Beta-enolase in blood plasma during open heart surgery--comparing with CK-MB and CA-III in blood plasma

Enolase isozyme composed of the beta subunit (alpha beta or beta beta enolase) is distributed predominantly in the heart and skeletal muscles. Concentrations of beta-enolase (beta subunit of enolase) in blood plasma samples serially taken from 18 patients, who received mitral valve replacement, were estimated by using a highly sensitive enzyme immunoassay method and compared with those of CK-MB in the same samples. Plasma beta-enolase levels, that were 6.60 +/- 3.84 ng/ml at the beginning of anesthesia, increased rapidly after reperfusion reaching the plateau more than 100 ng/ml between 2 to 12 hours, showing two peak (116 +/- 45.7 ng/ml at 4 hours and 112 +/- 48.1 ng/ml at 12 hours after reperfusion), and then decreased slowly remaining high levels even when plasma CK-MB levels became normal. The beta-enolase concentrations were significantly higher in coronary sinus samples than in arterial samples early after reperfusion. Since plasma carbonic anhydrase III, which is known to be localized only in the skeletal muscle, did not increase during the surgery, it is suggested that the major portion of elevated plasma beta-enolase levels were derived from the heart muscle. Plasma levels of beta-enolase increased as quickly as those of CK-MB after reperfusion and kept high levels longer than those of CK-MB. These results indicate that the determination of beta-enolase in plasma may be useful for estimating the myocardial damage during open heart surgery.