Inhibition of cardiac sarcolemmal sodium-calcium exchanger by glycerophosphoinositol 4-phosphate and glycerophosphoinositol 4-5-bisphosphate.
The enrichment in phosphatidylinositol 4-phosphate and phosphatidylinositol 4-5-bisphosphate of cardiac sarcolemmal vesicles stimulate Na+/Ca2+ exchange activity. On the contrary the deacylation products of polyphosphoinositides are powerful inhibitors of Na+/Ca2+ exchange: half maximal inhibition of 1.6 and 2.1 microM have been observed for glycerophosphoinositol 4-phosphate and glycerophosphoinositol 4-5-bisphosphate, respectively. The data indicate a bidirectional regulation of Na+/Ca2+ exchanger and suggest that phosphorylated glycerophosphoinositols can be regarded as novel signal transducers of intracellular Ca2+ regulation in heart cell.
Luciani
S
S
Department of Pharmacology, University of Padova, Italy.
Antolini
M
M
Bova
S
S
Cargnelli
G
G
Cusinato
F
F
Debetto
P
P
Trevisi
L
L
Varotto
R
R
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000037:antagonists & inhibitors*; D002417:Cattle; D006352:Heart Ventricles; D007295:Inositol Phosphates / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000494:pharmacology*; D012508:Sarcolemma / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D019831:Sodium-Calcium Exchanger
D002352:Carrier Proteins; D007295:Inositol Phosphates; D018129:Phosphatidylinositol Phosphates; D019831:Sodium-Calcium Exchanger; C062528:glycero-3-phosphoinositol 4-phosphate; C091533:glycerophosphoinositol 4,5-bisphosphate; D012964:Sodium; D002118:Calcium