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Pharmacological profile of the ATP‐mediated increase in L‐type calcium current amplitude and activation of a non‐specific cationic current in rat ventricular cells
Author(s) -
Scamps Frédérique,
Vassort Guy
Publication year - 1994
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.1476-5381.1994.tb17089.x
Subject(s) - suramin , chemistry , adenosine triphosphate , potency , biophysics , purinergic receptor , beta (programming language) , biochemistry , biology , receptor , in vitro , computer science , programming language
1 The pharmacological profile of the ATP‐induced increase in I Ca amplitude and of ATP activation of a non‐specific cationic current, I ATP , was investigated in rat ventricular cells. 2 The EC 50 values for I Ca increase and I ATP activation were 0.36 μ m and 0.76 μ m respectively. Suramin (10 μ m ) and cibacron blue (1 μ m ) competitively antagonized both effects of ATP. 3 The rank order of efficacy and potency of ATP analogues in increasing I Ca amplitude was 2‐methylthio‐ATP ≅ ATP ≅ ATPγS. The derivatives α,β‐methylene‐ATP, β,γ‐methylene‐ATP and β,γ‐imido‐ATP up to 500 μ m had no significant effects. 4 The rank order of efficacy of ATP analogues in activating a non‐specific cationic current, I ATP , was 2‐methylthio‐ATP > ATP > > ATPγS. The rank order of potency was 2‐methylthio‐ATP ≅ ATP. The EC 50 of ATPγS could not be determined owing to its very low efficacy. 5 The ATP analogues α,β‐methylene‐ATP, β,γ‐methylene‐ATP and β,γ‐imido‐ATP at 500 μ m did not activate I ATP but acted as antagonists of activation of I ATP by ATP. 6 The results suggest that the increase in I Ca amplitude induced by external ATP is due to activation of P 2Y ‐purinoceptors. 7 The mechanism of I ATP activation remains to be determined before the receptor subtype involved can be deduced.