Improved myocardial function has been reported in experimental animals and man following the infusion of soluble cyclic adenosine monophosphate (c-AMP). It is the objective of this research (1) To compare the relative effectiveness on myocardial function of increasing intracellular c-AMP levels by phosphodiesterase inhibition, adenyl cyclase stimulation, or introduction of cyclic phosphate compounds known to simulate c-AMP function. (2) To determine whether this induced increase in intracellular c-AMP level is associated with an improvement in myocardial function in shock due to a variety of causes. (3) To study possible synergistic effects of the infusion of commonly used vasoactive drugs such as isoproterenol, Glucagon, and norepinephrine on myocardial function in intact experimental animals before and following shock due to a variety of causes. (4) To measure the levels of c-AMP and phosphodiesterase in myocardium, lung and liver before and following the change effected in #1 above.