The levels and the turnover of noradrenaline were measured in the left and right ventricles following left coronary artery ligation for 2 h in untreated, adrenalectomized or hexamethonium-treated rats. Noradrenaline in the left ventricles was decreased by ligation and unaffected in the right ventricles, whether of untreated, adrenalectomized or hexamethonium-treated animals. Turnover in the left ventricles, as estimated by the decrease of noradrenaline under dopamine beta-hydroxylase inhibition with bis-(4-methyl-1-homo-piperazinyl-thiocarbonyl)-disulfide (FLA-63), was unaffected by ligation whether in untreated, adrenalectomized, or hexamethonium-treated rats. Ligation accelerated turnover in the right ventricles of untreated rats or attenuated it in adrenalectomized rats and caused no changes in hexamethonium-treated rats. These results suggest that noradrenaline turnover in ischemic myocardium is not affected by regional ischemia and that such ischemia might accelerate turnover in the non-ischemic area, probably as a result of increased activity of sympatho-adrenal reflexes.