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Titolo:
Ca2+-dependent K+ current and exocytosis in responses to caffeine and muscarine in voltage-clamped guinea-pig adrenal chromaffin cells
Autore:
Ohta, T; Wakade, AR; Nakazato, Y; Ito, S;
Indirizzi:
Hokkaido Univ, Grad Sch Vet Med, Dept Biomed Sci, Pharmacol Lab, Sapporo, Hokkaido 0600818, Japan Hokkaido Univ Sapporo Hokkaido Japan 0600818 oro, Hokkaido 0600818, Japan Wayne State Univ, Sch Med, Dept Pharmacol, Detroit, MI 48201 USA Wayne State Univ Detroit MI USA 48201 pt Pharmacol, Detroit, MI 48201 USA
Titolo Testata:
JOURNAL OF NEUROCHEMISTRY
fascicolo: 6, volume: 78, anno: 2001,
pagine: 1243 - 1255
SICI:
0022-3042(200109)78:6<1243:CKCAEI>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
CYCLASE-ACTIVATING POLYPEPTIDE; SENSITIVE CA2+ STORES; PROTEIN-KINASE-C; CATECHOLAMINE SECRETION; INTRACELLULAR STORES; RECEPTOR ACTIVATION; POTASSIUM CHANNELS; CALCIUM; RELEASE; TRANSMITTER;
Keywords:
amperometry; Ca2+ -dependent K+ channels; caffeine; chromaffin cells; whole-cell voltage-clamp.;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
41
Recensione:
Indirizzi per estratti:
Indirizzo: Ohta, T Hokkaido Univ, Grad Sch Vet Med, Dept Biomed Sci, Pharmacol Lab, Sapporo, Hokkaido 0600818, Japan Hokkaido Univ Sapporo Hokkaido Japan 0600818 kaido 0600818, Japan
Citazione:
T. Ohta et al., "Ca2+-dependent K+ current and exocytosis in responses to caffeine and muscarine in voltage-clamped guinea-pig adrenal chromaffin cells", J NEUROCHEM, 78(6), 2001, pp. 1243-1255

Abstract

We characterized changes in membrane currents and the cytosolic Ca2+ concentration, [Ca2+](i), in response to caffeine, and compared them with those in response to muscarine using the perforated patch-clamp technique and fura-2 microfluorimetry in guinea-pig adrenal chromaffin cells. Catecholamine release from single voltage-clamped cells was monitored with amperometry using carbon microelectrodes. Caffeine produced a transient outward current (I-out) at holding potentials over -60 mV, increasing in amplitude with increasing the potentials. It also evoked a rapid increase of [Ca2+](i) at all potentials examined. The current-voltage relation revealed that the activation of K+ channels was responsible for the I-out evoked by caffeine. Both current and [Ca2+](i) responses were reversibly abolished by cyclopiazonic acid, an inhibitor of Ca2+-pump ATPase. At -30 mV, the caffeine-induced I-out, but not [Ca2+](i), was partly inhibited by either charybdotoxin or apamin. In the majority of cells tested, caffeine induced a larger I-out but a smaller [Ca2+](i) increase than muscarine. Caffeine and muscarine increased catecholamine release from voltage-clamped single cells concomitant with the transient increase of [Ca2+](i), and there was a positive correlation between them. These results indicate that caffeine activates Ca2+-dependent Kchannels and catecholamine secretion due to the release of Ca2+ from internal stores in voltage-clamped adrenal chromaffin cells of the guinea-pig. There seems to be a spatial difference between [Ca2+](i) increased by Ca2+ release from caffeine-sensitive stores and that released from muscarine (inositol 1,4,5-trisphosphate)-sensitive ones.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 10/04/20 alle ore 15:50:07