positive inotropic actions in the normal guinea pig cardiac muscle and the activities required to produce electrical and mechanical responses in the depolarized muscle were examined using epinephrine , dopamine , metanephrine , aminophylline , histamine , serotonin , tyramine , tetraethylammonium ( tea ) , tetramethylammonium ( tma ) , and x-537a , a calcium ionophore .
C0014563
epinephrine
C0025562
metanephrine