Hoffmann G, Ko Y, Sachinidis A, Göbel B O, Vetter H, Rosskopf D, Siffert W, Düsing R
Medizinische Universitäts-Poliklinik, Bonn, Germany.
Am J Physiol. 1995 Jan;268(1 Pt 1):C14-20. doi: 10.1152/ajpcell.1995.268.1.C14.
The kinetic properties of Na+/H+ exchange were investigated in vascular smooth muscle cells (VSMC) in culture from normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Antiport activity was measured in 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein-loaded cells after nigericin-induced cytosolic acidification. Studies were performed without (control) and with pretreatment of the cells with phorbol 12-myristate 13-acetate (PMA; 200 nM). Na+/H+ exchange markedly differed between the two strains with lower Hill coefficients [1.56 +/- 0.17 (SE) vs. 2.62 +/- 0.36] and higher maximal activity (Vmax) values (55.85 +/- 5.24 vs. 31.11 +/- 2.38 mmol H+.l-1.min-1) in SHR compared with WKY cell lines. PMA markedly altered the antiport kinetics in WKY VSMC with a decrease in the Hill coefficient (1.75 +/- 0.14) without affecting Vmax (31.88 +/- 1.55 mmol H+.l-1.min-1). In VSMC from SHR, PMA had no effect on the kinetic variables investigated. Thus two kinetic abnormalities are present with respect to Na+/H+ antiport activity in VSMC from SHR compared with WKY, i.e., increased Vmax and decreased Hill coefficient. The observation that PMA does not affect the kinetics of the Na+/H+ antiport in VSMC from SHR suggests a marked degree of antiporter prestimulation in this animal model of genetic hypertension.
研究了正常血压的Wistar-Kyoto（WKY）大鼠和自发性高血压大鼠（SHR）培养的血管平滑肌细胞（VSMC）中Na+/H+交换的动力学特性。在用尼日利亚菌素诱导胞质酸化后，测量了负载2',7'-双（羧乙基）-5（6）-羧基荧光素的细胞中的反向转运活性。研究在未预处理（对照）和用佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA；200 nM）预处理细胞的情况下进行。两种品系之间的Na+/H+交换存在显著差异，与WKY细胞系相比，SHR的希尔系数较低[1.56±0.17（SE）对2.62±0.36]，最大活性（Vmax）值较高（55.85±5.24对31.11±2.38 mmol H+.l-1.min-1）。PMA显著改变了WKY VSMC中的反向转运动力学，希尔系数降低（1.75±0.14），而不影响Vmax（31.88±1.55 mmol H+.l-1.min-1）。在SHR的VSMC中，PMA对所研究的动力学变量没有影响。因此，与WKY相比，SHR的VSMC中Na+/H+反向转运活性存在两种动力学异常，即Vmax增加和希尔系数降低。PMA不影响SHR的VSMC中Na+/H+反向转运动力学的观察结果表明，在这种遗传性高血压动物模型中，反向转运体存在明显程度的预刺激。
