possible mechanisms for an inositol phosphate-mediated positive inotropic effect are : ( i ) release of ca2+ from the sarcoplasmic reticulum , elicited by ip3 , ( ii ) increase in ca2+ sensitivity of the contractile proteins , elicited by ip3 , inositol tetrakisphosphate ( ip4 ) and/or dg , ( iii ) increase in slow ca2+ inward current , elicited directly by ip4 and/or indirectly by dg through a phosphorylation of the protein kinase c substrate in the sarcolemma .
C0021554
inositol phosphate
C0021547
inositol