Role of beta-endorphins in silent myocardial ischemia

• Published in: The American journal of cardiology Vol. 58; no. 6; pp. 428 - 430
• Main Authors: Weidinger, Franz, Hammerle, Alfons, Sochor, Heinz, Smetana, Ronald, Frass, Michael, Glogar, Dietmar
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.09.1986; Elsevier
• Subjects: beta-Endorphin; Biological and medical sciences; Blood Pressure - drug effects; Cardiology. Vascular system; Coronary heart disease; Electrocardiography; Endorphins - physiology; Exercise Test; Heart; Heart Rate - drug effects; Humans; Male; Medical sciences; Middle Aged; Myocardial Infarction - blood; Myocardial Infarction - physiopathology; Naloxone - pharmacology; Pain - physiopathology; Physical exercise; Human; Cardiovascular disease; Exercise tolerance test; Opiates; Serum; Asymptomatic; β-Endorphin; Coronary heart disease
• ISSN: 0002-9149; 1879-1913
• DOI: 10.1016/0002-9149(86)90009-3

The reason for the absence of pain perception in silent myocardial ischemia is unknown. A role of increased endorphinic activity in patients with silent ischemia has been postulated. To further investigate this hypothesis, 10 men with documented coronary artery disease and previous positive electrocardiographic findings during exercise without anginal pain were studied. Six healthy volunteers served as control subjects. The protocol included 2 bicycle exercise tests, the first test serving as baseline and the second performed after administration of naloxone, a specific opiate antagonist. Plasma β-endorphin levels were measured by radioimmunoassay in both tests at rest, at peak exercise level and after recovery. All patients underwent thallium-201 scintigraphy after coronary vasodilation to provide an additional independent marker of ischemia. All patients showed stress-induced reversible perfusion abnormalities. No patient reported pain after naloxone application. Exercise duration, blood pressure and heart rate were not significantly altered by naloxone. Plasma β-endorphin levels ranged from 18 ± 6 pg/100 μl (mean ± standard deviation) at rest to 22 ± 6 pg/100 μl during exercise in the patient group and from 20 ± 5 to 27 ± 9 pg/100 μl in the control subjects. Thus, there was no significant increase of plasma β-endorphins during exercise or after naloxone administration, nor was there any difference observed between patients and control group. These data support the view that endorphinic activity does not play an essential role in the pathophysiology of silent myocardial ischemia.