Toursarkissian B, Endean E D, Aziz S M
Department of Surgery, College of Medicine, University of Kentucky Medical Center, Lexington 40536-0084.
J Surg Res. 1994 Sep;57(3):401-7. doi: 10.1006/jsre.1994.1161.
Increased arterial wall polyamine content has been linked to intimal hyperplasia (IH) formation. Intracellular polyamine content may be regulated by a polyamine transmembrane transport mechanism, but the existence of such a system has not been demonstrated in systemic arterial smooth muscle cells. This study characterizes polyamine transport as found in rat aortic smooth muscle cells. Smooth muscle cells were isolated and cultured from Sprague-Dawley rat aortas. Polyamine transport was determined by adding [14C]-polyamines to the medium, calculating transport kinetic parameters, Vmax and Km. Competition studies with unlabeled polyamines and uptake in the presence of paraquat, a polyamine transport inhibitor, were done to test the specificity of the uptake system. We identified polyamine transporters in aortic smooth muscle cells which were temperature, concentration, and time dependent. Kinetic studies revealed that spermidine and spermine had greater affinity for the transporter(s) than putrescine (Km = 0.3, 0.3, and 3.7 microM respectively; P = 0.0001) while maximum uptake velocity was similar for all polyamines (26.6-31.0 pmole/mg protein/min). Inhibition of de novo polyamine synthesis upregulated polyamine transport 2.8-3.8 times (P = 0.0001) while transporter affinity (as reflected by Km) remained unchanged. Competition studies and paraquat treatment indicated the presence of two polyamine transporters: one shared by all polyamines, the other specific for spermine and spermidine. These data indicate that transmembrane polyamine transport occurs in arterial smooth muscle cells. Upregulation of this system may represent one control mechanism for IH development.
动脉壁多胺含量增加与内膜增生（IH）的形成有关。细胞内多胺含量可能受多胺跨膜转运机制调控，但这种系统在全身动脉平滑肌细胞中尚未得到证实。本研究对大鼠主动脉平滑肌细胞中的多胺转运进行了表征。从Sprague-Dawley大鼠主动脉中分离并培养平滑肌细胞。通过向培养基中添加[14C] - 多胺、计算转运动力学参数Vmax和Km来测定多胺转运。进行了未标记多胺的竞争研究以及在多胺转运抑制剂百草枯存在下的摄取实验，以测试摄取系统的特异性。我们在主动脉平滑肌细胞中鉴定出了多胺转运体，其具有温度、浓度和时间依赖性。动力学研究表明，亚精胺和精胺对转运体的亲和力高于腐胺（Km分别为0.3、0.3和3.7 microM；P = 0.0001），而所有多胺的最大摄取速度相似（26.6 - 31.0 pmole/mg蛋白/分钟）。抑制多胺的从头合成可使多胺转运上调2.8 - 3.8倍（P = 0.0001），而转运体亲和力（由Km反映）保持不变。竞争研究和百草枯处理表明存在两种多胺转运体：一种为所有多胺所共有，另一种对精胺和亚精胺具有特异性。这些数据表明跨膜多胺转运发生在动脉平滑肌细胞中。该系统的上调可能代表内膜增生发展的一种控制机制。
