Lack of run-down of smooth muscle P2X receptor currents recorded with the amphotericin permeabilized patch technique, physiological and pharmacological characterization of the properties of mesenteric artery P2X receptor ion channels

Autor: C J Lewis, Richard J. Evans
Rok vydání: 2000
Předmět:
Male
P2Y receptor
Cell Membrane Permeability
Patch-Clamp Techniques
Time Factors
Ion Channels
Muscle
Smooth
Vascular
Membrane Potentials
Purinergic Agonists
chemistry.chemical_compound
Adenosine Triphosphate
heterocyclic compounds
Receptor
Mesenteric arteries
musculoskeletal
neural
and ocular physiology
Immunohistochemistry
Mesenteric Arteries
medicine.anatomical_structure
Receptors
Purinergic P2X
Pyridoxal Phosphate
Papers
Guanosine Triphosphate
Agonist
endocrine system
medicine.medical_specialty
medicine.drug_class
Suramin
P2 receptor
Biology
Amphotericin B
Internal medicine
medicine
Animals
PPADS
Patch clamp
Rats
Wistar
Pharmacology
Dose-Response Relationship
Drug
Receptors
Purinergic P2
urogenital system
Thionucleotides
Rats
Endocrinology
chemistry
Biophysics
Calcium
Receptors
Purinergic P2X7
Receptors
Purinergic P2X5
Receptors
Purinergic P2X4
Receptors
Purinergic P2X3
Receptors
Purinergic P2X2
Zdroj: British Journal of Pharmacology. 131:1659-1666
ISSN: 0007-1188
Popis: Immunoreactivity for P2X(1), P2X(4) and P2X(5) receptor subtypes was detected in the smooth muscle cell layer of second and third order rat mesenteric arteries immunoreactivity, for P2X(2), P2X(3), P2X(6) and P2X(7) receptors was below the level of detection in the smooth muscle layer. P2X receptor-mediated currents were recorded in patch clamp studies on acutely dissociated mesenteric artery smooth muscle cells. Purinergic agonists evoked transient inward currents that decayed rapidly in the continued presence of agonist (tau approximately 200 ms). Standard whole cell responses to repeated applications of agonist at 5 min intervals ran down. Run-down was unaffected by changes in extracellular calcium concentration, intracellular calcium buffering or the inclusion of ATP and GTP in the pipette solution. Run-down was overcome and reproducible responses to purinergic agonists were recorded using the amphotericin permeabilized patch recording configuration. The rank order of potency at the P2X receptor was ATP=2 methylthio ATP>alpha, beta-methylene ATP>CTP=l-beta,gamma-methylene ATP. Only ATP and 2meSATP were full agonists. The P2 receptor antagonists suramin and PPADS inhibited P2X receptor-mediated currents with IC(50)s of 4 microM and 70 nM respectively. These results provide further characterization of artery P2X receptors and demonstrate that the properties are dominated by a P2X(1)-like receptor phenotype. No evidence could be found for a phenotype corresponding to homomeric P2X(4) or P2X(5) receptors or to heteromeric P2X(1/5) receptors and the functional role of these receptors in arteries remains unclear.
Databáze: OpenAIRE
Externí odkaz: