The neurotransmitter(s) that generates the fast component of the inhibitory junction potential (IJP-F) in human jejunal circular smooth muscle is not known. The aim of this study was to determine the role of ATP and purinergic receptors in the generation of the IJP-F in human jejunal circular smooth muscle strips. The P2-receptor antagonist suramin (100 μM) reduced the IJP-F by 28%. Apamin (1 μM) reduced the IJP-F by 25%. Desensitization of muscle strips with the putative P(2x)-receptor agonist α,β-methylene ATP (α,β-MeATP, 100 μM) decreased the IJP-F by 44%, and desensitization with the putative P(2y)-receptor agonist adenosine 5'-O-2-thiodiphosphate (ADPβS) completely abolished the IJP-F. Desensitization with the putative P(2y)- receptor agonist 2-methylthioATP had no effect on the IJP-F. Exogenous ATP evoked a hyperpolarization with a time course that matched the IJP-F. The ATP-evoked hyperpolarization was reduced by apamin and suramin, reduced by desensitization with α,β-MeATP (69% decrease), and abolished by desensitization with ADPβS. These data suggest that the IJP-F in human jejunal circular smooth muscle is mediated in part by ATP through an ADPβS- sensitive P2 receptor.
|Original language||English (US)|
|Journal||American Journal of Physiology - Gastrointestinal and Liver Physiology|
|Issue number||6 39-6|
|State||Published - Jun 1999|
- Purinergic receptors
ASJC Scopus subject areas
- Physiology (medical)