Endothelin-1 (ET-1) is an amino peptide produced by endothelial cells with a potent vasoconstrictor activity; this effect is regulated by a release of other endogenous vasal factors. Recent studies have demonstrated that endothelin is capable of releasing from different tissues, and particularly from perfused organs such as spleen and kidney, many vasal factors and prostanoids. The present study investigates whether perfusion with a solution of endothelin-1 in rat isolated kidney can induce the release of histamine, another vasal factor (until now not investigated in relation with endothelin-1) and whether treatment with propionyl carnitine, a compound with vasoprotecting activity, inhibits this release. This research demonstrates that histamine released by rat kidney perfused with endothelin is lowered if previously treated with propionyl carnitine. This effect of propionyl carnitine can be considered to be another important factor in a complex mechanism involved in its vasoprotective and cardiovascular action.