Carré J B, Morand O, Homayoun P, Roux F, Bourre J M, Baumann N
Laboratoire de Neurochimie, INSERM Unité 134, Hôpital de la Salpêtrière, Paris, France.
J Neurochem. 1989 Apr;52(4):1294-9. doi: 10.1111/j.1471-4159.1989.tb01878.x.
Purified rat brain microvessels have been shown to hydrolyze radiolabeled sphingomyelin by means of two different enzyme systems. Enzymatic activity was detected at pH 7.4 and was strongly stimulated by magnesium or manganese and inhibited by calcium. Activity at pH 5.1 could also be found and was not dependent on any of these cations. At neutral pH and in the presence of magnesium, the rate of sphingomyelin hydrolysis did not exhibit a linear relationship with protein concentration. In contrast, increasing the protein concentration from 0.05 to 0.5 mg/ml resulted in a constant increase of sphingomyelin hydrolysis at pH 5.1. Kinetic parameters of both neutral and acid activities have been determined and were similar in magnitude to values reported previously for neural sphingomyelinases. This work demonstrates the occurrence of a neutral sphingomyelinase activity in purified rat brain microvessels, an observation raising the question of its role at the level of the blood-brain interface.
纯化的大鼠脑微血管已被证明可通过两种不同的酶系统水解放射性标记的鞘磷脂。在pH 7.4时检测到酶活性，镁或锰可强烈刺激该活性，而钙则抑制该活性。在pH 5.1时也能发现活性，且该活性不依赖于任何这些阳离子。在中性pH且存在镁的情况下，鞘磷脂水解速率与蛋白质浓度未呈现线性关系。相反，将蛋白质浓度从0.05 mg/ml增加到0.5 mg/ml会导致在pH 5.1时鞘磷脂水解持续增加。已确定中性和酸性活性的动力学参数，其大小与先前报道的神经鞘磷脂酶的值相似。这项工作证明了纯化的大鼠脑微血管中存在中性鞘磷脂酶活性，这一观察结果引发了其在血脑界面水平作用的问题。
