INTRAVENOUS DIADENOSINE TETRAPHOSPHATE IN DOGS - CARDIOVASCULAR EFFECTS AND INFLUENCE ON BLOOD-GASES

Diadenosine tetraphosphate (AP(4)A) has a considerable vasodilating ef fect. Its dose was adjusted to decrease mean arterial pressure (MAP) b y 20%, 40%, 50%, 60%, and 80% of the pretreatment value, and the effec ts on hemodynamics and gas exchange were evaluated. AP,A produced a do se-dependent decrease in MAP within the range of doses which decreased blood pressure by up to 60%. Heart rate remained constant at hypotens ion levels of 40% or less, but decreased significantly at hypotension levels of 50% or more. Cardiac output increased significantly at hypot ension levels of 40% or less. Systemic vascular resistance (SVR) showe d a significant decrease at that time. No significant changes were obs erved in central venous pressure and pulmonary capillary wedge pressur e at any level of hypotension. Arterial oxygen tension and calculated pulmonary shunt ratio showed no change. Base excess and pH were decrea sed significantly with a 60% or 80% fall of blood pressure. In conclus ion, AP(4)A seems to ace on the resistance vessels and cause a decreas e in SVR.