Purinergic receptors coupled to intracellular Ca2+ signals and exocytosis in rat prostate neuroendocrine cells.
Rat prostate neuroendocrine cells (RPNECs) display a variety of ion channels and exhibit alpha-adrenergic regulation of cytosolic Ca(2+) concentration ([Ca(2+)])(c). In this study, purinergic regulation of [Ca(2+)](c) and exocytosis was investigated in freshly isolated single RPNECs showing chromogranin A immunoreactivity. The presence of P2X and P2Y receptors in RPNECs was verified by the transient activation of Ca(2+)-permeable cationic channels and the release of Ca(2+) from intracellular stores by extracellular ATP, respectively. The transient inward cationic current was effectively activated by alpha,beta-methyleneadenosine 5'-triphosphate (alpha,beta-MeATP) and blocked by 2',3'-O-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate, suggesting the presence of a P2X(1) or P2X(3) subtype. For the release of stored Ca(2+), ATP and UTP were equally potent, indicating the functional expression of the P2Y(2) or P2Y(4) subtype. The mRNAs for P2X(1) and P2Y(2) were confirmed from reverse transcription-PCR analysis of RPNECs. The application of alpha,beta-MeATP induced large and transient increases in [Ca(2+)](c), which were not attenuated by the blockers of voltage-activated Ca(2+) channels or by depleting intracellular Ca(2+) stores, but were abolished by omitting extracellular Ca(2+). The application of UTP increased [Ca(2+)](c) to 55% of the peak Delta[Ca(2+)](c) induced by alpha,beta-MeATP. The application of alpha,beta-MeATP induced exocytotic responses of RPNECs as monitored by carbon fiber amperometry and capacitance measurements. To our interest, the application of UTP did not induce amperometric currents, but reduced the membrane capacitance, indicating a net endocytosis. From these results, we postulate that a sharp rise in [Ca(2+)](c) by the P2X-mediated Ca(2+) influx is required for exocytosis, whereas the relatively slow release of stored Ca(2+) induces endocytosis in RPNECs.
Kim
Jun Hee
JH
Department of Physiology and Center for Molecular Medicine, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea.
Nam
Joo Hyun
JH
Kim
Mean-Hwan
MH
Koh
Duk-Su
DS
Choi
So-Jung
SJ
Kim
Soo Jeong
SJ
Lee
Ji Eun
JE
Min
Kyeong Min
KM
Uhm
Dae-Yong
DY
Kim
Sung Joon
SJ
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D025802:Electric Capacitance; D004594:Electrophysiology / Q000379:methods; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008856:Microscopy, Fluorescence; D009490:Neurosecretory Systems / Q000166:cytology / Q000378:metabolism*; D011467:Prostate / Q000166:cytology / Q000378:metabolism*; D058910:Purinergic P2 Receptor Agonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism*; D013498:Suramin / Q000494:pharmacology; D014530:Uridine Diphosphate / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000494:pharmacology
D058910:Purinergic P2 Receptor Agonists; D018048:Receptors, Purinergic P2; C022571:adenosine 5'-O-(3-thiotriphosphate); D014530:Uridine Diphosphate; D013498:Suramin; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D002118:Calcium; D014544:Uridine Triphosphate