Calponin phosphorylation in cerebral cortex microvessels mediates sustained vasoconstriction after brain trauma

OBJECTIVES: The purpose of this study was to determine the molecular and biochemical changes in the contractile protein, calponin (Cp), which temporally coincide with a previously reported state of sustained contractility following traumatic brain injury (TBI). METHODS: Double immunofluorescence, western analysis and two-dimensional non-equilibrium pH gradient gel electrophoresis (NEPHGE)/SDS-PAGE techniques were utilized to determine both the location and extent of Cp within smooth muscle cells (SM) and the phosphorylation state of Cp following TBI, as induced using a weight drop acceleration impact model. RESULTS: Double immunofluorescence for Cp and SM indicate that following injury, Cp migrates from the cytosol to a location subjacent to the SM membrane. Western analysis revealed a significant increase in Cp protein expression following injury that was maintained up to 48 hours post-injury. Combined Western analysis and NEPHGE indicated that Cp is phosphorylated following TBI. DISCUSSION: Cp migration and phosphorylation may underlie the mechanism for increased vasoreactivity leading to hypoperfusion following TBI.