THE IDENTIFICATION AND CHARACTERIZATION OF OLIGODENDROCYTE THROMBOXANE A(2) RECEPTORS

The presence of functional thromboxane A(2) receptors in neonatal rat oligodendrocytes and human oligodendroglioma cells was investigated us ing immunocytochemistry, ligand affinity chromatography, radioligand b inding analysis, immunoblot analysis, and calcium mobilization studies . Immunocytochemical studies revealed the presence of receptor protein on both oligodendrocytes and human oligodendroglioma cells, Ligand af finity chromatography allowed for the purification of a protein with a n electrophoretic mobility (55 kDa) indistinguishable from human plate let thromboxane A(2) receptors. This affinity purified protein was imm unoreactive against a polyclonal anti-thromboxane A(2) receptor antibo dy. Intact human oligodendroglioma cells specifically bound [H-3]SQ29, 548 with a K-D of 4 nM and were found to have approximately 3500 bindi ng sites per cell. Human oligodendroglioma cells also demonstrated cal cium mobilization in response to receptor activation with U46619. Thes e results demonstrate the presence of a functional thromboxane A(2) re ceptor in oligodendrocytes and are consistent with previous observatio ns indicating a high density of thromboxane A(2) receptors in myelinat ed brain and spinal cord fiber tracts.