Activation of calcium mobilization and calcium influx by alpha 1-adrenergic receptors in a smooth muscle cell line.
Alpha 1-adrenergic receptor (alpha 1R) mediated increases in the cytosolic levels of free Ca+2 and the inositol phosphates were measured in a smooth muscle cell line, DDT1. Norepinephrine (NE) stimulated a rapid increase in cytosolic Ca+2 by two distinct components: 1) release of Ca+2 from intracellular sites (mobilization), and 2) influx of extracellular Ca+2. The mobilization component was not affected by removal of extracellular Ca+2 or addition of La+3 or Co+2 to the buffer. The influx component was abolished by EGTA, La+3, or Co+2, but was not affected by the voltage-operated Ca+2 channel blockers diltiazem or nifedipine. Depolarization of DDT1 cells with 100 mM KCl or with gramicidin did not induce Ca+2 influx. NE also increased inositol trisphosphate to 78% over basal levels within 1 minute. These results suggest that alpha 1R on DDT1 cells are coupled to both the mobilization of intracellular Ca+2 and to receptor-operated Ca+2 channels in the plasma membrane, and that polyphosphoinositide hydrolysis may play a role in these phenomena.
Reynolds
E E
EE
Dubyak
G R
GR
D000634:Aminoquinolines; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002460:Cell Line; D003035:Cobalt / Q000494:pharmacology; D006224:Cricetinae; D004533:Egtazic Acid / Q000494:pharmacology; D005260:Female; D007295:Inositol Phosphates / Q000378:metabolism; D007811:Lanthanum / Q000494:pharmacology; D007890:Leiomyosarcoma / Q000378:metabolism; D008297:Male; D009130:Muscle, Smooth / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D014594:Uterine Neoplasms / Q000378:metabolism
D000634:Aminoquinolines; D002121:Calcium Channel Blockers; D007295:Inositol Phosphates; D011942:Receptors, Adrenergic, alpha; D003035:Cobalt; D004533:Egtazic Acid; D007811:Lanthanum; C035739:Quin2; D002118:Calcium; D009638:Norepinephrine; D010646:Phentolamine