We tested the hypothesis that blood pressure (BP) responses
to physical and mental stress are associated with polymorphisms
in the β-2 adrenergic receptor (AR) gene. We studied
normotensive, young, monozygotic (MZ) and dizygotic (DZ)
twins. The subjects underwent automated BP measurements
at the brachial and digital arteries and were subjected
to mental arithmetic and cold pressor stress. We used allele-specific
PCR to genotype four single nucleotide polymorphisms in
the β-2 AR gene. The most functionally relevant polymorphism
in the β-2 AR gene, Arg16/Gly, was associated with
systolic and diastolic BP under resting conditions, during
mental arithmetic, and during the cold pressor test, as
well as with the increase in diastolic BP during both forms
of stress. These findings support a role for the β-2
AR gene in BP regulation. They also indicate that the β-2
AR gene influences the level of not only resting but also
stress-related BP.