Role of beta-endorphins in analgesia associated with reactive hyperemia

The role of plasma rhythm of beta-endorphin (beta-E) levels during reactive hyperemia was investigated in patients undergoing aortofemoral arteriography (n = 24). Two groups of patients were studied; one undergoing morning (AM; n = 15) and the other, afternoon (PM; n = 9) procedures. Arterial blood samples for assay of plasma beta-E were obtained during the following time intervals: baseline or prior to vascular occlusion (T1); after 2 1/2 minutes of vascular occlusion (T2), and 1 (T3) and 2 minutes (T4) after release of the pressure cuffs. Baseline beta-E levels of each group were elevated over nonstressed individuals and no significant difference occurred over the course of the procedure with either the AM or PM groups. Examination of changes in beta-E levels in individual patients yielded a different pattern. In the AM group, nine patients doubled their plasma beta-E levels from T1 to T2 (P less than .05) and remained elevated during T3 and T4 (P less than .05). Other members of the group n = 6 also had high baseline levels of beta-E and these levels declined from T2 to T4 (P less than .05). In the PM group, baseline beta-E levels were elevated in comparison with normals in five patients who exhibited similar increment in beta-E levels from T1 to T2 as the AM group, but the results were not significant. Other members of the group (n = 4) also had high baseline beta-E levels and the levels declined from T2 to T4 as in the AM group.(ABSTRACT TRUNCATED AT 250 WORDS)