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Submitted on June 12, 2007
From the Aab Cardiovascular Research Institute and Department of Medicine, University of Rochester, NY. * To whom correspondence should be addressed. E-mail: Slava_Korshunov{at}URMC.rochester.edu.
Abstract—Axl, a receptor tyrosine kinase, was recently identified as a novel candidate gene in a genetic model of salt-sensitive hypertension (Sabra rat). Our group first reported that Axl plays a significant role in vascular remodeling in response to injury. Here we investigated the role of Axl in the pathogenesis of hypertension in a deoxycorticosterone acetate (DOCA)–salt model. Hypertension was induced in Axl wild-type (Axl+/+) mice and Axl-deficient (Axl-/-) mice by uninephrectomy and DOCA-salt for 6 weeks. Controls were uninephrectomized and received tap water and regular chow ad libitum. DOCA-salt treatment increased systolic blood pressure by 25 mm Hg in both genotypes after 1 week. Systolic blood pressure remained significantly elevated in Axl+/+ DOCA, whereas systolic blood pressure levels in Axl-/- DOCA mice were the same as controls at 6 weeks. DOCA-salt increased relative kidney weight and glomerular hypertrophy by 40% compared with controls in both genotypes. Consistent with levels of systolic blood pressure, endothelium-dependent vasorelaxation was impaired in Axl+/+ DOCA mice compared with Axl+/+ controls, whereas in Axl-/- DOCA mice relaxation responses were similar to Axl-/- controls. In addition, endothelium-independent vasorelaxation was improved in Axl-/- DOCA mice compared with Axl+/+ DOCA mice. Nitrotyrosine and phospho-Akt immunoreactivity was significantly reduced in arteries from Axl-/- DOCA mice compared with Axl+/+ DOCA mice. The remodeling index of the mesenteric artery (media:lumen ratio) was significantly increased in Axl+/+ DOCA mice compared with Axl-/- DOCA mice. Finally, increased vascular apoptosis in the Axl-/- DOCA mice suggests a likely mechanism for Axl-dependent effects on hypertension. These data strengthen the pathogenic role for Axl in salt-sensitive hypertension.
Revised on July 8, 2007
Axl Mediates Vascular Remodeling Induced by Deoxycorticosterone Acetate–Salt Hypertension
Vyacheslav A. Korshunov*;
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