Okada K, Ishikawa S, Saito T
Department of Medicine, Jichi Medical School, Tochigi, Japan.
Am J Physiol. 1991 Dec;261(6 Pt 2):F1007-12. doi: 10.1152/ajprenal.1991.261.6.F1007.
The present study was undertaken to examine the interrelationship between the arginine vasopressin (AVP)-induced dynamic changes in intracellular Ca2+ and Na+ concentrations in cultured rat aortic vascular smooth muscle cells (VSMC) by the direct measurements of intracellular Na+ concentration [( Na+]i), cytosolic free calcium [( Ca2+]i), and intracellular pH (pHi) using fluorescence dyes. AVP increased [Ca2+]i and [Na+]i in a dose-dependent manner; the rise in [Ca2+]i preceded the rise in [Na+]i. Pretreatment with the V1 antagonist [1-(beta-mercapto-beta, beta-cyclopentamethylenepropionic acid) 2-(O-methyl)-tyrosine] AVP [( d(CH2)5Tyr(Me)]AVP) completely blocked the effects of AVP on [Ca2+]i and [Na+]i. The V2 agonist 1-desamino-8-D-AVP, DDAVP, did not affect basal [Na+]i or the AVP-induced increase in [Na+]i. Also, Ca(2+)-free solution completely blocked the AVP-induced increase in [Na+]i. Moreover, Ca(2+)-free solution decreased the AVP-induced intracellular acidification and blunted the later AVP-induced intracellular alkalinization. These results therefore indicate that after binding to the V1 receptor AVP increases [Na+]i mediated by the activation of Na(+)-Ca2+ and Na(+)-H+ exchanges in VSMC. All of these cellular events are completely dependent on an increase in cellular Ca2+ uptake produced by AVP.
本研究旨在通过使用荧光染料直接测量细胞内钠离子浓度([Na⁺]i)、胞质游离钙浓度([Ca²⁺]i)和细胞内pH值(pHi)，来检测精氨酸加压素(AVP)诱导的培养大鼠主动脉血管平滑肌细胞(VSMC)内Ca²⁺和Na⁺浓度的动态变化之间的相互关系。AVP以剂量依赖的方式增加[Ca²⁺]i和[Na⁺]i；[Ca²⁺]i的升高先于[Na⁺]i的升高。用V1拮抗剂[1-(β-巯基-β,β-环戊亚甲基丙酸)2-(O-甲基)-酪氨酸]AVP[(d(CH₂)₅Tyr(Me)]AVP预处理可完全阻断AVP对[Ca²⁺]i和[Na⁺]i的作用。V2激动剂1-去氨基-8-D-精氨酸加压素(DDAVP)不影响基础[Na⁺]i或AVP诱导的[Na⁺]i升高。此外，无钙溶液完全阻断了AVP诱导的[Na⁺]i升高。而且，无钙溶液降低了AVP诱导的细胞内酸化，并减弱了随后AVP诱导的细胞内碱化。因此，这些结果表明，AVP与V1受体结合后，通过激活VSMC中的Na⁺-Ca²⁺和Na⁺-H⁺交换来增加[Na⁺]i。所有这些细胞事件都完全依赖于AVP引起的细胞Ca²⁺摄取增加。
