The Gly16/Gly16 beta-2 AR genotype was associated with higher basal mean blood pressure (81.6 vs 75.2 mm Hg, P<0.01) and decreased salbutamol-induced vasodilation compared to the Arg16/Arg16 genotype.
Observational (n=57)
Observer-blinded
Do beta-2 adrenergic receptor variants affect resting blood pressure and agonist-induced vasodilation in young normotensive Caucasian men?
The Gly16 allele of the beta-2 adrenergic receptor is associated with higher resting blood pressure and blunted agonist-induced vasodilation, suggesting a potential mechanistic role in the pathogenesis of essential hypertension.
Absolute Event Rate: 81.6% vs 75.2%
p-value: p=<0.01
Recent evidence suggests that the prodownregulatory Gly16 allele of the beta-2 adrenergic receptor (beta-2 AR) is associated with essential hypertension in African Caribbeans. To further investigate the effect of the glycine (Gly)16 and arginine (Arg)16 beta-2 AR variants on hemodynamics, we investigated the agonist-mediated in vivo vasodilation in normotensive Austrian Caucasians and analyzed the results with respect to the Gly16/Arg16 polymorphism. Fifty-seven normotensive men, 20 to 32 years of age with body mass index of 18.7 to 29.9 kg/m2, were genotyped for the Arg16/Gly16 beta-2 AR alleles. All 15 Gly16/Gly16 subjects, all 12 Arg16/Arg/16 subjects, and 27 of 30 heterozygous subjects underwent hemodynamic measurements while supine after an overnight fast. The observers were unaware of the subjects' genotypes. The subjects received a graded infusion of the selective beta-2 AR agonist salbutamol (0.07, 0.14, and 0.21 microgram/kg per minute, respectively), each dose over 8 minutes. Stroke volume and blood pressure were determined continuously by means of impedance cardiography and oscillometry, respectively. The last 4 minutes of each infusion were evaluated statistically. Basal mean blood pressure was higher in the Gly16/Gly16 subjects compared with Arg16/Arg16 subjects (mean+/-SD: 81.6+/-6.14 versus 75.2+/-4.93 mm Hg, P<0.01). Homozygous Gly16 subjects showed a significantly decreased vasodilation during the first dose of salbutamol infusion compared with Arg16/Arg16 subjects (Deltatotal peripheral resistance index -17.9+/-14.4 versus -30. 6+/-8.3%, P<0.01) despite increased sympathetic counterregulation in the Arg16/Arg16 group (Deltaheart rate +16.9+/-7.0% versus +8.6+/-7. 0%, P<0.01; Deltacardiac index +39.5+/-18.5% versus 21.4+/-18.8%, P<0.05). Our results provide additional evidence that the Gly16/Arg16 alleles of the beta-2 AR are intimately related to blood pressure regulation and deserve further studies in the pathogenesis of essential hypertension.
Gratze et al. (Tue,) conducted a observational in Normotension (n=57). Gly16/Gly16 beta-2 AR genotype vs. Arg16/Arg16 beta-2 AR genotype was evaluated on Basal mean blood pressure (mm Hg) (p=<0.01). The Gly16/Gly16 beta-2 AR genotype was associated with higher basal mean blood pressure (81.6 vs 75.2 mm Hg, P<0.01) and decreased salbutamol-induced vasodilation compared to the Arg16/Arg16 genotype.