Critical Illness Research, Victoria Research Laboratories, Lawson Health Research Institute, London, ON, N6C 2V5, Canada.
Intensive Care Med. 2010 Nov;36(11):1928-34. doi: 10.1007/s00134-010-1969-3. Epub 2010 Aug 6.
Impaired microvascular perfusion in sepsis is not treated effectively because its mechanism is unknown. Since inflammatory and coagulation pathways cross-activate, we tested if stoppage of blood flow in septic capillaries is due to oxidant-dependent adhesion of platelets in these microvessels.
Sepsis was induced in wild type, eNOS(-/-), iNOS(-/-), and gp91phox(-/-) mice (n = 14-199) by injection of feces into the peritoneum. Platelet adhesion, fibrin deposition, and blood flow stoppage in capillaries of hindlimb skeletal muscle were assessed by intravital microscopy. Prophylactic treatments at the onset of sepsis were intravenous injection of platelet-depleting antibody, P-selectin blocking antibody, ascorbate, or antithrombin. Therapeutic treatments (delayed until 6 h) were injection of ascorbate or the glycoprotein IIb/IIIa inhibitor eptifibatide, or local superfusion of the muscle with NOS cofactor tetrahydrobiopterin or NO donor S-nitroso-N-acetylpenicillamine (SNAP).
Sepsis at 6-7 h markedly increased the number of stopped-flow capillaries and the occurrence of platelet adhesion and fibrin deposition in these capillaries. Platelet depletion, iNOS and gp91phox deficiencies, P-selectin blockade, antithrombin, or prophylactic ascorbate prevented, whereas delayed ascorbate, eptifibatide, tetrahydrobiopterin, or SNAP reversed, septic platelet adhesion and/or flow stoppage. The reversals by ascorbate and tetrahydrobiopterin were absent in eNOS(-/-) mice. Platelet adhesion predicted 90% of capillary flow stoppage.
Impaired perfusion and/or platelet adhesion in septic capillaries requires NADPH oxidase, iNOS, P-selectin, and activated coagulation, and is inhibited by intravenous administration of ascorbate and by local superfusion of tetrahydrobiopterin and NO. Reversal of flow stoppage by ascorbate and tetrahydrobiopterin may depend on local eNOS-derived NO which dislodges platelets from the capillary wall.
脓毒症中微血管灌注受损的治疗效果不佳，其原因尚不清楚。由于炎症和凝血途径相互激活，我们检测了在这些微血管中，由于氧化应激导致血小板黏附于毛细血管而引起血流停止的可能性。
通过向腹膜内注射粪便，在野生型、eNOS(-/-)、iNOS(-/-)和 gp91phox(-/-)小鼠（n = 14-199）中诱导脓毒症。通过活体显微镜评估后肢骨骼肌毛细血管中的血小板黏附、纤维蛋白沉积和血流停止情况。在脓毒症开始时进行预防性治疗，包括静脉注射血小板耗竭抗体、P-选择素阻断抗体、抗坏血酸或抗凝血酶。在 6 小时后进行治疗性治疗，包括注射抗坏血酸或糖蛋白 IIb/IIIa 抑制剂依替巴肽，或用一氧化氮合酶辅助因子四氢生物蝶呤或一氧化氮供体 S-亚硝基-N-乙酰青霉胺（SNAP）对肌肉进行局部灌流。
脓毒症 6-7 小时后，明显增加了停流毛细血管的数量和这些毛细血管中血小板黏附及纤维蛋白沉积的发生。血小板耗竭、iNOS 和 gp91phox 缺乏、P-选择素阻断、抗凝血酶或预防性抗坏血酸可预防，而延迟给予抗坏血酸、依替巴肽、四氢生物蝶呤或 SNAP 则可逆转脓毒症时的血小板黏附和/或血流停止。在 eNOS(-/-)小鼠中，抗坏血酸和四氢生物蝶呤的逆转作用缺失。血小板黏附可预测 90%的毛细血管血流停止。
脓毒症毛细血管灌注受损和/或血小板黏附需要 NADPH 氧化酶、iNOS、P-选择素和激活的凝血系统，并可通过静脉内给予抗坏血酸和局部灌流四氢生物蝶呤和 NO 来抑制。抗坏血酸和四氢生物蝶呤逆转血流停止可能依赖于局部 eNOS 衍生的 NO，其可将血小板从毛细血管壁上洗脱下来。
