Red blood cell volume (RBCV) and blood volume (BV) in male albino (NZW) rabbits with 99mTc.

Estimation of red blood cell volume (RBCV) and blood volume (BV) in experimental animals is important for studies concerning pharmaceutical distribution. In this study RBCV was measured, using 99mTc, in 64 male albino New Zealand rabbits with a body weight (BW) of 3.12 +/- 0.37 (SD) kg. The packed cell volume (PCV) was 38.17 +/- 2.37% (SD), the hematocrit (Hct) of the venous blood sample, corrected for trapped plasma, was PCV x 0.97 and the somatic hematocrit (Ho) was calculated as 0.89 x Hct. RBCV was measured using the pretinning method and the BV was calculated according to the formula BV = RBCV x 100/Ho. Labeling efficiency was 96.4% +/- 3.8% (SD). The RBCV was found to be 18.52 +/- 1.96 (SD) mL/kg (BW) and BV 56.12 +/- 4.82 (SD)mL/kg (BW). The correlation of the RBCV and BV to BW is given by the formulae: RBCV = 66.754 ln(BW(g)) - 478.702 (r2 = 0.624, P less than 0.001) and BV = -47.587 + 197.342 ln(BWkg) (r2 = 0.72, P less than 0.001). The 99mTc results do not differ significantly from those of the standard 51Cr procedure, but the 99mTc labeling method permits repetitive measurements at shorter intervals compared to 51Cr.