We investigated the effects of sodium 2[5-(4-chlorophenyl)-pentyl]-oxirane-2-carboxylate (POCA) on regional myocardial function and metabolism in anesthetized, thoracotomized dogs subjected to a 53.5% reduction in flow through the circumflex branch of the left coronary artery (LCX). Regional function in the area supplied by the LCX and the left anterior descending coronary artery (LAD) was assessed by means of two pairs of subendocardially inserted ultrasonic transducers. Hemoglobin content, oxygen saturation, pH, PCO2, PO2, lactate, glucose, and free fatty acids were determined in arterial and local venous blood obtained from the area supplied by the LCX. POCA (20 mg/kg/20 min i.v.) induced a transient decrease in left ventricular power and cardiac output. Arterial free fatty acid (FFA) levels increased continuously throughout the experiment, whilst arterial glucose levels showed a continuous decrease. FFA uptake, lactate release, and oxygen uptake were reduced in the underperfused area by POCA. At the same time, POCA induced a transient increase in end-diastolic segment length and a sustained decrease in systolic shortening during the ejection phase in the underperfused area. No changes in regional function were observed in the area perfused by the nonconstricted LAD.