Hemodynamic parameters during normal and hypertensive pregnancy in rats: evaluation of renal salt and water transporters.

Abstract

OBJECTIVE:

To determine whether alterations in extracellular volume expansion observed during normal and hypertensive pregnancy run in parallel to changes in the mRNA expression of renal transporters.

METHODS:

Wistar rats were divided into four groups: control (C, n = 5); pregnancy (P, n = 5); N(omega)-nitro-l-arginine methyl ester (L-NAME; 50 mg/kg/d)-treated control (H, n = 6); and pregnant rats (HP, n = 6). Hemodynamic studies were performed on day 14 of pregnancy, at which time we also analyzed of the sodium transporters (NHE3, Na/K/2Cl and Na/Cl), potassium channel (ROMK2) and water channel (AQP2).

RESULTS:

As expected, P rats presented high cardiac output (CO) and normal blood pressure (BP), whereas H rats presented lower CO and elevated BP. A significant (threefold) increase in total vascular resistance and a decrease in stroke volume were observed in the HP group. Hypertension resulting from nitric oxide (NO) synthesis inhibition blunted systemic hemodynamic adaptations during pregnancy. Compared with C rats, mRNA expression of ROMK2 in P rats was lower, whereas that of AQP2 was higher. Expression of AQP2 was significantly higher in H than in C or HP groups. Expression of BSC and NHE3 was lower in the HP than in the P group. The NO inhibition also provoked renal transporter alterations in HP.

CONCLUSIONS:

Our results suggest that tubule transporter variants may mediate the hemodynamic adaptations seen during pregnancy, although we cannot rule out the hypothesis that other factors are also mediating hemodynamic changes.

• Authors: Np Abreu, Joisse Caria Barboza Monerat Tardin, Mirian Aparecida Boim, Ruy R Campos, Cassia T Bergamaschi, Nestor Schor
• Journal: Hypertension in pregnancy (Hypertens Pregnancy) Vol. 27 Issue 1 Pg. 49-63 ( 2008) ISSN: 1064-1955 [Print] England
• PMID: 18293204 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Aquaporin 2
• Ion Channels
• KCNJ1 protein, human
• Potassium Channels, Inwardly Rectifying
• RNA, Messenger
• SLC9A3 protein, human
• Slc9a3 protein, rat
• Sodium Chloride Symporters
• Sodium-Hydrogen Exchanger 3
• Sodium-Hydrogen Exchangers
• Sodium-Potassium-Chloride Symporters

Topics

• Animals
• Aquaporin 2 (metabolism)
• Disease Models, Animal
• Female
• Gene Expression
• Hypertension, Pregnancy-Induced (physiopathology)
• Ion Channels (metabolism)
• Kidney (metabolism, physiopathology)
• Models, Animal
• Potassium Channels, Inwardly Rectifying (metabolism)
• Pregnancy (physiology)
• Pregnancy Complications, Cardiovascular (physiopathology)
• RNA, Messenger (biosynthesis)
• Rats
• Rats, Wistar
• Sodium Chloride Symporters (metabolism)
• Sodium-Hydrogen Exchanger 3
• Sodium-Hydrogen Exchangers (metabolism)
• Sodium-Potassium-Chloride Symporters (metabolism)