This study examined the influence of the endothelium on metabolic and mechanical properties of porcine coronary arteries. Oxygen consumption rates (JO2) and lactate release (Jlac) under basal conditions were similar for intact (+E) and denuded (-E) rings. While passive tension was not different in2+E and -E arteries, the -E rings did develop a significant level of basal tone. With 50 mM KC1 stimulation, JO2and Jlacin both +E and -E arteries increased to similar levels, and developed force also was not different. While calculated total rates of ATP utilization (JATP) showed an increase in both +E and -E rings with 50 mM KCI stimulation, there were no differences attributable to the presence of the endothelium. In summary, the endothelium does not significantly alter the metabolic or mechanical properties of porcine coronary arteries, although it does appear to play a role in the suppression of basal tone.