Blood volumes in inbred rat strains with different survival times after severe hemorrhage

Abstract

We have previously shown 8‐fold differences in survival time among inbred rat strains after a 55% hemorrhage, and found a strong genetic component for this trait (Klemcke et al., Shock 29: 748, 2008). Blood volumes (BV) for all strains were assumed to be 5.83 % of body weight (BW), and BV removed was based on this figure. However, BV might vary in a strain‐dependent manner. If true, this may be one genetic variable affecting survival time after hemorrhage (STaH). To examine this possibility, we measured BV in select strains using an Evans blue procedure. BV varied among Brown Norway, Salt Sensitive, Fawn Hooded Hypertensive, Lewis, and DA rat strains respectively (9.16±.21a ; 7.45±.21b; 7.01±.24b,c ; 7.01±.22b,c ; 6.57±.22c % of BW; means with different letter superscripts are different, P<.01), and showed a heritability (h2) of 0.75. When these BV were used to calculate the % of BV removed from rats in our previous study, those percentages differed (37.0±0.3a; 45.4±0.5b; 50.0±0.4d; 47.8±0.9c; 52.1±.2e %; P<.01) and were highly and inversely correlated with previously determined STaH (r = ‐0.77; P <.01). These data indicate that previously noted differences in STaH among strains might be accounted for in part by removal of a different % of BV. They also suggest that BV −which is amenable to environmental (e.g., exercise) and genetic manipulation− is a genetically‐controlled characteristic that might be used to improve STaH.