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-p resser test and the increase in blood pressure with the cold-presser t est in an adult cohort of normotensive twins. Design and methods Ninet y-one monozygotic and 41 dizygotic normal twin pairs were recruited by advertisement, The mean age was 34 +/- 14 years (mean +/- SD), Systol ic blood pressure (SEP), diastolic blood pressure (DBP) and heart rate were measured continuously at the finger (using a Finapres device) an d verified at the upper arm oscillometrically (using a Dinamap device) every minute. The cold-presser test was conducted by immersing the no ndominant hand into cold (< 4 degrees C) water for 2 min, Statistical analysis was performed by using the SPSS program; parameters of the qu antitative genetic models were estimated by path-analysis techniques u sing 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, Furtherm ore, the path analysis indicated shared as well as specific genetic co mponents both for the blood pressure level at rest and for that during the cold-presser test, However, the genetic influences on the blood p ressure level at rest and on the increase in blood pressure during the cold-presser test (the blood pressure level during the cold-presser t est minus that during rest) were entirely independent of one another. Conclusions A significant genetic covariation exists for SEP and DBP d uring rest and during the cold-presser test, as well as a significant genetic variation that is specific to the cold-presser stress conditio n, These findings suggest that different genes or sets of genes contri bute to blood pressure regulation during rest and to blood pressure re activity to cold-presser stress.