Shimizu S, Shimizu K, Paul R J
Department of Molecular and Cellular Physiology, University of Cincinnati, College of Medicine, Ohio 45267-0576, USA.
J Vasc Res. 1997 Sep-Oct;34(5):399-407. doi: 10.1159/000159248.
Tissues are often cold stored for physiological studies and for clinical transplantation. We report that cold storage induces a relaxation to reoxygenation after hypoxia (H/R) in de-endothelialized porcine coronary arteries. In fresh denuded arteries stimulated with U46619, H/R did not elicit relaxation. However, after overnight cold storage (4 degrees C), H/R elicited a transient relaxation with peak relaxation of 56 +/- 8% (n = 8), which was reproducible after 2 days of cold storage. The H/R relaxation was inhibited by methylene blue (10 microM) and LY83583 (10 microM), O2-hemoglobin (1 microM), or N(G)-methyl-L-arginine (0.2 mM), but neither N(G)-nitro-L-arginine (0.2 mM) nor cyclo-oxygenase inhibition was effective. Importantly, the H/R relaxation was attenuated by KCl (40 mM) or tetrabutylammonium chloride (5 mM), a non-selective inhibitor of K+ channels. Interestingly, authentic nitric oxide (NO)- or S-nitroso-N-acetylpenicillamine (SNAP)-induced relaxations were enhanced by cold storage in U46619 (0.1 microM) contractures. When tissues were contracted with KCl (40 mM), the enhancement in NO- or SNAP-induced relaxation by cold storage was markedly smaller than with U46619. Neither catalase (1,200 U/ml) nor 3-amino-triazole (50 mM), an inhibitor of catalase, affected the H/R relaxation. The duration of H/R relaxation also increased with the period of incubation at 37 degrees C in the organ bath. This was blocked by inhibition of NO synthesis or guanylate cyclase. Moreover, inhibition of protein synthesis with actinomycin D (0.1 microM) and cycloheximide (10 microM), or dexamethasone (1 microM), an inhibitor of NO synthase induction, blocked this increase in the duration of the H/R relaxation. The results suggest that in smooth muscle induction of NO pathway relaxation, which is in part mediated by K+ channels and inducible NO synthase, may be of importance to the understanding of ischemia/reperfusion responses in cold-stored arteries.
组织常被冷藏用于生理学研究和临床移植。我们报告称，冷藏会诱导去内皮猪冠状动脉在缺氧后复氧（H/R）时出现舒张。在用U46619刺激的新鲜剥脱动脉中，H/R并未引发舒张。然而，经过过夜冷藏（4℃）后，H/R引发了短暂的舒张，最大舒张幅度为56±8%（n = 8），在冷藏2天后仍可重现。H/R诱导的舒张被亚甲蓝（10μM）、LY83583（10μM）、氧合血红蛋白（1μM）或N（G）-甲基-L-精氨酸（0.2 mM）抑制，但N（G）-硝基-L-精氨酸（0.2 mM）或环氧化酶抑制均无效。重要的是，H/R诱导的舒张被KCl（40 mM）或四丁基氯化铵（5 mM，一种K+通道非选择性抑制剂）减弱。有趣的是，在U46619（0.1μM）收缩状态下，冷藏增强了内源性一氧化氮（NO）或S-亚硝基-N-乙酰青霉胺（SNAP）诱导的舒张。当组织用KCl（40 mM）收缩时，冷藏对NO或SNAP诱导舒张的增强作用明显小于用U46619时。过氧化氢酶（1200 U/ml）或过氧化氢酶抑制剂3-氨基三唑（50 mM）均未影响H/R诱导的舒张。H/R诱导舒张的持续时间也随着在器官浴中37℃孵育时间的延长而增加。这被NO合成或鸟苷酸环化酶的抑制所阻断。此外，用放线菌素D（0.1μM）和环己酰亚胺（10μM）抑制蛋白质合成，或用NO合酶诱导抑制剂地塞米松（1μM），均阻断了H/R诱导舒张持续时间的这种增加。结果表明，在平滑肌中，由K+通道和诱导型NO合酶部分介导的NO途径舒张的诱导，可能对理解冷藏动脉中的缺血/再灌注反应具有重要意义。
