Endothelin, cerebral ischaemia and infarction.

Endothelin-1 (ET-1) is a 21 aminoacid peptide with potent vasoconstrictor properties. It is synthesised and released by endothelial cells in both the peripheral and cerebral vasculature and is also localised within neurones in discrete brain areas where it may contribute to the central regulation of blood pressure. We have shown that intracisternal ET-1 in conscious rats induces a marked pressor response that is associated with an intense widespread reduction in cerebral blood flow. Subsequent studies with local application of ET-1 to the middle cerebral artery (MCA) revealed a dose dependent reversible vasoconstriction of the artery that resulted in profound reductions in local cerebral blood flow and the development of cerebral infarction. Thus abluminal application of ET-1 to the MCA offers a simple model of reversible focal cerebral ischaemia in the rat that complements the existing models of permanent MCA occlusion. The ET-1 model will help to provide new insights into the mechanisms of cerebral ischaemia and reperfusion injury, and to evaluate the usefulness of novel strategies of neuroprotection.