Dietary sodium restriction sex specifically impairs endothelial function via mineralocorticoid receptor-dependent reduction in NO bioavailability in Balb/C mice.

Recent findings from our group demonstrated that females exhibit higher endothelial mineralocorticoid receptor (MR) expression than males, which predisposes them to aldosterone-mediated endothelial dysfunction in the context of metabolic disorders. However, whether the endothelium of female mice presents a higher propensity to MR-mediated dysfunction than that of males in the absence of comorbidities remains unknown. We therefore sought to investigate whether increasing aldosterone production endogenously with sodium restriction impairs endothelial function in otherwise healthy female mice. We fed male and female Balb/C mice a normal (0.4% NaCl; NSD) or sodium-restricted diet (0.05% NaCl; SRD) for 4 wk. Females exhibited higher baseline endothelial function (relaxation to acetylcholine) and lower vascular contractility (constriction to phenylephrine, serotonin, and KCl). However, SRD impaired endothelial-dependent relaxation and increased vascular contractility in female mice, effectively ablating the baseline sex difference. Female sex also increased baseline adrenal CYP11B2 expression; however, SRD significantly enhanced CYP11B2 expression in male and female mice and ablated the sex difference. Nitric oxide synthase (NOS) inhibition with Nω-nitro-l-arginine methyl ester hydrochloride eliminated both sex as well as diet-induced differences in endothelial dysfunction. In accordance, females demonstrated higher vascular endothelial NOS expression at baseline, which SRD significantly decreased. In addition, SRD diminished vascular NOX4 expression in female mice only. MR blockade with spironolactone-protected female mice from decreases in endothelial-dependent relaxation but not increases in vascular contractility. Utilizing sodium restriction as a method to increase plasma aldosterone levels in healthy female mice, we demonstrated that female mice are more susceptible to vascular damage via MR activation in the vascular endothelium only.NEW & NOTEWORTHY Female sex confers improved endothelial relaxation and vascular constriction responses in female Balb/C mice compared with males under baseline conditions. Sodium restriction impairs endothelial function, which is nitric oxide dependent, and increases vascular contractility in association with reduced vascular endothelial nitric oxide synthase and NOX4 expression in female mice ablating the baseline sex difference. Mineralocorticoid receptor antagonism ablates sodium restriction-induced endothelial dysfunction, but not increased vascular contractility, in female mice.

Purification of Recombinant Human PARP-3.

The purification of poly(ADP-ribose) polymerase-3 (PARP-3) from overexpressing cells (Sf9 insect cells, Escherichia coli) has been updated to a fast and reproducible two-chromatographic-step protocol. After cell lysis, PARP-3 protein from the crude extract is affinity purified on a 3-aminobenzamide Sepharose™ chromatographic step. The last contaminants and the 3-methoxybenzamide used to elute PARP-3 from the previous affinity column are removed on the high-performance strong cation exchanger MonoQ™ matrix. This step allows also the concentration of the protein. The columns connected to an A° KTA™ purifier system allow the purification of the protein in three days with a high-yield recovery. As described in the protocol, more than 3 mg of pure and active human PARP-3 can be obtained from 1.5 L of E. coli culture.

Lack of Suppression of Aldosterone Production Leads to Salt-Sensitive Hypertension in Female but Not Male Balb/C Mice.

Clinical studies indicate that salt-sensitive hypertension is more prevalent in women than in men. However, animal models of salt sensitivity have primarily focused on the mechanisms of salt sensitivity in male animals; therefore, elucidation of these mechanisms in female animal models is needed. We have previously shown that female Balb/C mice have higher aldosterone synthase expression and aldosterone production than males. We hypothesized that female Balb/C mice develop salt-sensitive increases in blood pressure. Seven-day feeding of a 4% NaCl high-salt (HS) diet increased blood pressure in female mice without altering blood pressure in males. Females on an HS diet displayed no apparent increases in sodium retention as assessed by 24-hour urine collection, sodium balance measure, and saline loading excretion analysis. Females on an HS diet exhibited lower renin-angiotensin system activity (plasma Ang II [angiotensin II], plasma renin activity, and ACE [angiotensin-converting enzyme] activity) compared with males but developed a salt-induced elevation in adrenal aldosterone synthase expression and retained higher aldosterone levels than males on HS. This resulted in a higher aldosterone/plasma renin activity ratio in females compared with males on HS feeding. Adrenal mRNA expression of angiotensinogen and leptin receptor was increased in female mice on an HS diet. HS impaired endothelium-dependent relaxation in female mice only. MR (mineralocorticoid receptor) inhibition (eplerenone) restored blood pressure and endothelial function in females on an HS diet. Collectively, these data indicate that Balb/C mice develop sex-discrepant salt-sensitive hypertension likely via aldosterone-MR-mediated mechanisms involving impaired endothelium-dependent relaxation in females only. This study presents the first model of spontaneous sex-specific salt sensitivity, which mimics the human pathology.