when isolated perfused guinea pig heart were perfused with 10-5-m papaverine , a potent inhibitor of cyclic amp phosphodiesterase activity , myocardial cyclic amp concentration increased significantly from 1.7 plus and minus 0.2 ( se ) pmoles/mg protein ( n equal 12 ) to 3.3 plus and minus 0.2 pmoles/mg protein ( n equal 12 ) , and the percent of phosphorylase aual 6 ) ( p less than 0.01 ) .
C0018787
heart
C0027061
myocardial