A coronary vasoconstrictor substance is present in regular and “decaffeinated” forms of both percolated and instant coffee

Coffee contains a previously unrecognized vasoactive material with potent constrictor action on the coronary arteries of the heart when tested in two types of preparations. Contractions of beef coronary vessel strips developed in response to both regular and caffeine-reduced forms of coffee (0.02 – 1.0 ml/15 ml Krebs solution), and they were specifically blocked by the cholinergic antagonist atropine. A perfused slab of beef left ventricle also showed a vasoconstrictor response to coffee which was antagonized by atropine. In contrast, tea, in comparable volumes to those of coffee elicited only vascular relaxation, as did the methylxanthine caffeine. The possibility should be considered that the cholinomimetic substance described here is linked to the reported increased incidence of myocardial infarction in coffee but not in tea drinkers.