Figure 3.

N3SP-1 prevents net mouse jejunal fluid secretion induced by CTx, Escherichia coli heat-stable enterotoxin, and anti-CD3 monoclonal antibody-induced inflammation. (A) Fluid accumulation (loop weight/length) 6 hours after inoculation of jejunal loops containing 1 μg purified CTx in presence of 400 nmol/L CP-1, N3SP-1, or PBS. P values are comparison with loops inoculated with only PBS by paired t tests. Results from at least 2 loops from 6 animals per condition. Representative loop distention shown below. (B) Intracellular localization of N3SP-1 in mouse jejunum 6 hours after loop inoculation with 1 μg CTx with 400 nmol/L CP-1 or N3SP-1 (upper) and localization of NHE3 under the same conditions (below). Scale bars = 20 μm. (C) Fluid accumulation (loop weight/length) 4 hours after inoculation of 3- to 4-cm jejunal loops with 0.5 μg purified E coli heat-stable (STa) enterotoxin in the presence of 400 nmol/L CP-1, N3SP-1, or saline. P values are comparison with loops inoculated with only saline by paired t tests. Results from at least 2 loops from 6 animals per condition. Representative loop distention is shown. (D) Fluid accumulation (loop wet weight/length) 2.5 hours after intraperitoneal injection of 200 μL saline or anti-CD3 antibody in mice with 2 jejunal loops containing 400 nmol/L CP-1 or N3SP-1. P values are comparison of loops inoculated with CP-1 compared with N3SP-1 and loops from intraperitoneal saline vs CD3 antibody by paired t tests. Results from 6 animals injected with saline and 6 with anti-CD3 antibody (total of 12 loops studied containing CP-1 or N3SP-1). (E) Studies performed as in panel A with CTx exposure but with 400 nmol/L CP-2 and N3SP-1Δ7 (n = 3). P values are comparison with PBS-inoculated loops by paired t tests. Data are shown as mean ± standard error of the mean.