Pregnancy modulates the expression of NOX4 in aortas of SHR.

Abstract

The Phenylephrine (PE) hyporeactivity in different vessels of pregnant rats is modulated by the increased expression and activity of nitric oxide synthase (eNOS). However, the modulation of reactive oxygen species (ROS) on PE hyporeactivity in spontaneously hypertensive rats (SHR) aorta was not evaluated. We evaluated if ROS modulate the aortas reactivity to PE in pregnant (P) and non‐pregnant (NP) Wistar rats and SHR. Aortas were removed from NP and P rats to test the vascular reactivity, eNOS and NOX4 expression (Western Blot). Aortas reactivity to PE is reduced in P Wistar rats (Emax: P: 21.10 ± 1.8 mN, n=5; NP: 29.05 ± 1.4 mN, n=5) and SHR (Emax: P: 20.80 ± 2.2 mN, n=5; NP: 28.46 ± 1.7 mN, n=7). PE hyporeactivity is related to the increased expression of eNOS in aortas of P Wistar rats and SHR. NOX4 expression is similar in aortas of Wistar P and NP rats. The pre‐incubation of aortas with apocynin (100 µmol/L) decreased Emax of concentration‐effect curves to PE in aortas of P (12.17 ± 2.1 mN, n=5) and NP Wistar rats (19.05 ± 2.7 mN, n=5). These data indicate that ROS modulates the PE hyporeactivity in aortas of P Wistar rats. However, NOX4 is decreased in aortas of P compared to NP SHR. When we incubated the aortas of SHR with apocynin, Emax was not altered in aortas of P rats (16.95 ± 1.1 mN, n=5) and it was decreased in aortas of NP rats (19.03 ± 0.4 mN, n=6). Pregnancy reduces the expression of NOX4 in aorta of SHR. Our results suggest that ROS production is decreased in aorta of pregnant SHR and ROS do not participate of PE effect in aortas of pregnant SHR. Local Ethics Committee (CEEA‐FOA: Proc N 00658‐2013). Financial support: CAPES, CNPq and FAPESP (Grant: 2012/20398‐6).