The PI3K–Akt–eNOS pathway is involved in aortic hyporeactivity to Phenylephrine associated with late pregnancy in spontaneously hypertensive rats

Abstract

AimThis study aimed to evaluate the effects of Wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt), on aortic hyporeactivity to Phenylephrine (Phe) and nitric oxide bioavailability associated with pregnancy in hypertensive rats. Main methodsThe intact aortic rings of pregnant and non-pregnant Wistar or spontaneously hypertensive rats (SHRs) were stimulated with Phe (1nmol/L to 10mmol/L) before and after incubation with Wortmannin (10nmol/L, 30min). Western blot experiments analyzed the expression of phosphorylated PI3K [p85-PI3K], Akt [p-Akt (Ser 473)] and eNOS [p-eNOS (Ser 1177)] in aorta homogenates of pregnant and non-pregnant Wistar rats or SHRs. The effect of Wortmannin (10nmol/L) on the cytosolic concentrations of nitric oxide (NO; measured using 4,5-diaminofluorescein diacetate [DAF-2DA], 10mmol/L), Ca2+ (using Fluo 3-AM, 5μmol/L) and reactive oxygen species (ROS; using dihydroethidium [DHE], 2.5mmol/L) were measured fluorimetrically in freshly isolated endothelial cells. Key findingsWortmannin increases the reactivity of the aorta to Phe and decreases NO concentrations in the aortic endothelial cells of pregnant Wistar rats and SHR. SignificanceThe PI3/AKT/endothelial nitric oxide synthase (eNOS) pathway contributes to aortic hyporeactivity to Phenylephrine associated with pregnancy in normo- and hypertensive rats.