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Titolo:
Multiple intracellular signallings involved in regulation of ion channels by GH releasing or inhibitory hormones in pituitary somatotropes
Autore:
Chen, C;
Indirizzi:
Prince Henrys Inst Med Res, Clayton, Vic 3168, Australia Prince Henrys Inst Med Res Clayton Vic Australia 3168 Vic 3168, Australia
Titolo Testata:
PROGRESS IN NATURAL SCIENCE
fascicolo: 3, volume: 11, anno: 2001,
pagine: 161 - 172
SICI:
1002-0071(200103)11:3<161:MISIIR>2.0.ZU;2-Y
Fonte:
ISI
Lingua:
ENG
Soggetto:
DEPENDENT POTASSIUM CURRENTS; CULTURED OVINE SOMATOTROPHS; RAT SOMATOTROPHS; CALCIUM CURRENTS; ELECTROPHYSIOLOGICAL RESPONSES; ADENOMA CELLS; SOMATOSTATIN; PROTEIN; SECRETION; K+;
Keywords:
GHRH; somatostatin; G protein; cAMP; protein kinases;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
28
Recensione:
Indirizzi per estratti:
Indirizzo: Chen, C Prince Henrys Inst Med Res, POB 5152, Clayton, Vic 3168, AustraliaPrince Henrys Inst Med Res POB 5152 Clayton Vic Australia 3168 lia
Citazione:
C. Chen, "Multiple intracellular signallings involved in regulation of ion channels by GH releasing or inhibitory hormones in pituitary somatotropes", PROG NAT SC, 11(3), 2001, pp. 161-172

Abstract

Influx of Ca2+ via Ca2+ channels is the major step triggering exocytosis of pituitary somatotropes to release growth hormone (GH). Voltage-gated Ca2and K+ channels, the primary determinants of the influx of Ca2+ in somatotropes, are regulated by CII-releasing hormone (GHRH) and somatostatin (SRIF) through G protein-coupled signalling systems. Using whole-cell patch-clamp techniques, the changes of the Ca2+ and K+ currents in primary cultured somatotropes were recorded and signalling systems were studied using pharmacological reagents and intracellular dialysis of non-permeable molecules including antibodies and antisense oligonucleotides. GHRH increased both L-andT-types Ca2+ currents and decreased transient (I-A) and delayed rectified (I-K) K+ currents. The increase in Ca2+ currents by GHRH was mediated by cAMP/protein kinase A system but the decrease in K+ currents required normal function of protein kinase C system. The GHRH-induced alteration of Ca2+ and K+ currents augments the influx of Ca2+, leading to an increase in the [Ca2+]i and the GN secretion. In contrary, a significant reduction in Ca2+ currents and increase in K+ currents were obtained in response to SRIF. The ion channel response to SRIF was demonstrated as a membrane delimited pathway acid can be recorded by classic whole-cell configuration. Intracellular dialysis of anti-alphai(3) antibodies attenuated the increase in K+ currentsby SRIF whereas anti-ao antibodies blocked the reduction in the Ca2+ current by SRIF. Dialysis of antisense oligonucleotides specific for alphao(2) sub-units also attenuated the inhibition of SRIF on the Ca2+ current. The Gi(3) protein mediated the increase in K+ currents and the Go(2) protein mediated the reduction in the Ca2+ current by SRIF. The SRIF-induced alterationof Ca2+ and K+ currents diminished the influx. of Ca2+, leading to a decrease in the [Ca2+]i and the GH secretion. It is therefore concluded that multiple signalling systems are employed in the ion channel response to GHRH or SRIF in somatotropes, which leads to an increase or decrease in the GH secretion.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 05/07/20 alle ore 12:19:19