Basis of the depressor action of adenosine phosphates

Abstract

It was previously shown that, when injected intravenously in the rat, ADP is a considerably more potent blood pressure lowering agent than adenosine, AMP, or ATP. The basis of this difference was investigated. It was found that the depressor action of all four compounds depends largely, if not entirely, upon dilation of peripheral blood vessels and that vagal reflex action, cardiac slowing, and pulmonary vasoconstriction do not contribute to the lowering of the blood pressure in the dose range studied. Adenosine and AMP are less effective vasodilators than ADP. ATP is an equally or possibly more effective vasodilator than ADP when injected intra-arterially but considerably less effective when injected intravenously. It is concluded that ATP, but not ADP, is to a large extent trapped or inactivated in the pulmonary circulation. For this reason ADP is the most potent depressor agent when the compounds are injected intravenously.