All experiments adhered to the National Research.pdf

Functional, Metabolic, and Histological Changes of Vascular Tissues after Warm Ischemia 1 1 2 Shuji Moriyama, MD, Junichi Utoh, MD, Yoshinaka Murai, 1 1 2 Shoichiro Hagiwara, MD, Ryuji Kunitomo, MD, Katsuhide Nishi, MD, and Nobuo Kitamura, MD3 We examined functional, metabolic, and histological changes in the aortic tissue of rats after the period of warm ischemia ranging from 0 to 24 hours to determine the window of time in which grafts can be optimally viable for harvest. Sixty aortas from Brown Norway rats obtained after warm ischemia were used and changes in contraction, endothelial-de- pendent or -independent vasodilatation, cell viability, and histology were examined. Maxi- mal contraction induced by norepinephrine and potassium chloride decreased time-depen- dently after exposure to warm ischemia. The warm ischemic period when 50% of the maxi- mal contractile response of freshly isolated arteries was preserved, ranged from 6 to 8 hours. Maximal endothelium-dependent relaxation induced by acetylcholine decreased along with the time of warm ischemia. Endothelium-independent relaxation induced by sodium nitro- prusside and forskolin was unaltered for up to 9 hours. Cell viability gradually decreased, and a significant negative correlation was found between the warm ischemic period (T: hours) and cell viability ( V: %) (V = 101.9–2.35 T; r2 = 0.96; p 0.0001). Cell viability was greater than 70% within 12 hours postmorte