Lack of difference in survival time to a severe controlled hemorrhage between rat strains bred for aerobic running capacity.

Hemorrhagic shock reflects low tissue perfusion that is inadequate to maintain normal metabolic functions. Often associated with this condition are impairments in cellular oxygen utilization. Rats bred for high (HCR) vs low (LCR) aerobic running capacity have greater O2 uptake and improved cardiovascular function (Gonzalez et al., J Appl Physiol 101: 1288, 2006). Hence, it was hypothesized that HCR would be more tolerant to global ischemia than LCR. To address this hypothesis, survival time to a severe controlled hemorrhage was measured. Male rats (generation 12) were catheterized and, ∼ 24 hours later, 55% of the calculated blood volume was removed during a 26 min period from conscious unrestrained animals. Rats were observed for 6 hr or until death. Contrary to our hypothesis, survival time in HCR (173 ± 55 min; n=8) did not differ (P = 0.24) from that in LCR (254 ± 52 min; n=8). Similarly, there were no differences between strains in blood pH, lactate, and base deficit values pre or post-hemorrhage. Since oxygen uptake and cardiac function are different in these rat strains, these results suggest that other mechanisms must play a more dominant role in determining survival time to hemorrhage. [ABSTRACT FROM AUTHOR]