Interplay between Ca2+ release and Ca2+ influx underlies localized hyperpolarization-induced [Ca2+]i waves in prostatic cells.
Calcium seems to be a major second messenger involved in the regulation of prostatic cell functions, but the mechanisms underlying its control are poorly understood. We investigated spatiotemporal aspects of Ca2+ signals in the LNCaP cell line, a model of androgen-dependent prostatic cells, by using non-invasive external electric field pulses that hyperpolarize the anode facing membrane and depolarize the membrane facing the cathode. Using high-speed fluo-3 confocal imaging, we found that an electric field pulse (10-15 V/cm, 1-5 mA, 5 ms) initiated rapidly, at the hyperpolarized end of the cell, a propagated [Ca2+]i wave which spread through the cell with a constant amplitude and an average velocity of about 20 microns/s. As evidenced by the total wave inhibition either by the block of Ca2+ entry or the depletion of Ca2+ stores by thapsigargin, a specific Ca(2+)-ATPase inhibitor, the [Ca2+]i wave initiation may imply a localized Ca2+ influx linked to a focal auto-regenerative process of Ca2+ release. Using different external Ca2+ and Ca2+ entry blockers concentrations, Mn2+ quenching of fluo-3 and fura-2 fluorescence and inhibitors of InsP3 production, we found evidence that the [Ca2+]i wave progression required, in the presence of basal levels of InsP3, an interplay between Ca2+ release from InsP3-sensitive Ca2+ stores and Ca2+ influx through channels possibly activated by the [Ca2+]i rise.
Perret
S
S
Laboratoire de Neurophysiologie, CNRS UMR 5543, Université Victor Segalen-Bordeaux, France.
Cantereau
A
A
Audin
J
J
Dufy
B
B
Georgescauld
D
D
D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D016764:Cell Polarity; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016257:Fura-2 / Q000032:analysis; D005682:Gadolinium / Q000494:pharmacology; D006801:Humans; D007811:Lanthanum / Q000494:pharmacology; D008297:Male; D008345:Manganese / Q000378:metabolism; D018613:Microscopy, Confocal; D009553:Nimodipine / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D012433:Ryanodine / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D012433:Ryanodine; D008345:Manganese; D009553:Nimodipine; D019284:Thapsigargin; D007811:Lanthanum; D005682:Gadolinium; D002118:Calcium; D016257:Fura-2