28 degrees to 29 degrees C and reperfusion at 37 degrees C. The following
cardioplegic solutions were used: Group A, cold (16 degrees C) Krebs-Henseleit (KH)
glucose free only; Group B, KH with KCL (30 mEq/L) (16 degrees C); Group C, same as B with
verapamil (10 microM); Group D, perfusion with oxygenated KH
solution containing KCL (30 mEq/L) for 15 minutes prior to
ischemia; and Group E, same as D with
verapamil (10 microM). Recovery of contraction amplitude,
ischemic contracture, coronary perfusate volume, the amount of
creatine kinase in the coronary perfusate, heart rate, time of revival, O2 consumption, and
ischemic contracture were measured. After 30 minutes of
ischemia, we did not find any significant difference among the combinations tested with respect to contraction amplitude recovery. The hearts recovered fully. After 90 minutes of
ischemia, we found that the best-protected groups in the normal hearts were Groups D and E. In the hypertrophied hearts, the addition of
verapamil to the enhancement
solution was harmful. The use of enhancement
solution without
verapamil prior to
ischemia provided the best myocardial protection in the hypertrophied hearts.