The effect of 60 min of in situ warm ischaemia (37 degrees C) on renal function was investigated in the rat model. In addition, the effect of pretreatment with intravenously administered furosemide, mannitol, propranolol, methylprednisolone, and adenosine triphosphate-magnesium chloride (ATP-MgCl2), singly or in combination, was studied. The ischaemic kidney was effectively protected by the administration of methylprednisolone alone but not by furosemide, mannitol, ATP-MgCl2, or propranolol singly or in combination. These results demonstrate that rat kidneys subjected to 60 min of warm ischaemia can be safely protected with methylprednisolone pretreatment (3 mg/100 g of body weight) 30 min before warm ischaemia.