Role of albumin on endothelial basement membrane and hemostasis in a rat model of hemorrhagic shock

BACKGROUND We sought to determine the extent of loss of endothelial basement membrane (BM), leukocyte recruitment and changes in coagulation after hemorrhagic shock (HS), followed by limited-volume resuscitation (LVR) with 5% albumin (ALB). METHODS Anesthetized rats were bled 40% of blood volume and assigned to treatment groups: untreated (n = 6); LVR with normal saline (NS; n = 8); or LVR with ALB (n = 8). Sham rats (n = 6) underwent all procedures except hemorrhage or resuscitation. Blood samples were assayed for active proteases, such as metalloproteinase-9 (MMP-9) and a disintegrin metalloproteinase 10 (ADAM-10), BM-type heparan sulfate proteoglycan (perlecan), cell count and coagulation function. Leukocyte transmigration was used to estimate the net efficiency of leukocyte recruitment in cremaster venules. RESULTS Hemorrhage significantly lowered red cell count, but white cell and platelet counts did not change (vs. sham) Ionized calcium in plasma were significantly reduced in untreated and remained so after NS. In contrast, ionized calcium was normalized after albumin. Plasma expansion after NS and ALB further reduced leukocyte and platelet counts. MMP-9, ADAM-10 and perlecan were significantly higher in untreated rats (vs. sham). ALB normalized MMP-9, ADAM-10 and perlecan levels, while NS further increased MMP-9, ADAM-10 and perlecan (vs. sham). Transmigrated leukocytes doubled in the untreated group and remained elevated after NS (vs. sham) but normalized after ALB. ALB reduced every stage of the leukocyte recruitment process to sham levels. CONCLUSIONS Despite similar plasma expansion, NS weakened platelet function contrary to ALB. Plasma expansion with ALB resulted in restoration of BM integrity and attenuation of leukocyte recruitment to tissues, in contrast to NS. ALB plays a critical role in restoring BM integrity, attenuating leukocyte recruitment to tissues, and optimizing hemostasis by increasing ionized calcium in plasma.