Chronic hypoxia is a clinically important condition known to cause vascular abnormalities. To investigate the cellular mechanisms involved, we kept rings of a rat tail artery for 4 days in hypoxic culture (HC) or normoxic culture (NC) (PO₂ = 14 vs. 110 mmHg) and then measured contractility, oxygen consumption (JO₂), and lactate production (J_lac) in oxygenated medium. Compared with fresh rings, basal ATP turnover (J_ATP) was decreased in HC, but not in NC, with a shift from oxidative toward glycolytic metabolism. JO₂ during mitochondrial uncoupling was reduced by HC but not by NC. Glycogen stores were increased 40-fold by HC and fourfold by NC. Maximum tension in response to norepinephrine and the JO₂ versus tension relationship (JO₂ vs. high K⁺ elicited force) were unaffected by either HC or NC. Force transients in response to caffeine were increased in HC, whereas intracellular Ca²⁺ wave activity during adrenergic stimulation was decreased. Protein synthesis rate was reduced by HC. The results show that long-term hypoxia depresses basal energy turnover, impairs mitochondrial capacity, and alters Ca²⁺ homeostasis, but does not affect contractile energetics. These alterations may form a basis for vascular damage by chronic hypoxia.