Roullet J B, Le Quan Sang K H, Luft U, Watanabe M, Otsuka K, McCarron D A, Devynck M A
Department of Nephrology, Hypertension and Clinical Pharmacology, Oregon Sciences Health University, Portland 97201, USA.
J Hypertens. 1997 Dec;15(12 Pt 2):1723-8. doi: 10.1097/00004872-199715120-00079.
Previous studies have shown that farnesol, a 15-carbon nonsterol derivative of mevalonic acid, inhibits vasoconstriction. Because of its lipophilic properties, we hypothesized that farnesol increased membrane dynamics, thus reducing uptake of Ca2+ and contraction.
To characterize the effect of farnesol on cell membrane fluidity.
The study was conducted using A7r5 cells, a rat aortic vascular smooth muscle cell line. Inhibition of Ca2+ uptake by farnesol was first established in these cells. Then, the effect of farnesol on membrane dynamics was determined. Finally, to ascertain that activation of Ca2+ extrusion and reuptake processes by farnesol did not occur, Ca2+-ATPase activity was examined.
Membrane fluidity in cell homogenates was estimated using two fluorescent dyes (1,6-diphenyl-1,3,5-hexatriene) and (1-[-(trimethylamino)-phenyl]-6-phenyl-1,3,5-hexatriene). Ca2+ uptake was determined by monitoring the changes in cytosolic Ca2+ concentration ([Ca2+]i) in fura-2-loaded cells after addition of KCI. Ca2+-ATPase activity was measured in 100000 x g cell fractions.
Farnesol reduced KCI-induced (Ca2+]i transients significantly (P < 0.001), but did not modify membrane dynamic properties [0.214+/-0.007 versus 0.218+/-0.007 (n = 10) and 0.142+/-0.002 versus 0.146+/-0.003 (n = 5) for 1 -[-(trimethylamino)-phenyl]-6-phenyl-1,3,5-hexatriene and 1,6-diphenyl-1,3,5-hexatriene anisotropies, respectively; NS]. Administration of up to 30 micromol/l farnesol did not affect Ca2+-ATPase activity.
Farnesol inhibits KCI-dependent rise of [Ca2+]i in A7r5 cells. This effect of farnesol is not related to a global change in plasma membrane lipid organization or to activation of Ca2+ pumps. Other mechanisms such as direct inhibition of voltage-dependent Ca2+ channels could therefore explain the biologic action of farnesol in the vascular tissue.
先前的研究表明，法尼醇是一种15碳的甲羟戊酸非甾醇衍生物，可抑制血管收缩。由于其亲脂性，我们推测法尼醇可增加膜动力学，从而减少Ca2+摄取和收缩。
表征法尼醇对细胞膜流动性的影响。
本研究使用大鼠主动脉血管平滑肌细胞系A7r5细胞进行。首先在这些细胞中确定法尼醇对Ca2+摄取的抑制作用。然后，测定法尼醇对膜动力学的影响。最后，为确定法尼醇不会激活Ca2+的外排和再摄取过程，检测了Ca2+-ATP酶活性。
使用两种荧光染料（1,6-二苯基-1,3,5-己三烯）和（1-[-(三甲基氨基)-苯基]-6-苯基-1,3,5-己三烯）评估细胞匀浆中的膜流动性。通过监测加入KCl后fura-2负载细胞中胞质Ca2+浓度（[Ca2+]i）的变化来测定Ca2+摄取。在100000×g细胞级分中测量Ca2+-ATP酶活性。
法尼醇显著降低了KCl诱导的（Ca2+]i瞬变（P < 0.001），但未改变膜动态特性[1-[-(三甲基氨基)-苯基]-6-苯基-1,3,5-己三烯和1,6-二苯基-1,3,5-己三烯各向异性分别为0.214±0.007对0.218±0.007（n = 10）和0.142±0.002对0.146±0.003（n = 5）；无显著性差异]。给予高达30 μmol/l的法尼醇不影响Ca2+-ATP酶活性。
法尼醇抑制A7r5细胞中KCl依赖性的[Ca2+]i升高。法尼醇的这种作用与质膜脂质组织的整体变化或Ca2+泵的激活无关。因此，其他机制如直接抑制电压依赖性Ca2+通道可能解释法尼醇在血管组织中的生物学作用。
