Fig. 7.
Mesenteric lymphatic fluid (MLF) induces a [Ca2+] response in a small intestinal epithelial cell line transfected with LPA5 and activates primary cultured mouse DRG. We examined the activation of LPA5 by Ensure-derived MLF in mucosal hBRIE380i cells and mouse primary-cultured DRG heterologously expressing LPA5 tagged with GFP (LPA5-GFP) by using Fura-2 AM (Molecular Probes) in a [Ca2+]-imaging assay. A–C: MLF activated LPA5 in hBRIE380i cells of more than one phenotype. D and E: nontransfected cultured DRG were responsive to MLF. (E2) MLF/TRPV1-responsive neurons (capsaicin) showed low sensitivity to peptone. F–H: LPA5 activation by Ensure-derived MLF was greatly enhanced over the endogenous response in LPA5-expressing DRG, further indicating that lymph-responsive somas of the DRG could be from more than one neuronal origin. Y-axis is 340/380 nm emission ratio, which is proportional to the relative changes in [Ca2+]i. [Lymph was at 1:10 dilution, protease-activated receptor 2-activating protein (PAR2-AP, SLIGRL-NH2) 100 μM, capsaicin 10 nM.]