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Characterization of P 2 ‐purinoceptor mediated cyclic AMP formation in mouse C2C12 myotubes
Author(s) -
Henning Robert H.,
Duin Marry,
Hertog Adriaan,
Nelemans Adriaan
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.tb13782.x
Subject(s) - suramin , adenosine , adenosine monophosphate , adenosine triphosphate , atp hydrolysis , chemistry , nucleotide , medicine , endocrinology , biochemistry , biology , receptor , enzyme , atpase , gene
1 The formation of adenosine 3′:5′‐cyclic monophosphate (cyclic AMP) and inositol(1,4,5)trisphosphate (Ins(1,4,5)P 3 ), induced by ATP and other nucleotides was investigated in mouse C2C12 myotubes. 2 ATP (100 μ m ) and ATP7S (100 μ m ) caused a sustained increase in cyclic AMP content of the cells, reaching a maximum after 10 min. The cyclic AMP content reached a maximum in the presence of 100 μ m ATP, followed by a decline at higher ATP concentrations. ATP‐induced cyclic AMP formation was inhibited by the P 2 ‐purinoceptor antagonist, suramin. 3 Myotubes hydrolysed ATP to ADP at a rate of 9.7 ± 1.0 nmol mg −1 protein min −1 . However, further hydrolysis of ADP to AMP and adenosine was negligible. 4 The cyclic AMP formation induced by ADP (10 μ m –1 m m ) showed similar characteristics to that induced by ATP, but a less pronounced decline was observed than with ATP. ADP‐induced cyclic AMP formation was blocked by suramin, while cyclic AMP formation elicited by adenosine (10 μ m –1 m m ) was insensitive to suramin. 5 The ATP analogue, α,β‐methylene‐ATP also induced a suramin‐sensitive cyclic AMP formation, while 2‐methylthio‐ATP and the pyrimidine, UTP, did not affect cyclic AMP levels. 6 Stimulation of the myotubes with ATP or UTP (10 μ m –1 m m ) caused a concentration‐dependent increase in the Ins(1,4,5)P 3 content of the cells. ADP (100 μ m –1 m m ) was less effective. Adenosine did not affect Ins(1,4,5)P 3 levels. 7 Incubation of the cells with UTP (30 μ m –1 m m ) inhibited the ATP‐ and ADP‐induced cyclic AMP formation, suggesting that stimulation of the ‘nucleotide’ type P 2 ‐receptor inhibits P 2 ‐purinoceptor mediated cyclic AMP formation in C2C12 myotubes. In contrast, UTP (30 μ m –1 m m ) enhanced adenosine‐induced cyclic AMP formation. 8 Adenosine‐sensitive P 1 ‐purinoceptors activating cyclic AMP formation were found in C2C12 myotubes. Further, a novel P 2 ‐purinoceptor is postulated, sensitive to ATP, ADP and ATPγS, which also activates the formation of cyclic AMP in C2C12 myotubes.