The changes in endothelium-derived vascular regulatory factors during dobutamine (DOB)-induced myocardial ischemia (MI) were investigated in 21 patients with Kawasaki disease aged from 11 months to 18 years. They were classified into an ischemia group (8 patients) and a non-ischemia group (13 patients) based on the results of 99mTc myocardial scintigraphy and DOB stress 99mTc myocardial scintigraphy. In the ischemia group, MI was relatively mild, because there were ischemic changes on the electrocardiogram and no significant symptoms during DOB stress. Catheters were positioned near the orifice of the coronary artery (Ao) and at the coronary sinus (CS). Hemodynamics and the blood concentrations of lactic acid and endothelin-1, as well as NO3-, 6-keto-prostaglandin F1alpha, and thromboxane B2, (which are inactive metabolites of nitric oxide, prostaglandin I2 and thromboxane A2, respectively), were measured at rest and after DOB stress (maximum dose: 30 microg x kg(-1) x min(-1)). The CS/Ao ratio was determined for all parameters. The rate-pressure product, an index of work load, and the cardiac index were significantly increased by DOB stress in both groups. Coronary angiography showed no vasospasm of the epicardial coronary arteries before or after DOB stress in either group. The plasma concentrations of endothelin-1 and 6-keto-prostaglandin F1alpha were significantly increased after DOB stress in the ischemia group, but the serum concentration of NO did not increase. The lack of an increase in NO production during DOB stress may have contributed to the worsening of MI in patients with Kawasaki disease.