Addition of adult serum improves endothelium-dependent relaxation of organ-cultured rat mesenteric artery via inhibiting mitochondrial reactive oxygen species.

Organ culture of blood vessels is a useful technique to investigate the long-term effects of drugs. Organ culture in a serum-free condition is so far the best way to maintain differentiated cell function. However some functional changes may occur from freshly isolated blood vessel (fresh) presumably due to lack of some key factors for vascular homeostasis in the medium. We investigated the long-term effects of addition of adult rat serum on acetylcholine-induced endothelium-dependent relaxation (EDR). Rat isolated mesenteric arteries were cultured for 3 days without (0% serum) or with 3% serum. In 0% serum, EDR was significantly impaired from fresh, whereas sodium nitroprusside-induced relaxation of smooth muscle didn't change. Addition of 3% serum significantly normalized the impaired EDR. Acute treatment with N-acetyl-l-cysteine or a mitochondrial inhibitor, rotenone normalized the impaired EDR in 0% serum. Mitochondrial superoxide production increased in the endothelium with 0% serum, which was normalized by 3% serum. Mitochondrial membrane potential increased in the endothelium with 0% serum, which was not normalized by 3% serum. In summary, the increased endothelial mitochondrial membrane potential in 0% serum may lead to mitochondrial reactive oxygen species (ROS) production and subsequent impairment of EDR. Addition of adult serum normalized the impaired EDR in part through inhibiting the increased mitochondrial ROS but not the membrane potential.