Pregnancy prevents hypertensive remodeling and decreases myogenic reactivity in posterior cerebral arteries from Dahl salt-sensitive rats: a role in eclampsia?

Annet M. Aukes, Lisa Vitullo, Gerda G. Zeeman, Marilyn J. Cipolla*

*Corresponding author for this work

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    Abstract

    Previous studies have demonstrated that pregnancy prevents protective hypertension-induced remodeling of cerebral arteries using nitric oxide synthase (NOS) inhibition to raise mean arterial pressure (MAP). In the present study, we investigated whether this effect of pregnancy was specific to NOS inhibition by using the Dahl salt-sensitive (SS) rat as a model of hypertension. Nonpregnant (n = 16) and late-pregnant (n = 17) Dahl SS rats were fed either a high-salt diet (8% NaCl) to raise blood pressure or a low-salt diet (<0.7% NaCl). Third-order posterior cerebral arteries were isolated and pressurized in an arteriograph chamber to measure active responses to pressure and passive remodeling. Several vessels from each group were stained for protein gene product 9.5 to determine perivascular nerve density. Blood pressure was elevated in both groups on high salt. The elevated MAP was associated with significantly smaller active and passive diameters (P <0.05) and inward remodeling in the nonpregnant hypertensive group only. Whereas no structural changes were observed in the late-pregnant hypertensive animals, both latepregnant groups had diminished myogenic reactivity (P <0.05). Nerve density in both the late-pregnant groups was significantly greater when compared with the nonpregnant groups, suggesting that pregnancy has a trophic influence on perivascular innervation of the posterior cerebral artery. However, hypertension lowered the nerve density in both nonpregnant and late-pregnant animals. It therefore appears that pregnancy has an overall effect to prevent hypertension-induced remodeling regardless of the mode of hypertension. This effect may predispose the brain to autoregulatory breakthrough, hyperperfusion, and eclampsia when MAP is elevated.

    Original languageEnglish
    Pages (from-to)H1071-H1076
    Number of pages6
    JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
    Volume292
    Issue number2
    DOIs
    Publication statusPublished - Feb-2007

    Keywords

    • gestation
    • hypertension
    • brain
    • OXIDE SYNTHASE INHIBITION
    • BLOOD-BRAIN-BARRIER
    • OXIDATIVE STRESS
    • MIGRAINE
    • ENCEPHALOPATHY
    • PREECLAMPSIA
    • INNERVATION
    • PRESSURE
    • GENE
    • FLOW

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