PGE2 enhances cytokine-elicited nitric oxide production in mouse cortical collecting duct cells

it has been documented that arginine vasopressin (AVP) and prostaglandin E-2(PGE(2)) regulate water reabsorption in renal tubular cells. The present study was attempted to delineate the downstream signaling of AVP and PGE(2) in a cortical collecting duct cell line (M-1 cell). Using RT-PCR, we detected mRNA for V2 and VACM-1 but not for Vla and AII/AVP receptors of AVP. Furthermore, neither AVP nor V2 receptor agonist and antagonist alter cellular CAMP. These together with unchanged cellular Ca2+ by AVP suggested that AVP pathway was not operating in M-1 cells. All four classical PGE(2) receptors with EP3 and EP4 as the most prominent were detected in M-1 cells. PGE(2), 11-deoxy-PGE(1) (EP2 and EP4 agonist), and 17-phenyl-trinor-PGE(2) (EPI agonist) increased cellular concentration of cAMP. There was no effect of PGE, or EPI agonist on cellular Ca2+. These findings provide evidence of the involvement of PGE, cascade in M-1 cells. M-1 cells were capable of synthesizing nitric oxide (NO). Although individual cytokines did not affect NO production, a mixture of tumor necrosis factor-alpha, interleukin- 1 beta, and interferon-gamma elevated NO concentration to 4.5-fold of the control. Addition of PGE, and db-cAMP to the cytokine mixture further increased NO production to 7.0-and 9.8-fold, respectively, of that seen in non-treated cells. PGE, or db-cAMP alone, however, had no effect on NO production. The results of the study led us to speculate that enhanced production of cAMP via PGE, signaling pathway in M-1 cells could either stimulate or attenuate water reabsorption in renal tubule. While an increase in cAMP alone may enhance water reabsorption, a concomitant increase in cAMP and cytokines may inhibit water reabsorption in renal tubule. (c) 2005 Elsevier Inc. All rights reserved.