Quantitative genetic analysis of blood pressure response during the cold pressor test

Background: The genetic association between blood pressure (BP) at rest and during the cold pressor test (CPT) is not well characterized. The purpose of this study was to examine the genetic architecture of BP during the CPT, and to determine whether BP at rest and during the CPT share common genetic influences. Methods: In 419 individuals distributed across four large families, variance components methods were used to estimate heritabilities of resting BP and CPT BP, along with genetic correlations among BP traits. The CPT consisted of immersion of the left foot in 4°C water while the participant was supine. Blood pressure reactivity (ΔBP) was defined as BP at 15 to 30 sec and 45 to 60 sec of foot immersion minus resting BP. Results: Significant (P < .05) heritabilities were found for supine BP (h²_SBP = 0.35), CPT BP (h²_SBP = 0.27 and 0.33, h²_DBP = 0.18 and 0.30), and ΔSBP (h²_SBP = 0.12 and 0.37) but not for ΔDBP. Bivariate analyses detected significant (P < .05) genetic correlations between resting SBP and CPT SBP that were different from 0 and 1. Genetic correlations between resting DBP and CPT DBP were not significantly different from 1. Genetic correlations between resting SBP andΔSBP were not significant. Conclusions: Measures of BP at rest and during cold immersion are significantly influenced by additive genetic effects. These genetic influences are only partially shared between SBP at rest and SBP during cold immersion, suggesting that a somewhat different set of genes may influence SBP during cold immersion. Unique sets of genes also appear to influence ΔSBP independent of those influencing resting SBP.