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Titolo:
VOLTAGE-DEPENDENT POTASSIUM CURRENTS IN OVINE SOMATOTROPHS AND THEIR FUNCTION IN GROWTH-HORMONE SECRETION
Autore:
CHEN C; HEYWARD P; ZHANG J; WU DX; CLARKE IJ;
Indirizzi:
PRINCE HENRYS INST MED RES,POB 152 CLAYTON VIC 3168 AUSTRALIA
Titolo Testata:
Neuroendocrinology
fascicolo: 1, volume: 59, anno: 1994,
pagine: 1 - 9
SICI:
0028-3835(1994)59:1<1:VPCIOS>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
THYROTROPIN-RELEASING-HORMONE; ANTERIOR-PITUITARY CELLS; LOCUS COERULEUS NEURONS; RAT SOMATOTROPHS; ELECTROPHYSIOLOGICAL RESPONSES; MEMBRANE CURRENTS; SMALL CONDUCTANCE; LACTOTROPH CELLS; PRIMARY CULTURE; K+ CHANNELS;
Keywords:
K+ CURRENTS; PATCH CLAMP; SOMATOTROPHS; CA2+; GROWTH HORMONE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
34
Recensione:
Indirizzi per estratti:
Citazione:
C. Chen et al., "VOLTAGE-DEPENDENT POTASSIUM CURRENTS IN OVINE SOMATOTROPHS AND THEIR FUNCTION IN GROWTH-HORMONE SECRETION", Neuroendocrinology, 59(1), 1994, pp. 1-9

Abstract

Sheep somatotroph-enriched cultures were obtained by means of enzyme dissociation and Percoll gradient separation. Nystatin-perforated-whole-cell recordings were performed on post-recording-identified somatotrophs after 4-14 days in vitro. Using Ca2+-free, tetrodotoxin-containing (1 mu M) bath solution and K+ electrode solution, three types of voltage-dependent K+ currents were recorded as inward rectifying, outwardtransient and outward delayed rectifying K+ currents. The inward rectifying K+ current was very small at physiological extracellular K+ concentrations (5 mM) and enhanced by increasing the K+ concentration in the bath to 55 mM; it was blocked by tetraethylammonium (2 mM) but notby 4-aminopyridine (5 mM). A transient outward K+ current appeared at-50 mV and was selectively diminished by dr-aminopyridine (2 or 4 mM). A delayed rectifying outward K+ current was observed when the membrane potential was depolarized to -20 mV and was blocked by tetraethylammonium (2 mM) but not LF-aminopyridine (4 mM). Application of 4-aminopyridine but not tetraethylammonium (up to 5 mM) depolarized the cell membrane potential recorded under current clamp conditions and triggered action potentials when the bath solution contained Ca2+ (2 mM) but not tetrodotoxin. The intracellular Ca2+ concentration was increased by4-aminopyridine as was growth hormone release. Therefore, the 4-aminopyridine-sensitive transient outward Kt current appears to be important in the determining the resting potential of ovine somatotrophs and plays a major role in regulating basal intracellular Ca2+ concentrationand growth hormone secretion.

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Documento generato il 25/01/20 alle ore 19:47:29