[Plasma beta-endorphin level in "silent" myocardial ischemia during Holter ECG monitoring].

The results from recent studies suggest that the endogenous opioid beta-endorphin (beta-E) is related to pain modulation. Therefore, plasma beta-E levels were studied in 23 patients with essential hypertension (EH) and in 7 patients with coronary artery disease (CAD) during asymptomatic ischemic events and in 5 patients with CAD during symptomatic ischemic events. Blood samples for beta-E were taken at the moment of silent ST depression, pointed with alarm by the real time ECG monitor "Q Med Monitor" (USA). Control blood samples were taken under the same conditions without ischemic events. Control plasma beta-E levels were significantly higher (p less than 0.01) in patients with EH as compared to that in both groups of patients with CAD (22.9 +/- 4.0 vs 7.0 +/- 1.9 and 4.5 +/- 1.6 pmol/l). At the time of silent ischemia, beta-E showed a significant increase in patients with EH (+10.1 +/- 2.1 pmol/l, p less than 0.01) and in patients with CAD (+10.7 +/- 1.3 pmol/l, p less than 0.05) as compared to the control levels. However, plasma beta-E showed no increase (+1.0 +/- 0.6 pmol/l, p greater than 0.1) during symptomatic ischemia as compared to the control levels. Thus, differences in the circulating levels of beta-E may be associated with the presence or absence of pain during myocardial ischemia.