Pinsky D, Oz M, Liao H, Morris S, Brett J, Sciacca R, Karakurum M, Van Lookeren Campagne M, Platt J, Nowygrod R
Department of Physiology, Columbia University, College of Physicians and Surgeons, New York 10032.
J Clin Invest. 1993 Dec;92(6):2994-3002. doi: 10.1172/JCI116922.
Current organ preservation strategies subject graft vasculature to severe hypoxia (PO2 approximately 20 Torr), potentially compromising vascular function and limiting successful transplantation. Previous work has shown that cAMP modulates endothelial cell (EC) antithrombogenicity, barrier function, and leukocyte/EC interactions, and that hypoxia suppresses EC cAMP levels. To explore the possible benefits of cAMP analogs/agonists in organ preservation, we used a rat heterotopic cardiac transplant model; dibutyryl cAMP added to preservation solutions was associated with a time- and dose-dependent increase in the duration of cold storage associated with successful graft function. Preservation was also enhanced by 8-bromo-cAMP, the Sp isomer of adenosine 3',5'monophosphorothioate, and types III (indolidan) and IV (rolipram) phosphodiesterase inhibitors. Neither butyrate alone nor 8-bromoadenosine were effective, and the cAMP-dependent protein kinase antagonist Rp isomer of adenosine 3',5'monophosphorothioate prevented preservation enhancement induced by 8-bromo-cAMP. Grafts stored with dibutyryl cAMP demonstrated a 5.5-fold increase in blood flow and a 3.2-fold decreased neutrophil infiltration after transplantation. To explore the role of cAMP in another cell type critical for vascular homeostasis, vascular smooth muscle cells were subjected to hypoxia, causing a time-dependent decline in cAMP levels. Although adenylate cyclase activity was unchanged, diminished oxygen tensions were associated with enhanced phosphodiesterase activity (59 and 30% increase in soluble types III and IV activity, respectively). These data suggest that hypoxia or graft ischemia disrupt vascular homeostasis, at least in part, by perturbing the cAMP second messenger pathway. Supplementation of this pathway provides a new approach for enhancing cardiac preservation, promoting myocardial function, and maintaining vascular homeostatic properties.
当前的器官保存策略会使移植器官的血管遭受严重缺氧（氧分压约为20托），这可能会损害血管功能并限制移植的成功率。先前的研究表明，环磷酸腺苷（cAMP）可调节内皮细胞（EC）的抗血栓形成性、屏障功能以及白细胞与内皮细胞的相互作用，并且缺氧会抑制内皮细胞中的cAMP水平。为了探究cAMP类似物/激动剂在器官保存中的潜在益处，我们使用了大鼠异位心脏移植模型；添加到保存液中的二丁酰环磷腺苷（dibutyryl cAMP）与成功移植功能相关的冷藏时间呈时间和剂量依赖性增加。8-溴环磷腺苷（8-bromo-cAMP）、腺苷3',5'-单磷酸硫代酸酯的Sp异构体以及III型（吲哚旦）和IV型（咯利普兰）磷酸二酯酶抑制剂也增强了保存效果。单独的丁酸盐或8-溴腺苷均无效，腺苷3',5'-单磷酸硫代酸酯的cAMP依赖性蛋白激酶拮抗剂Rp异构体可阻止8-溴环磷腺苷诱导的保存增强。用二丁酰环磷腺苷保存的移植物在移植后血流量增加了5.5倍，中性粒细胞浸润减少了3.2倍。为了探究cAMP在另一种对血管稳态至关重要的细胞类型中的作用，对血管平滑肌细胞进行缺氧处理，导致cAMP水平随时间下降。尽管腺苷酸环化酶活性未变，但氧张力降低与磷酸二酯酶活性增强有关（可溶性III型和IV型活性分别增加59%和30%）。这些数据表明，缺氧或移植器官缺血至少部分通过扰乱cAMP第二信使途径破坏血管稳态。补充该途径为增强心脏保存、促进心肌功能和维持血管稳态特性提供了一种新方法。
