Fig. 1.

EFS-evoked release of purines upon pharmacological inhibition or stimulation of nitric oxide signaling in human colon. A: chromatograms of tissue superfusates collected during EFS of colon muscularis in the absence of drugs (control) or in the presence of l-NNA (100 μM for 60 min), ODQ (10 μM for 30 min), or SNAP (1 μM for 5 min). Inhibition of NOS with l-NNA or of soluble guanylyl cyclase with ODQ increased the EFS-evoked release of purines whereas the NO donor, SNAP, reduced the EFS-evoked release of purines. Note that the peaks of Up4A are not clearly visible in the chromatograms at the scale shown. ADO, adenosine. Inset: comparison of fluorescence of ATP and NAD⁺; NAD⁺, 0.5 pmol, generates ~10 times lower fluorescent signal than 0.5 pmol ATP. LU, luminescence units. B: averaged data (means ± SE) summarizing the EFS-evoked release of NAD⁺/ADPR, ATP, and total purines (i.e., ATP+ADP+NAD⁺/ADPR+AMP+ADO) in human colon in the absence (Ctr, control) and presence of SNAP, l-NNA, and ODQ. Release in femtomoles per milligram of tissue (fmol/mg) is calculated as evoked release minus spontaneous release. Significant difference from control release (*P < 0.05, **P < 0.01, ***P < 0.001, Student’s t-test). Number of experiments is in parentheses.