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Effects of ATP on cultured smooth muscle cells from rat aorta
Author(s) -
Weid P.Y.,
Serebryakov V.N.,
Orallo F.,
Bergmann C.,
Snetkov V.A.,
Takeda K.
Publication year - 1993
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1993.tb12854.x
Subject(s) - biophysics , suramin , pipette , reversal potential , membrane potential , patch clamp , adenosine triphosphate , chemistry , adenosine , electrophysiology , voltage clamp , purinergic receptor , biochemistry , biology , neuroscience , in vitro , receptor
1 Membrane ionic currents provoked by externally applied ATP were studied by patch‐clamp techniques in cultured aortic smooth muscle cells of the rat. 2 Using standard bath and pipette solutions and whole‐cell voltage‐clamp, ATP evoked an inward current when the cell membrane potential was held at −50 mV and an outward current when the potential was held at 30 mV, with a reversal potential near −10 mV. 3 Application of ATPγS gave results similar to those obtained with ATP, while adenosine, AMP and α,β‐methylene ATP were ineffective. The ATP‐activated current was inhibited by suramin, 100 μ m . 4 ATP also induced a biphasic rise in internal free Ca levels as shown directly by Fura‐2 measurements and by the increase in Ca‐dependent K single‐channel activity in cell‐attached patches. 5 With outward current through K channels blocked by internal Cs and TEA, modification of the ionic composition of bath and pipette solutions revealed that the reversal potential for the ATP‐induced whole‐cell current closely followed E Cl , the chloride equilibrium potential, and was insensitive to manipulations of the monovalent cation gradient. 6 These results indicate that in rat cultured aortic smooth muscle cells, ATP binding to P 2 ‐purinoceptors produces increases of internal free Ca levels and subsequent activation of both Ca‐dependent K and Cl currents.