Does cholesterol depletion have adverse effects on blood rheology?
Blood viscosity (eta B) at shear rates 10 and 100s-1, plasma viscosity (eta P), hematocrit (Hct), and whole blood cholesterol (Chol) were measured in 50 patients with a history of myocardial infarction or unstable angina pectoris. Erythrocyte morphology was also studied by scanning electron microscopy to determine the proportion of nondiscocytic erythrocytes (NDE). There was a significant positive correlation between Chol and eta P (r = 0.41, P < 0.004) and a highly significant negative correlation (r = -0.69, P < 0.001) between Chol and Tk, a viscometric index of erythrocyte rigidity based on relative blood viscosity at high shear (eta B/eta P) corrected for Hct. This latter result indicates Chol reduction in this population may increase erythrocyte rigidity. Twenty-five patients with Chol values in the range 4.0-8.0 mmol/L were commenced on a standard lipid-lowering diet and after eight weeks half were also given pravastatin (40 mg daily). After thirty-two weeks Chol had fallen significantly more in the pravastatin group (28%) than in the diet only group (11%, P = 0.005). There was no change in eta P for either group but a significant increase in Tk for the pravastatin group only (P = 0.011). The change in total cholesterol (delta Chol) for each patient over thirty-two weeks was negatively correlated with both the change in the index of erythrocyte rigidity (delta Tk) (r = -0.40, P = 0.044) and the change in the proportion of nondiscocytic erythrocytes (delta NDE) (r = -0.47, P = 0.026). These data suggest that cholesterol reduction within the normolipemic range may be associated with unfavorable changes in blood rheology.
Fawcett
J P
JP
School of Pharmacy, University of Otago, Dunedin, New Zealand.
Menkes
D B
DB
D000789:Angina, Unstable / Q000097:blood* / Q000178:diet therapy / Q000188:drug therapy; D001809:Blood Viscosity; D002784:Cholesterol / Q000097:blood*; D004907:Erythrocyte Deformability; D004912:Erythrocytes / Q000648:ultrastructure; D005260:Female; D006400:Hematocrit; D018056:Hemorheology; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000178:diet therapy / Q000188:drug therapy; D017035:Pravastatin / Q000627:therapeutic use
D002784:Cholesterol; D017035:Pravastatin