从培养细胞和组织中分离出的血管平滑肌细胞膜囊泡中的钠钙交换系统是相似的。
The Na+-Ca2+ exchange system in vascular smooth muscle cell membrane vesicles isolated from cultured cells and from tissue is similar.
作者信息
Matlib M A, Kihara M, Farrell C, Dage R C
机构信息
Department of Pharmacology and Cell biophysics, University of Cincinnati College of Medicine, OH 45267-0575.
出版信息
Biochim Biophys Acta. 1988 Mar 22;939(1):173-7. doi: 10.1016/0005-2736(88)90060-0.
The existence of a Na+-Ca2+ exchange system was investigated in sarcolemmal vesicles isolated from cultured cells of dog mesenteric artery. When Na+-loaded membrane vesicles were suspended in a Na+-free KCl medium to create an outwardly directed Na+ concentration gradient across the membrane, a time-dependent uptake of Ca2+ was observed. This uptake of Ca2+ was drastically reduced when the vesicles were suspended in NaCl medium to eliminate the Na+ concentration gradient across the membrane. Monensin also decreased Ca2+ uptake in Na+-loaded vesicles. The apparent Km for Ca2+ was 2.97 microM and the apparent maximum velocity was 4.27 nmol/min per mg protein. The data indicate that a Na+-Ca2+ exchange system exists in sarcolemmal membranes isolated from cultured cells and that it is similar to the system in membranes isolated from the tissue.
在从犬肠系膜动脉培养细胞中分离出的肌膜囊泡中研究了Na⁺-Ca²⁺交换系统的存在情况。当将装载有Na⁺的膜囊泡悬浮于无Na⁺的KCl培养基中以在膜上形成外向的Na⁺浓度梯度时，观察到Ca²⁺的时间依赖性摄取。当将囊泡悬浮于NaCl培养基中以消除膜上的Na⁺浓度梯度时，这种Ca²⁺摄取大幅减少。莫能菌素也降低了装载有Na⁺的囊泡中的Ca²⁺摄取。Ca²⁺的表观Km为2.97微摩尔，表观最大速度为每毫克蛋白质4.27纳摩尔/分钟。数据表明，从培养细胞中分离出的肌膜中存在Na⁺-Ca²⁺交换系统，且它与从组织中分离出的膜中的系统相似。
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