Cardiac mRNA Expression in Inbred Rat Strains Divergent in Survival Time after Hemorrhage

Abstract

We previously identified inbred rat strains differing in survival time after severe controlled hemorrhage (StaH). To identify early biomarkers of hemorrhagic shock and genes that might explain differences in STaH, rats from three strains [Brown Norway (BN); Dark Agouti (DA), and Fawn Hooded Hypertensive (FHH)] with different StaH (DA = FHH > BN; 4-5 rats/group) were assigned to one of three treatment groups: non-operated controls (CNTL), surgically catheterized rats (CATH), or rats catheterized and bled (~46% hemorrhage) 24 h post-surgery (BLD). Rats were euthanized 30 min after handling or 30 min after start of a 26 min bleed. After euthanasia, hearts were removed and frozen in liquid nitrogen. Total RNA was isolated, fluorescently labeled, hybridized to Agilent rat whole genome microarrays, and statistically analyzed with BRB Array Tools. After controlling for multiple comparisons via the False Discovery Rate (<10%), mRNA expression for 65 known genes differed (P<.01). There were no inbred rat strain-related differences in mRNA expression (P>.05). Expression of 26 genes changed after BLD (20 decreased, 6 increased). These changes ranged from 5 to 556-fold. Genes with hemorrhage-associated changes included: Hif1α (22-fold decrease; oxygen homeostasis); Map4 (45-fold decrease; mitochondrial permeabilization); Mmp21 (24-fold decrease; Ca++ binding); Tubb5 (556-fold decrease; phagocytosis and protein complex binding); and Rnase10 (70-fold increase; nucleic acid binding). In the absence of inbred rat strain differences in mRNA expression, our data do not identify cardiac genes associated with differences in STaH. However, the data do provide new information concerning cardiac mRNA expression that rapidly changes after hemorrhage. Funding: US Army MRMC.