Blood pressure and heart rate QTL in mice of the B6/D2 lineage: sex differences and environmental influences

1 Center for Developmental & Health Genetics, The Pennsylvania State University, University Park 2 Department of Biobehavioral Health, The Pennsylvania State University, University Park 3 Inter-Collegiate Program in Genetics, The Pennsylvania State University, University Park 4 Geisinger Medical Center, Weis Center for Research, Danville 5 Department of Comparative Medicine, Pennsylvania State College of Medicine, Hershey 6 Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 7 Department of Clinical Neurophysiology, Uppsala University, Uppsala, Sweden A quantitative trait locus (QTL) approach was used to define the genetic architecture underlying variation in systolic blood pressure (SBP) and heart rate (HR), measured indirectly on seven occasions by the tail cuff procedure. The tests were conducted in 395 F 2 adult mice (197 males, 198 females) derived from a cross of the C57BL/6J (B6) and DBA/2J (D2) strains and in 22 BXD recombinant-inbred (RI) strains. Interval mapping of F 2 data for the first 5 days of measurement nominated one statistically significant and one suggestive QTL for SBP on chromosomes (Chr) 4 and 14, respectively, and two statistically significant QTL for HR on Chr 1 (which was specific to female mice) and Chr 5. New suggestive QTL emerged for SBP on Chr 3 (female-specific) and 8 and for HR on Chr 11 for measurements recorded several weeks after mice had undergone stressful blood sampling procedures. The two statistically significant HR QTL were confirmed by analyses of BXD RI strain means. Male and female F 2 mice did not differ in SBP or HR but RI strain analyses showed pronounced strain-by-sex interactions and a negative genetic correlation between the two measures in both sexes. Evidence for a role for mitochondrial DNA was found for both HR and SBP. QTL for HR and SBP may differ in males and females and may be sensitive to different environmental contexts. quantitative trait locus; sex specificity; stress