The effect of transcutaneous electrical nerve stimulation (TENS) on catecholamine metabolism during pacing-induced angina pectoris and the influence of naloxone
Journal/Book: Pain. 1990; 41: 27-34.
Abstract: Two invasive studies (invasive sludy I and invasive study II) showed positive effects of transcutaneous electrical nerve stimulation (TENS) in pacing-induced angina pectoris in terms of increased tolerance to pacing. improved lactate metabolism and Iess anginal pain.lnvasive study I demonstrated a decrease in left ventricular afterload by TENS treatment as reflected by a fall in systolic blood pressure, and this fact was thought to be explained by reduced sympathetic acclivity since arterial levels of epinephrine and norepinephrine dropped during TENS in TENS responders.In invasive study II, the influence of naloxone on the effects of TENS in pacing-induced angina pectoris was studied in 11 patients with severe coronary artery disease. The patients were catheterized and treated with TENS on 2 occasions one with a single intravenous (i.v.) dose of saline as placebo and one with a single i.v. dose of 50 mg nalaxone, double-blind, in random order. Treatment with TENS increased tolerance to pacing (P < 0.01 with placebo and P < 0.01 wilh naloxone, respectively) and improved lactate metabolism (P<0.05 with placebo and P<0.01 with naloxone, respectively). The positive effects of TENS were thus reproducible and not reversed by single i.v. doses of naloxone. The results of this study indicate that the effects of TENS on the heart are not mediated by beta-endorphin but do not exclude activation of more short-acting opioids like delta or kappa receptor agonists (met-enkephalin and/or dynorphin) since naloxone has a low affinity for these receptors. It is also possible that non-opioid mechanisms are of importance. However, this study did not exhibit any data that confirmed the hypothesis that the effects of TENS in angina pectoris can be explained by a reduced sympathetic activity, since the arterial levels of epinephrine and norepimephrine did not change and the systolic blood pressure did not decrease during TENS treatment.
Keyword(s): Angina pectoris