Calcium signalling through nucleotide receptor P2X1 in rat portal vein myocytes.
J Physiol
; 536(Pt 2): 339-50, 2001 Oct 15.
Article
em En
| MEDLINE
| ID: mdl-11600670
ABSTRACT
1. ATP-mediated Ca2+ signalling was studied in freshly isolated rat portal vein myocytes by means of a laser confocal microscope and the patch-clamp technique. 2. In vascular myocytes held at -60 mV, ATP induced a large inward current that was supported mainly by activation of P2X1 receptors, although other P2X receptor subtypes (P2X3, P2X4 and P2X5) were revealed by reverse transcription-polymerase chain reaction. 3. Confocal Ca2+ measurements revealed that ATP-mediated Ca2+ responses started at initiation sites where spontaneous or triggered Ca2+ sparks were not detected, whereas membrane depolarizations triggered Ca2+ waves by repetitive activation of Ca2+ sparks from a single initiation site. 4. ATP-mediated Ca2+ responses depended on Ca2+ influx through non-selective cation channels that activated, in turn, Ca2+ release from the intracellular store via ryanodine receptors (RYRs). Using specific antibodies directed against the RYR subtypes, we show that ATP-mediated Ca2+ release requires, at least, RYR2, but not RYR3. 5. Our results suggest that, in vascular myocytes, Ca2+ influx through P2X1 receptors may trigger Ca2+-induced Ca2+ release at intracellular sites where RYRs are not clustered.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Veia Porta
/
Trifosfato de Adenosina
/
Receptores Purinérgicos P2
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Sinalização do Cálcio
/
Músculo Liso Vascular
Limite:
Animals
Idioma:
En
Revista:
J Physiol
Ano de publicação:
2001
Tipo de documento:
Article