Endothelin-1 stimulated capacitative Ca2+ entry through ET(A) receptors of a rat brain-derived type-1 astrocyte cell line, IA-1g1.
The present study demonstrated that endotheline-1 (ET-1) stimulated a biphasic (transient and sustained) increase in [Ca(2+)](i) and signaling was blocked by BQ123 and inhibited by BQ788. RT-PCR analysis revealed that ET(A) was expressed more than ET(B) mRNA-suggesting that ET(A) is the major receptor. Simply reintroducing Ca(2+) in the buffer stimulated a sustained increase in [Ca(2+)](i) and the effect was inhibited by U73122, thapsigargin (TG), miconazole and SKF96365. When measured in Ca(2+)-free buffer, the ET-1-stimulated Ca(2+) transient decreased by 73% and the reintroduction of Ca(2+) induced a large sustained increase in [Ca(2+)](i). These effects were not affected by nifedipine, but were inhibited by miconazole and SKF96365-indicating that the sustained increase in [Ca(2+)](i) mediated by ET-1 was mostly due to capacitative Ca(2+) entry (CCE). The ET-1-induced CCE was inhibited by phorbol ester (PMA) but was enhanced by GF109203X; it was also enhanced by 8-bromo-cyclic AMP (8-Br-cAMP) but was inhibited by H89. Thus, protein kinase C (PKC) negatively regulated and cAMP-dependent protein kinase (PKA) positively regulated the ET-1-mediated CCE in these cells.
Ju
You Jing
YJ
Institute of Neuroscience, College of Life Science, National Yang Ming University, #155, Section 2, Li-Non Street, Shi-Pai, Taipei, Taiwan, ROC.
Wang
Chia-Mei
CM
Hung
Amos C
AC
Lo
Jun-Chih
JC
Lin
Hung-Jung
HJ
Sun
Synthia H
SH
D000598:Amino Acids, Cyclic / Q000378:metabolism; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D001921:Brain / Q000166:cytology; D002118:Calcium / Q000493:pharmacokinetics*; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology*; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D025802:Electric Capacitance; D019332:Endothelin-1 / Q000494:pharmacology*; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D010456:Peptides, Cyclic / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000378:metabolism*
D000598:Amino Acids, Cyclic; D000959:Antihypertensive Agents; D019332:Endothelin-1; D010456:Peptides, Cyclic; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C072247:cyclo(Trp-Asp-Pro-Val-Leu); D002118:Calcium