Exercise capacity after acute aminophylline administration in angina pectoris.
Exercise-induced ischemia is generally attributed to an increase in myocardial demand in the presence of coronary stenosis limiting flow supply. An additional mechanism--the occurrence of coronary steal due to excessive endogenous adenosine release--has also been hypothesized. The effect of adenosine receptor blocking by aminophylline in effort ischemia was tested in 8 patients with stable effort-induced angina pectoris, reproducible positive exercise stress tests and angiographically assessed coronary artery disease. Following double-blind, randomized intravenous infusion of aminophylline (3 mg/kg over 3 minutes) or placebo (20 ml of saline over 3 minutes), the patients underwent upright bicycle exercise stress tests on 2 consecutive days. After aminophylline, there was an increase in work tolerance (aminophylline 7.5 +/- 1.8 minutes of exercise vs placebo 5.4 +/- 1.5 minutes; p less than 0.05). There was a parallel increase in the ischemic threshold, evaluated with the rate-pressure product (mm Hg X beats/min X 100(-2)) at 0.1 mV of ST-segment depression (221 +/- 35 vs 184 +/- 20; p less than 0.01). Thus, at a dosage that should effectively inhibit adenosine receptors, aminophylline infusion exerts a beneficial effect on exercise-induced ischemia, possibly through the prevention of myocardial flow maldistribution elicited by excessive adenosine release during effort.
Picano
E
E
CNR Institute of Clinical Physiology, Pisa, Italy.
Pogliani
M
M
Lattanzi
F
F
Distante
A
A
L'Abbate
A
A
D000628:Aminophylline / Q000627:therapeutic use*; D000787:Angina Pectoris / Q000188:drug therapy* / Q000503:physiopathology; D004311:Double-Blind Method; D005080:Exercise Test; D006801:Humans; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion; D011897:Random Allocation; D011983:Receptors, Purinergic / Q000187:drug effects
D011983:Receptors, Purinergic; D000628:Aminophylline