 Amrinone has been shown to increase the contractions initiated in the heart by high gain calcium induced calcium release (CICR).The positive inotropic effect of amrinone is mediated by the selective enhancement of high gain CICR which contributes to the contraction of myocytes by phosphorylation through cAMP dependent protein kinase A (PKA) and Ca2+ calmodulin kinase pathways.Increases cardiac contractility, vasodilator.