Genetic influences on blood pressure with the cold-pressor test: A twin study

Objectives To determine the genetic and environmental contributions to resting blood pressure, the level of blood pressure during the cold-presser test and the increase in blood pressure with the cold-presser test in an adult cohort of normotensive twins. Design and methods Ninety-one monozygotic and 41 dizygotic normal twin pairs were recruited by advertisement, The mean age was 34 +/- 14 years (mean +/- SD), Systolic blood pressure (SEP), diastolic blood pressure (DBP) and heart rate were measured continuously at the finger (using a Finapres device) and verified at the upper arm oscillometrically (using a Dinamap device) every minute. The cold-presser test was conducted by immersing the nondominant hand into cold (< 4 degrees C) water for 2 min, Statistical analysis was performed by using the SPSS program; parameters of the quantitative genetic models were estimated by path-analysis techniques using the LISREL 8 program. Results Heritability estimates of additive genetic effects were statistically significant for SEP and DBP but not for heart rate during rest and during the cold-presser test, Furthermore, the path analysis indicated shared as well as specific genetic components both for the blood pressure level at rest and for that during the cold-presser test, However, the genetic influences on the blood pressure level at rest and on the increase in blood pressure during the cold-presser test (the blood pressure level during the cold-presser test minus that during rest) were entirely independent of one another. Conclusions A significant genetic covariation exists for SEP and DBP during rest and during the cold-presser test, as well as a significant genetic variation that is specific to the cold-presser stress condition, These findings suggest that different genes or sets of genes contribute to blood pressure regulation during rest and to blood pressure reactivity to cold-presser stress.