USEFULNESS OF PLASMA BETA-ENDORPHIN LEVEL, PAIN THRESHOLD AND AUTONOMIC FUNCTION IN ASSESSING SILENT-MYOCARDIAL-ISCHEMIA IN PATIENTS WITH AND WITHOUT DIABETES-MELLITUS

The differences between diabetic and nondiabetic Patients with silent myocardial ischemia were investigated. Based on the results of previou s exercise testing, a total of 110 patients (15 diabetic and 95 nondia betic) with exercise-induced myocardial ischemia were divided into the following 3 groups: 15 diabetics with silent myocardial ischemia, 49 nondiabetics with silent myocardial ischemia, and 46 nondiabetics with anginal symptoms. All patients underwent treadmill exercise testing a nd 24-hour ambulatory electrocardiographic recording. Before and durin g exercise, blood samples from the antecubital vein were obtained to d etermine the beta-endorphin levels, and the pain threshold of each pat ient was measured with the electrical skin stimulation test. Furthermo re, with regard to the ambulatory electrocardiographic recording, the mean of the SDs of all normal sinus RR intervals during successive 5-m inute recording periods over 24 hours was analyzed and considered as a n index of the autonomic function. The beta-endorphin level during exe rcise was significantly greater in nondiabetic patients with silent is chemia than in diabetic ones. The SD mean was significantly less in th e diabetic group than in the 2 nondiabetic ones. The findings suggest that the role of beta endorphin in diabetic patients with silent myoca rdial ischemia may be less significant than in nondiabetic ones; there fore, a diabetic neuropathy that affects the autonomic pain fibers tha t innervate the heart may be involved in the mechanism of silent myoca rdial ischemia in diabetics.