SHIRAI, K., SAITO, Y., YOSHIDA, S. and MATSUOKA, N. Existence of Lipoprotein Lipase in Rat Brain Microvessels. Tohoku J. exp. Med., 1986, 149 (4), 449-450- To clarify the possibility that brain microvessels could utilize very low density lipoprotein (VLDL)-triglyceride, the hydrolysis of [¹⁴C] triolein in VLDL by rat brain microvessels was examined. The rat brain microvessels were prepared under microscopy. In the homogenate, triolein hydrolyzing activity was observed only in the presence of apolipoprotein C-II. That activity was diminished by the addition of 1M NaCl. [¹⁴C] triolein incorporated in VLDL was hydrolyzed time- dependently. These results suggested that there exists lipoprotein lipase in brain microvessels and the brain can utilize VLDL triglyceride as a source of fatty acids.