Voltage-dependent ion channel currents in putative neuroendocrine cells dissociated from the ventral prostate of rat.
Prostate neuroendocrine (NE) cells play important roles in the growth and differentiation of the prostate. Following enzymatic digestion of rat ventral prostate, the whole-cell patch-clamp technique was applied to dark, round cells that exhibited chromogranin-A immunoreactivity, a representative marker of NE cells. Under zero current-clamp conditions, putative NE cells showed hyperpolarized resting membrane potentials of some -70 mV, and spontaneous action potentials were induced by an increase in external [K+] or by the injection of current. Using a CsCl pipette solution, step-like depolarization activated high-voltage-activated Ca2+ current (HVA I(Ca)) and tetrodotoxin-resistant voltage-activated Na+ current. The HVA I(Ca) was blocked by nifedipine and omega-conotoxin GVIA, L-type and N-type Ca2+ channel blockers, respectively. Using a KCl pipette solution, the transient outward K+ current (I(to)), Ca2+ -activated K+ currents (I(K,Ca)), the non-inactivating outward current and an inwardly rectifying K+ current (I(Kir)) were identified. I(K,Ca) was suppressed by charybdotoxin (50 nM), iberiotoxin (10 nM) or clotrimazol (1 microM), but not by apamine (100 nM). I(to) was inhibited by 4-aminopyridine (5 mM). I(Kir) was identified as a Ba2+ -sensitive inwardly rectifying current in the presence of a high-K+ bath solution. The voltage- and Ca2+ -activated ion channels could play significant roles in the regulation of neurohormonal secretion in the prostate.
Kim
Jun Hee
JH
Department of Physiology Sungkyunkwan University School of Medicine, 440-746, Suwon, Korea.
Shin
Sun Young
SY
Yun
Sang Soon
SS
Kim
Tae Jin
TJ
Oh
Seung-June
SJ
Kim
Kwang Myung
KM
Chung
Young-Shin
YS
Hong
Eun-Kyoung
EK
Uhm
Dae-Yong
DY
Kim
Sung Joon
SJ
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D018999:Charybdotoxin / Q000494:pharmacology; D053379:Chromogranin A; D002864:Chromogranins; D004553:Electric Conductivity; D005455:Fluorescent Antibody Technique; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009490:Neurosecretory Systems / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011467:Prostate / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
D002121:Calcium Channel Blockers; D053379:Chromogranin A; D002864:Chromogranins; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D015222:Sodium Channels; D018999:Charybdotoxin; D013779:Tetrodotoxin; D011188:Potassium