Effect of endothelin and endothelin A receptors on regional cerebral blood flow after traumatic brain injury in rabbits.

Objective: To investigate the effect of endothelin and endothelin A receptors (ETAR) on regional cerebral blood flow after traumatic brain injury (TBI). Methods: The changes of endothelin 1 (ET 1) content with radioimmunoassay, mRNA expression and the location of ETAR with in situ hybridization, and the function and effect of antagonist BQ123 on regional cerebral blood flow (rCBF) through intracisternal application were dynamically observed on 130 adult rabbits after TBI. Results: ET 1 increased significantly in regional brain tissues, and the expression of ETAR mRNA increased apparently and predominantly distributed in the cerebromicrovascular endothelium after trauma. The rCBF declined significantly, but by using selective ETAR antagonist BQ123 to treat the rabbits, the decrease of rCBF could be apparently prevented. Conclusions: It demonstrates that ET 1 may primarily contribute to the rCBF decrease after TBI, while providing that the role of ET 1 is mediated through ETAR.