Figure 5.

Small GTP-binding proteins are not involved in the development of anti-CD3–induced water secretion or increased paracellular flux. (A) Net water movement was measured in wild-type mice injected with 200 μg of anti-CD3 and perfused with 10 μM Y27632, 100 μM NSC23766, or 20 μM AlF₄^– as indicated. Neither the Rho kinase inhibitor Y27632 nor the Rac1 inhibitor NSC23766 was able to prevent net water secretion after anti-CD3 treatment, and perfusion with the GTPase activator AlF₄^– did not induce net water secretion (n = 3). (B) Similarly, measurement of paracellular flux in the same treatment groups shown in A demonstrated that neither Y27632 nor NSC23766 was able to prevent anti-CD3–induced increases in paracellular flux, while AlF₄^– perfusion did not stimulate increased flux (n = 3).