Possible sources of endothelin-1 in damaged rat brain.

We investigated the sources of endothelin-1 (ET-1) detected in the damaged brain tissue of rats after cold injury. ET-1 in the injured sites was increased 1-5 days after the injury. Physiologic observations revealed that breakdown of the blood-brain barrier occurred and that plasma-derived albumin exuded into the brain parenchyma after cold injury. Radiolabeled ET-1, which was injected into the left cardiac ventricle, was detected in the tissue at the injury site, and ET-1-like immunoreactivity was observed in the brain capillaries in the damaged tissues. TGF-beta 1, which is a tissue regeneration factor, potently induced the expression of ET-1 mRNA in cultured astrocytes. These results suggest that ET-1 is produced through a variety of ways in the damaged brain.