Na + /H + Exchange in Vascular Smooth Muscle Cells Is Controlled by GTP-Binding Proteins

Author:

Orlov Sergei N.1,Aksentsev Sergei L.1,Pokudin Nickolai I.1,Tremblay Johanne1,Hamet Pavel1

Affiliation:

1. From the Research Center, Centre Hospitalier Universitaire de Montréal-(CHUM), Montreal, Quebec, Canada (S.N.O., J.T., P.H.), and the Laboratory of Biomembranes, Faculty of Biology, Moscow State University, Moscow, Russia (S.N.O., S.L.A., N.I.P.)

Abstract

This study examines the involvement of GTP-binding proteins (Gps) in the regulation of Na + /H + exchange and Ca 2+ influx, which are increased in vascular smooth muscle cells from spontaneously hypertensive rats. Gp activity was modulated by fluoride, GTPγS, GDPβS, and antisense oligodeoxynucleotides complementary to conserved regions of the α- and β-subunits of Gps (α-comm and β-comm, respectively). β-Adrenergic-induced G s -mediated cAMP production was used as a positive control to estimate the efficiency of these compounds. Na + /H + exchange, measured as ethylisopropyl amiloride-sensitive 22 Na influx, was activated by 5- to 6-fold by a 30-minute preincubation of cells with 10 mmol/L NaF with a K 0.5 for NaF of _13 mmol/L. In contrast, no activation of 45 Ca influx was observed under preincubation of vascular smooth muscle cells with NaF in Ca 2+ -free medium, whereas at [Ca 2+ ] o >0.5 mmol/L, simultaneous addition of 45 Ca and 10 mmol/L NaF led to sharply increased isotope uptake. NaF-induced 45 Ca influx did not reach saturation up to 3 mmol/L [Ca 2+ ] 0 and 20 mmol/L NaF and was correlated with the formation of calcium-fluoride complexes measured by light scattering. GTPγS increased basal cAMP production and Na + /H + exchange, whereas GDPβS decreased isoproterenol-induced cAMP production and Na + /H + exchange, α-comm reduced whereas β-comm augmented isoproterenol-induced cAMP production by 70%. Both oligodeoxynucleotides decreased basal Na + /H + exchange by 40% to 50%. NaF-induced Na + /H + exchange was not sensitive to α-comm but was inhibited by 60% in β-comm-loaded cells. Neither basal nor NaF-induced 45 Ca uptake was affected by GTPγS, GDPβS, and the oligodeoxynucleotides. Our results show that 45 Ca uptake is activated by NaF in vascular smooth muscle cells by nonspecific accumulation of calcium-fluoride complexes and is not related to modification of Gps. On the contrary, the Na + /H + exchanger is controlled by Gps, and Gp β-subunits are involved in [Ca 2+ ] 0 -independent activation of this carrier by NaF.

Publisher

Ovid Technologies (Wolters Kluwer Health)

Subject

Internal Medicine

Cited by 2 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3