[Pathways of signal transduction of intracellular Ca2+ increase mediated by three subtypes of alpha 1-adrenoceptor in HEK293 cells].
In HEK293 cell lines in which alpha 1a-, alpha 1b- or alpha 1d-adrenoceptor subtypes were stably expressed, fluorescence intensities due to traces of Ca2+ were investigated using fura-2/AM with the aim of exploring signal transduction pathways of intracellular Ca2+ increase mediated by these receptor subtypes. Pertussis toxin had no effect on [Ca2+]i increase mediated by all three subtypes of alpha 1-adrenoceptors. However, U-73122 and PMA could inhibited the [Ca2+]i increase induced by NE, which was not affected by Foskolin and Rp-cAMPs. Pretreatment with calphostin C abolished the [Ca2+]i response to PMA. Quercetin and tyrphostin inhibited maximal [Ca2+]i increase but had no effect on the plateau phase in all the three transfected cells. In the HEK293 cells, the phosphatide-Ca2+ signalling system mediated by the 3 subtypes of alpha 1-AR was brought into play by activation of phospholiphase C via coupling with PTX-insensitive G proteins. PKC system inhibited both mobilization of internal Ca2+ stores and the Ca2+ influx across the plasma membrane. Tyrosine kinase, but not cAMP system, might participate in such Ca2+ signalling.
Li
H W
HW
Institute of Vascular Medicine, Third Hospital, Beijing Medical University, Beijing 100083.
Geng
Q M
QM
Zhang
Y Y
YY
Han
Q D
QD
D000818:Animals; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D006224:Cricetinae; D004622:Embryo, Mammalian; D019204:GTP-Binding Proteins / Q000378:metabolism; D007668:Kidney / Q000166:cytology; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism
D018340:Receptors, Adrenergic, alpha-1; D011493:Protein Kinase C; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D002118:Calcium