Hanif_2020_Mol.Cell.Biochem_465_37

Previously, we showed that adenosine A2A receptor induces relaxation independent of NO in soluble epoxide hydrolase-null mice (Nayeem et al. in Am J Physiol Regul Integr Comp Physiol 304:R23-R32, 2013). Currently, we hypothesize that Ephx2-gene deletion affects acetylcholine (Ach)-induced relaxation which is independent of A2AAR but dependent on NO and CYP-epoxygenases. Ephx2(-/-) aortas showed a lack of sEH (97.1%, P < 0.05) but an increase in microsomal epoxide hydrolase (mEH, 37%, P < 0.05) proteins compared to C57Bl/6 mice, and no change in CYP2C29 and CYP2J protein (P > 0.05). Ach-induced response was tested with nitro-L-arginine methyl ester (L-NAME) NO-inhibitor; 10(-4) M), N-(methylsulfonyl)-2-(2-propynyloxy)-benzenehexanamide (MS-PPOH) (CYP-epoxygenase inhibitor; 10(-5) M), 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE, an epoxyeicosatrienoic acid-antagonist; 10(-5) M), SCH-58261 (A2AAR-antagonist; 10(-6) M), and angiotensin-II (Ang-II, 10(-6) M). In Ephx2(-/-) mice, Ach-induced relaxation was not different from C57Bl/6 mice except at 10(-5) M (92.75 +/- 2.41 vs. 76.12 +/- 3.34, P < 0.05). However, Ach-induced relaxation was inhibited with L-NAME (Ephx2(-/-): 23.74 +/- 3.76% and C57Bl/6: 11.61 +/- 2.82%), MS-PPOH (Ephx2(-/-): 48.16 +/- 6.53% and C57Bl/6: 52.27 +/- 7.47%), and 14,15-EEZE (Ephx2(-/-): 44.29 +/- 8.33% and C57Bl/6: 39.27 +/- 7.47%) vs. non-treated (P < 0.05). But, it did not block with SCH-58261 (Ephx2(-/-): 68.75 +/- 11.41% and C57Bl/6: 66.26 +/- 9.43%, P > 0.05) vs. non-treated (P > 0.05). Interestingly, Ang-II attenuates less relaxation in Ehx2(-/-) vs. C57Bl/6 mice (58.80 +/- 7.81% vs. 45.92 +/- 7.76, P < 0.05). Our data suggest that Ach-induced relaxation in Ephx2(-/-) mice depends on NO and CYP-epoxygenases but not on A2A AR, and Ephx2-gene deletion attenuates less Ach-induced relaxation in Ang-II-infused mice.