Adenosine-provoked angina pectoris-like pain--time characteristics, influence of autonomic blockade and naloxone.

In a study to characterize the time characteristics and the influence of blockade of beta, cholinergic and opioid receptors on the chest pain induced by adenosine, this agent was given as a bolus into a peripheral vein of six healthy volunteers (4 men) 24-45 years of age. On the first day the maximum tolerable dose was determined in each case. On the second day three doses of adenosine (1/3, 2/3, and a full maximum tolerable dose) and three doses of placebo were given as single blind doses in randomized order. Thereafter metoprolol (10 mg to males, 8 mg to females), followed by 1 mg atropine and then 0.4 mg naloxone were given intravenously. After each agent the test procedure was repeated. Heart rate and atrio-ventricular blocks were recorded by electrocardiography and respiration by dynamic spirometry. One minute after each dose of adenosine, the chest pain was scored. The maximum tolerable dose of adenosine was 8.0-15.9 mg. All subjects experienced angina pectoris-like pain. Following injection, onset of respiratory stimulation, AV-block and chest pain occurred after 14 +/- 4.0, 19 +/- 5.4 and 21 +/- 6.4 s, the differences being highly significant. Maximal respiratory stimulation occurred after 18 +/- 4.6, not statistically different from the onset of AV-block which in its turn occurred earlier (P less than 0.005) than the time for maximal central chest pain, 29 +/- 7.8 seconds. Metoprolol induced a 20% slowing of heart rate. After atropine there was a 30% faster heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

RCT Entities:   Population Interventions Outcomes