P2-purinoreceptor evoked changes in intracellular calcium oscillations in single isolated human granulosa-lutein cells.
In this study, we have demonstrated that P2-purinoreceptor agonists evoke oscillatory intracellular calcium ([Ca2+]i) responses in human granulosa-lutein cells (GLCs). Intracellular calcium was measured using microspectrofluorimetric techniques. ATP at concentrations of 1-100 microM increased [Ca2+]i, whereas neither adenosine nor AMP evoked changes in [Ca2+]i. The nonhydrolysable ATP analogue, ATP gamma S, also elevated [Ca2+]i with an efficacy similar to that of ATP, indicating that the changes in Ca2+ were not due to ATP hydrolysis, but that human GLCs possess functional P2-purinoreceptors. Uridine triphosphate (UTP) was equipotent to ATP at stimulating [Ca2+]i, and both ATP and UTP were consistently more effective at eliciting a response than ADP, suggesting that human GLCs possess the P2U class of purinergic receptors (ATP = UTP > > ADP > > AMP = adenosine). We have demonstrated that the purinergic agonist-induced changes in [Ca2+]i involve both Ca2+ influx and Ca2+ mobilization from cytosolic stores. Prolonged ATP treatment in Ca(2+)-free buffer (1 mM EGTA) still evokes transient oscillatory changes in [Ca2+]i in a pertussis toxin-insensitive manner. In Ca(2+)-containing conditions, the sustained phase of the response was generally unaffected by verapamil (10 microM), suggesting that influx is not occurring through voltage-dependent Ca(2+)-channels. These findings are consistent with the hypothesis that ATP and other P2-purinergic receptor agonists elicit changes in [Ca2+]i in human ovarian cells and that these events are initiated by the release of Ca2+ from cytosolic stores, and sustained by extracellular calcium ([Ca2+]e) influx. This is the first time that oscillatory patterns of [Ca2+]i have been reported in human GLCs.
Lee
P S
PS
Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, Canada.
Squires
P E
PE
Buchan
A M
AM
Yuen
B H
BH
Leung
P C
PC
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002469:Cell Separation; D003338:Corpus Luteum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D009994:Osmolar Concentration; D058913:Purinergic Agonists; D011983:Receptors, Purinergic / Q000502:physiology*
D058913:Purinergic Agonists; D011983:Receptors, Purinergic; C022571:adenosine 5'-O-(3-thiotriphosphate); D000255:Adenosine Triphosphate; D002118:Calcium