Coronary vasodilator responses to hypoxia before and after aminophylline.

1. In previous studies adenosine has been postulated to be the mediator in coronary blood flow regulation and aminophylline was found to inhibit the coronary vasodilator action of adenosine. The present study was performed to determine whether aminophylline inhibits coronary vasodilatation induced by hypoxia.2. Coronary and systemic haemodynamic and metabolic effects of hypoxia were studied in anaesthetized dogs before and after aminophylline. Aminophylline did not influence coronary vasodilatation induced by hypoxia.3. These results are held not to lend support to the hypothesis that adenosine is the metabolite responsible for the regulation of coronary blood flow.