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Titolo:
CONVERGENT AND PARALLEL ACTIVATION OF LOW-CONDUCTANCE POTASSIUM CHANNELS BY CALCIUM AND CAMP-DEPENDENT PROTEIN-KINASE
Autore:
LIDOFSKY SD;
Indirizzi:
UNIV CALIF SAN FRANCISCO,DEPT MED SAN FRANCISCO CA 94143 UNIV CALIF SAN FRANCISCO,CTR LIVER SAN FRANCISCO CA 94143
Titolo Testata:
Proceedings of the National Academy of Sciences of the United Statesof America
fascicolo: 15, volume: 92, anno: 1995,
pagine: 7115 - 7119
SICI:
0027-8424(1995)92:15<7115:CAPAOL>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
CYCLIC-AMP; K+ CHANNELS; RAT HEPATOCYTES; GUINEA-PIG; ADRENERGIC RESPONSES; POTENTIAL DIFFERENCE; CA-2+ INFLUX; CELLS; LIVER; MEMBRANE;
Keywords:
LIVER CELLS; PATCH CLAMP; SIGNAL TRANSDUCTION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
37
Recensione:
Indirizzi per estratti:
Citazione:
S.D. Lidofsky, "CONVERGENT AND PARALLEL ACTIVATION OF LOW-CONDUCTANCE POTASSIUM CHANNELS BY CALCIUM AND CAMP-DEPENDENT PROTEIN-KINASE", Proceedings of the National Academy of Sciences of the United Statesof America, 92(15), 1995, pp. 7115-7119

Abstract

K+ channels, which have been linked to regulation of electrogenic solute transport as well as Ca2+ influx, represent a locus in hepatocytesfor the concerted actions of hormones that employ Ca2+ and cAMP as intracellular messengers, Despite considerable study, the single-channelbasis for synergistic effects of Ca2+ and cAMP on hepatocellular K+ conductance is not well understood. To address this question, patch-clamp recording techniques were applied to a model liver cell line, HTC hepatoma cells. Increasing the cytosolic Ca2+ concentration ([Ca2+](i))in ETC cells, either by activation of purinergic receptors with ATP or by inhibition of intracellular Ca2+ sequestration with thapsigargin,activated low-conductance (9-pS) K+ channels. Studies with excised membrane patches suggested that these channels were directly activated by Ca2+. Exposure of HTC cells to a permeant cAMP analog, 8-(4-chlorophenylthio)-cAMP, also activated 9-pS K+ channels but did not change [Ca2+](i). In excised membrane patches, cAMP-dependent protein kinase (the downstream effector of cAMP) activated K+ channels with conductance and selectivity identical to those of channels activated by Ca2+. In addition, cAMP-dependent protein kinase activated a distinct K+ channeltype (5 pS). These data represent the differential regulation of low-conductance Kf channels by signaling pathways mediated by Ca2+ and cAMP. Moreover, since low-conductance Ca2+-activated Kf channels have been identified in a variety of cell types, these findings suggest that differential regulation of K+ channels by hormones with distinct signaling pathways may provide a mechanism for hormonal control of solute transport and Ca2+-dependent cellular functions in the liver as well as other nonexcitable tissues.

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Documento generato il 23/09/20 alle ore 09:35:35