Calcium efflux through cardiac calcium channels reconstituted into liposomes--flux measurement with fura-2.
Cardiac Ca2+ channels were solubilized and reconstituted into liposomes, and Ca2+ efflux from the proteoliposomes was measured with the fluorescent dye fura-2. The Ca2+ efflux, induced by K+ depolarization, was sensitive to Ca2+ channel modulators such as nifedipine, D-600 and Bay K 8644, and was dependent on the membrane potential. Furthermore, the efflux was increased by phosphorylation of proteoliposomes with cAMP-dependent protein kinase. These results suggest that the reconstituted cardiac Ca2+ channels retain the voltage-dependent gating properties, pharmacological sensitivities and modulation by phosphorylation.
Kameyama
A
A
National Institute for Physiological Sciences, Okazaki, Japan.
Nakayama
T
T
D000818:Animals; D001572:Benzofurans; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002417:Cattle; D016257:Fura-2; D006352:Heart Ventricles / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism*; D007700:Kinetics; D008081:Liposomes; D009206:Myocardium / Q000378:metabolism*; D011510:Proteolipids / Q000378:metabolism*; D012508:Sarcolemma / Q000378:metabolism
D001572:Benzofurans; D002121:Calcium Channel Blockers; D007473:Ion Channels; D008081:Liposomes; D011510:Proteolipids; C020485:proteoliposomes; D002118:Calcium; D016257:Fura-2