PACAP receptor involved in the suppressive effect of PACAP on LC-induced TNFα stimulation in tubule cells. (A) Effect of PACAP38, VIP, and their specific antagonists on light chain–induced TNFα secretion in cultured human renal proximal tubule cells. M65 and PG97-269 are specific antagonists for PAC1 and VPAC1 receptors, respectively. For each antagonist 10–7 M was added with 10–9 M PACAP38 or VIP, respectively. Each column represents the mean of 3 replicates. Vertical bar shows SE of mean. *P < .05, **P < .01, and ***P < .001. (B) RT-PCR analyses of PAC1,VPAC1, and VPAV2 receptors in human bone marrow stromal cells (lane 1), human multiple myeloma cells (lane 2), and human renal proximal tubule cell line (lane 3). PAC1- and VPAC1-Rs were constitutively expressed in human bone marrow stromal cells, multiple myeloma cells, and proximal tubule cell line. Otherwise, VPAC2-Rs were expressed only in the stromal cells. Stimulation of the tubule cell line by the LC did not induce VPAC2-Rs.
