Effects of carbon monoxide (CO) delivery by a CO donor or hemoglobin on vascular hypoxia inducible factor 1α and mitochondrial respiration

We examined carbon monoxide (CO) delivery by carbon monoxide-releasing molecule 2 (CORM-2) or hemoglobin (Hb) on cellular oxygen sensing and mitochondrial respiration in bovine aortic endothelial cells (BAECs). CORM-2 reduced hypoxia-inducible factor-1α (HIF-1α) and endothelin-1 (ET-1) expression in normoxic and hypoxic cells, but while Hb alone significantly reduced HIF-1α stabilization in hypoxic cells, CO delivered by Hb (Hb-CO) had no effect on HIF-1α stabilization. CO dose-dependently increased basal oxygen consumption and reduced overall mitochondrial respiratory capacity. Hb-CO increased basal oxygen consumption but did not alter respiratory capacity. Together, CO reduced ET-1, and, at low doses, had no effect on endothelial mitochondria oxygen consumption. CO ligation to Hb may be developed further as non-vasoactive oxygen therapeutic without compromising mitochondrial function.

▸ CO delivered by CORM-2 reduces HIF-1α stabilization and expression of ET-1. ▸ CORM-2 dose-dependently disrupts mitochondrial function. ▸ CO ligated to Hb does not adversely affect mitochondrial function. ▸ CO ligated to Hb delivers less oxygen to target tissues than unligated Hb. ▸ This work provides new insight for CO therapeutics and effects on mitochondria.