Comparison of the Ca2+ movement by activation of alpha1-adrenoceptor subtypes in HEK-293 cells.
We studied the Ca2+ movement induced by activation of alpha1A-, alpha1B- and alpha1D-adrenoceptor subtypes in transfected HEK-293 cells with the fura-2 probe. All these alpha1-AR subtypes induced both Ca2+ release and Ca2+ entry. The effect on Ca2+ release in alpha1b transfected HEK-293 cells was bigger than that in alpha1a and alpha1d transfected HEK-293 cells, and the effects on Ca2+ entry were the same in alpha1a, alpha1b and alpha1d transfected HEK-293 cells. The Ca2+ entry was inhibited by 1 mM NiSO4, but not by nifedipine. Cyclopiazonic acid (CPA) produced a biphasic Ca2+ signal response in Ca2+ medium, and only induced a transient response in Ca2+-free medium. After depletion of CPA-sensitive Ca2+ pool by 10 microM CPA in Ca2+-free medium, 10 microM adrenaline (Adr) still transiently increased [Ca2+]i in three different alpha1-adrenoceptor subtype transfected HEK-293 cells. However, after depletion of adrenaline-sensitive Ca2+ pool by 10 microM Adr, CPA transiently elevated [Ca2+]i only in alpha1a and alpha1d transfected HEK-293 cells, not in alpha1b transfected HEK-293 cells. U73122, a phospholipase C (PLC) inhibitor, inhibited both Ca2+ release and Ca2+ entry induced by activation of alpha1A alpha1B and alpha1D subtypes in transfected HEK-293 cells. These results suggest that HEK-293 cell line contains two functionally separate intracellular Ca2+ pools, CPA-sensitive and Adr-sensitive pools. Activation of alpha1B-AR stimulates Ca2+ release from both CPA-sensitive and Adr-sensitive Ca2+ pools. Alpha1A and alpha1D subtypes induce Ca2+ release only from Adr-sensitive Ca2+ pool.
Tao
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Department of Pharmacology, Sun Yat-Sen University of Medical Sciences, Guangzhou, China.
Guan
Y Y
YY
He
H
H
Han
C
C
Zhang
Y Y
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Sun
J J
JJ
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002460:Cell Line; D006224:Cricetinae; D004837:Epinephrine / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D017136:Ion Transport; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D012433:Ryanodine / Q000494:pharmacology; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism
D007211:Indoles; D018340:Receptors, Adrenergic, alpha-1; D012433:Ryanodine; D002110:Caffeine; D010738:Type C Phospholipases; D011188:Potassium; D002118:Calcium; C000543:cyclopiazonic acid; D004837:Epinephrine