Effect Of Plasma Cholesterol On Red Blood Cell Oxygen Transport

Abstract

SUMMARY1. Oxygen (O2) transfer from the blood to tissues is a function of the red blood cell (RBC) O2 saturation (SO2), the plasma O2 content being negligible. Under conditions of increased tissue O2 demand, the SO2 of arterial blood does not change appreciably (97%); however, the SO2 of mixed venous blood, equal to that of the perfused tissues, can go as low as 20%.2. Tissue O2 availability is limited by the exposure time to a RBC, which decreases under conditions of maximum stress (< 1 s). If the O2 unloading time was to increase significantly, because of a decrease in the RBC diffusion constant or an increase in the RBC membrane thickness, the RBC O2 unloading time would exceed tissue (e.g. cardiac) transit time and O2 transfer would be impaired.3. Cholesterol constitutes the non-polar, hydrophobic lipid of the enveloping layer of the RBC membrane. As the cholesterol content of the RBC increases, the fluidity of the membrane decreases and the lipid shell stiffens.4. Early studies demonstrated that high blood cholesterol concentrations were associated with reduced blood O2 transport; in essence, the haemoglobin dissociation curve was shifted to the left. 5. Current investigations have shown that the cholesterol RBC membrane barrier to O2 diffusion delayed O2 entry into the RBC during saturation and delayed O2 release from the RBC during desaturation. In an analysis of 93 patients divided by their cholesterol concentration into five groups, the percentage change in blood O2 diffusion was inversely proportional to the cholesterol concentration.6. The RBC membrane cholesterol is in equilibrium with the plasma cholesterol concentration. It stands to reason that as the plasma cholesterol increases, the RBC membrane becomes impaired and O2 transport is reduced.7. The implications of this new perspective on O2 transport include the ability to increase tissue oxygenation by lowering plasma cholesterol.

Docosahexaenoic acid: one molecule diverse functions

“…RBC deformability is also impaired by reduced membrane fluidity, which is reduced by decreased membrane fatty acid unsaturation [121] and increased by lipid peroxidation [122] and/or membrane cholesterol. Moreover, increased RBCmembrane cholesterol is accompanied with reduced oxygen unloading to the tissues [123]. Thus, DHAinduced improvements of these parameters in RBCs may improve the detrimental effects of Ab on RBCs and subsequently enhance the brain function in patients with AD.…”

Hypoxia: The Force that Drives Chronic Kidney Disease

“…This produces a greater barrier to oxygen diffusion that both delays oxygen entry into the erythrocyte during saturation and delays oxygen release during desaturation. [18][19][20] Indeed, the percentage change in blood oxygen diffusion has been found to be inversely proportional to plasma cholesterol concentration. 18 Consequently, cholesterol contributes to renal hypoxia by reducing the erythrocyte capacity to both load and release oxygen.…”

“…[18][19][20] Indeed, the percentage change in blood oxygen diffusion has been found to be inversely proportional to plasma cholesterol concentration. 18 Consequently, cholesterol contributes to renal hypoxia by reducing the erythrocyte capacity to both load and release oxygen. Hypercholesterolemia also results in lipid deposition in kidney tissue.…”

“…This in turn is driven by a constellation of interlinked risk factors. Primary amongst these factors are anemia, [6][7][8][9] diabetic hyperglycemia, [10][11][12] hypertension, [13][14][15][16][17] hypercholesterolemia, [18][19][20] cigarette smoking, [21][22][23][24][25][26][27] air pollution, [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] atherosclerosis, [43][44][45][46][47][48][49][50][51][52] repeated episodes of acute kidney injury, [53][54][55][56]…”

In Vitro Studies of Anti-Hemolytic and Cytotoxic Activity of Procyanidin-Rich Extract from the Leaves of Actinidia arguta

“…Oxidative damage occurs not only in membrane lipids but also in proteins, e.g. hemoglobin and spectrin, which in turn leads to irreversible structural changes and blood cell hemolysis [Becker et al, 1986;Buchwald et al, 2000]. The effect of oxidative stress on the physical properties and physiIn Vitro Studies of Anti-Hemolytic and Cytotoxic Activity of Procyanidin-Rich Extract from the Leaves of Actinidia arguta ological functions of RBCs depends on the nature of the oxidative agent [Borst et al, 2000;Hale et al, 2011].…”