Septic impairment of capillary blood flow requires activated coagulation pathway and is reversed by ascorbate through eNOS‐dependent dislodging of platelets in capillaries

Abstract

Sepsis impairs capillary blood flow, leading to organ failure. We hypothesized that activation of the coagulation pathway in sepsis contributes to this impairment and that ascorbate reverses impairment by blocking the pathway. Sepsis in mice was induced by feces injection into peritoneum (FIP). Impaired flow in the hindlimb skeletal muscle was assessed with intravital microscopy. At time 0, mice were injected i.v. bolus of saline, platelet‐depleting Ab, P‐selectin blocking Ab or antithrombin, and then assessed at 6 h post‐FIP. Alternatively, eptifibatide (GPIIb/IIIa inhibitor) or ascorbate was injected at 6 h and impairment assessed at 7 h post‐FIP. In some mice, we injected rhodamine 6 G to view platelet and leukocyte adhesion in capillaries at 7 h. Sepsis impaired flow (complete stoppage) in 40 % of capillaries. In wild type mice, platelet depletion, P‐selectin blocking, antithrombin, eptifibatide, and ascorbate all reduced impairment to ~20 %. Sepsis increased the number of adhering platelets ~8 fold (the number of adhering leukocytes was negligible). Blocking of P‐selectin, eptifibatide, and ascorbate reduced this increase down to 3.2 ‐ 4.7 fold. Reduction in impairment and adhesion by ascorbate was not seen in eNOS‐/‐ mice. Thus, impairment of flow requires platelets, is inhibited by anticoagulants, and reversed by ascorbate through eNOS‐dependent dislodging of platelets in capillaries. (Support: HSFO)