Abstract
The hemodynamic effects on both pulmonary and systemic circulation of 10 mg/kg intravenously injected dibutyryl cyclic AMP (db-cAMP), a cyclic AMP derivative, were studied using Swan-Ganz catheterization and hemodilution methods with the following results:
1. Cardiac output increased about 40% maximally due to increased stroke volume and heart rate. Enhanced stroke volume played a more important role in cardiac output increase than did the heart rate.
2. Peripheral resistance was lowered, as evidenced by the increased cardiac output and decreased arterial pressure.
3. Pulmonary vascular resistance was also seen to be lowered slightly, from the relatively constant pulmonary arterial pressure and increased cardiac output.
4. The effects noted attained their peak values at 10 to 20 minutes after injection, continued for about 20 minutes, and returned gradually to the control values in 90 minutes.
From these results, db-cAMP at 10 mg/kg was found to have little adverse effect on pulmonary circulation. Therefore the usefulness of this drug as a ther-apeutic agent in the treatment of shock characterized by low cardiac output along with increased peripheral resistance may be presumed, provided that it be administered with great care for low circulating volume.
