Studies on the neurotransmitter binding to pig brain microvessels.

Microvessels from pig brain areas were prepared by differential centrifugation techniques. These fractions were assayed for purity and structural unity by marker enzyme determination, light and electron microscopy. Binding properties of 3H-flunitrazepam were studied in different brain regions. Kinetic studies of 3H-flunitrazepam showed BMax-values of 0,42 +/- 0,3 pmol/mg protein and KD-values of 1,26 +/- 0,6 nM and were compared to a synaptosomal membrane fraction (P2-fraction) with BMax = 2,68 +/- 0,5 pmol/mg protein and a KD of 1,95 +/- 0,3 nM. GABA kinetic studies gave IC50-values of 250 nM in the microvessel fraction and 40 nM in the P2-fraction.