Oligomycin B is a macrolide antibiotic initially produced by several species of Streptomyces. Oligomycin B inhibits mitochondrial F1F0 ATP synthase, binding the F0 subunit, inhibiting ATP synthesis; it displays antibacterial efficacy against a variety of bacteria. In myocardial tissue, oligomycin B decreases ATP concentrations and contractile function under normoxic conditions, but instead decreases the ATP depletion rate during ischemic or hypoxic conditions. When administered in large doses, oligomycin B causes hypertension, bradycardia, increased arterial PO2, and metabolic acidosis. Oligomycin B inhibits mitochondrial function and is often used to mimic hypoxia-induced conditions.