Fig. 4.

Inhibitory junction potentials (IJPs) evoked in the circular muscle coat by focal electrical stimulation of intraganglionic fiber tracts in the myenteric division of the enteric nervous system in human jejunal preparations. A₁: control IJP consisting of a rapidly activating component followed by a slowly activating component. A₂: suppression of the IJP by the P2Y₁ receptor agonist MRS 2365 due to hyperpolarization of the membrane potential by MRS 2365 and movement of the membrane potential closer to the equilibrium potential for the IJP. A₃: suppression of the IJP evoked at the resting membrane potential by β-NAD. B₁: suppression of the IJP by the P2Y₁ receptor antagonist MRS 2179. B₂: suppression of the IJP by the P2Y₁ receptor antagonist MRS 2500. B₃: suppression of the IJP by a high concentration of β-NAD. C₁: suppression of the IJP by the high concentration of β-NAD was reversed by preincubation with the adenosine A₁ receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). C₂: suppression of the IJP by adenosine. C₃: final washout. Preparations were washed between application of each agent or combination of agents.