Mechanism of ATP-induced [Ca(2+)](i) mobilization in rat basilar smooth muscle cells.
OBJECTIVE
We have previously reported that extracellular ATP activates P(2u) receptors and increases intracellular free Ca(2+) ([Ca(2+)](i)) by G protein/phospholipase C/inositol 1,4,5-triphosphate pathways in cerebral artery smooth muscle cells. However, the possible contribution of other signaling pathways remains unclear. This study was undertaken to investigate the role of protein tyrosine kinase (PTK) and mitogen-activated protein kinase (MAPK) in mediating ATP-induced Ca(2+) mobilization in rat basilar artery smooth muscle cells (RBASMCs).


METHODS
RBASMCs were freshly isolated, and [Ca(2+)](i) was monitored by fura 2 microfluorimetry. MAPK phosphorylation was studied by the Western blot technique.


RESULTS
ATP produced a biphasic [Ca(2+)](i) response, which consists of releasing Ca(2+) from internal stores and influx from extracellular space. PTK inhibitors tyrphostin 51 and genistein inhibited [Ca(2+)](i) response to ATP. Tyrphostin A1, an inactive analogue of tyrphostins, failed to reduce the ATP-induced response. MAPK kinase inhibitor PD98059, but not U0126, reduced the ATP-induced [Ca(2+)](i) response. Phosphatidylinositol 3-kinase (PI3-K) tyrosine kinase inhibitor wortmannin, but not janus tyrosine kinase (JAK2) inhibitor AG490, partially inhibited the [Ca(2+)](i) response induced by ATP. In addition, ATP enhanced MAPK phosphorylation in a concentration- and time-dependent manner, and genistein, tyrphostin 51, PD98059, and U0126 inhibited MAPK phosphorylation.


CONCLUSIONS
Extracellular ATP produced [Ca(2+)](i) elevation and MAPK phosphorylation in RBASMCs, and the effect was regulated by PTK. The role of MAPK in ATP-induced [Ca(2+)](i) elevation is not clear. PI3-K tyrosine kinase and JAK2 tyrosine kinase may not play an important role in the ATP-induced [Ca(2+)](i) response in RBASMCs.
Aoki
K
K
Department of Neurosurgery, University of Mississippi Medical Center, Jackson 39216-4505, USA.
Zubkov
A Y
AY
Parent
A D
AD
Zhang
J H
JH
D000255:Adenosine Triphosphate / Q000502:physiology*; D000818:Animals; D001488:Basilar Artery / Q000166:cytology*; D015153:Blotting, Western; D020013:Calcium Signaling / Q000502:physiology*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000737:chemistry; D005260:Female; D005470:Fluorometry; D007424:Intracellular Fluid / Q000737:chemistry; D053614:Janus Kinase 2; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008832:Microchemistry; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D011518:Proto-Oncogene Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley
D000255:Adenosine Triphosphate; D004791:Enzyme Inhibitors; D053614:Janus Kinase 2; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; C507927:Jak2 protein, rat