Blood-brain barrier permeability in senescent rats.

Cerebrovascular permeability to 14C-sucrose was measured in 3-mo-old and 28-mo-old conscious, restrained Fischer 344 male rats. Tracer was injected intravenously in these animals and arterial plasma concentrations were followed for 50 to 240 min, when animals were killed and regional brain radioactivity was measured. Equations derived by a two-compartment diffusion model were fit to concentration data to estimate PA (product of cerebral capillary permeability and surface area) and Ve (cerebral distribution space of 14C-sucrose). PA in 3-mo-old rats averaged 7.53 x 10(-6) sec-1 in 14 cerebral regions, and was not significantly elevated in 28-mo-old rats except possibly at white matter. Ve fell from an average of 0.126 in control rats to 0.070 in 28-mo-old rats. This 45% reduction may reflect a reduced extracellular space in the older animals. The findings do not support the hypothesis that aging of the central nervous system is related to breakdown of the blood-brain barrier.

在3月龄和28月龄清醒且受约束的Fischer 344雄性大鼠中测量了脑血管对14C - 蔗糖的通透性。在这些动物中静脉注射示踪剂，并在50至240分钟内监测动脉血浆浓度，之后处死动物并测量局部脑放射性。通过双室扩散模型推导出的方程与浓度数据拟合，以估算PA（脑毛细血管通透性和表面积的乘积）以及Ve（14C - 蔗糖的脑分布空间）。3月龄大鼠14个脑区的PA平均为7.53×10⁻⁶秒⁻¹，28月龄大鼠除可能在白质外，PA没有显著升高。Ve从对照大鼠的平均0.126降至28月龄大鼠的0.070。这种45%的降低可能反映了老年动物细胞外空间的减少。这些发现不支持中枢神经系统衰老与血脑屏障破坏有关的假说。