Calcium signalling through nucleotide receptor P2X1 in rat portal vein myocytes

J Mironneau; F Coussin; J L Morel; C Barbot; L H Jeyakumar; S Fleischer; C Mironneau

doi:10.1111/j.1469-7793.2001.0339c.xd

Calcium signalling through nucleotide receptor P2X1 in rat portal vein myocytes

J Physiol. 2001 Oct 15;536(Pt 2):339-50. doi: 10.1111/j.1469-7793.2001.0339c.xd.

Authors

J Mironneau¹, F Coussin, J L Morel, C Barbot, L H Jeyakumar, S Fleischer, C Mironneau

Affiliation

¹ Laboratoire de Signalisation et Interactions Cellulaires, CNRS UMR 5017, Université de Bordeaux 2, 146 rue Léo Saignat, Bordeaux Cedex 33076, France. jean.mironneau@umr5017.u-bordeaux2.fr

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.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / pharmacology
Adenosine Triphosphate / analogs & derivatives*
Adenosine Triphosphate / pharmacology
Animals
Antibodies / pharmacology
Calcium / metabolism
Calcium Channel Agonists / pharmacology
Calcium Channels / immunology
Calcium Signaling / physiology*
Gene Expression / physiology
Inositol 1,4,5-Trisphosphate Receptors
Membrane Potentials / drug effects
Membrane Potentials / physiology
Muscle, Smooth, Vascular / chemistry
Muscle, Smooth, Vascular / cytology
Muscle, Smooth, Vascular / physiology*
Patch-Clamp Techniques
Portal Vein / cytology*
Rats
Receptors, Cytoplasmic and Nuclear / immunology
Receptors, Purinergic P2 / analysis
Receptors, Purinergic P2 / genetics
Receptors, Purinergic P2 / metabolism*
Receptors, Purinergic P2X
Ryanodine Receptor Calcium Release Channel / immunology
Uridine Triphosphate / pharmacology

Substances

Antibodies
Calcium Channel Agonists
Calcium Channels
Inositol 1,4,5-Trisphosphate Receptors
Receptors, Cytoplasmic and Nuclear
Receptors, Purinergic P2
Receptors, Purinergic P2X
Ryanodine Receptor Calcium Release Channel
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
Adenosine Triphosphate
alpha,beta-methyleneadenosine 5'-triphosphate
Calcium
Uridine Triphosphate