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. 1995 May;115(1):177–185. doi: 10.1111/j.1476-5381.1995.tb16336.x

A study on P2X purinoceptors mediating the electrophysiological and contractile effects of purine nucleotides in rat vas deferens.

B S Khakh 1, A Surprenant 1, P P Humphrey 1
PMCID: PMC1908757  PMID: 7647973

Abstract

1. We have studied both the electrophysiological and contractile effects of the purine nucleotide, adenosine-5'-triphosphate (ATP), as well as a number of its structural analogues as agonists at P2X purinoceptors in the rat vas deferens in vitro. 2. Electrophysiological effects were investigated by a whole cell voltage clamp technique (holding potential-70 mV) with fast flow concentration-clamp applications of agonists in single isolated smooth muscle cells. ATP, 2-methylthio adenosine-5'-triphosphate (2-MeSATP) and alpha,beta methylene adenosine-5'-triphosphate (alpha,beta-meATP) all evoked inward currents over a similar concentration range (0.3-10 microM), being approximately equipotent with similar concentrations for threshold effects (0.3 microM). ADP (10 microM) also evoked a rapid current of similar peak amplitude to that seen with ATP (10 microM). 3. alpha,beta-meATP was the most potent agonist in producing concentrations of the rat vas deferens whole tissue preparation, with a threshold concentration equal to that in the electrophysiological studies (0.3 microM). However, ATP and 2-MeSATP were at least ten times less potent in studies measuring contraction than in the electrophysiological studies. Furthermore, their concentration-effect curves were shallow with smaller maximal responses than could be achieved with alpha,beta-meATP. ADP, AMP and adenosine were inactive at concentrations up to 1 mM. The rank order of agonist potencies observed for contraction was alpha,beta-meATP >> ATP = 2-MeSATP.(ABSTRACT TRUNCATED AT 250 WORDS)

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Selected References

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