1. A gene-drug interaction has been indicated between β₁-adrenoceptor-selective beta-blockers and the Arg389Gly polymorphism (rs1801253) in the adrenergic beta-1 receptor gene (ADRB1). In the present study, we investigated the effect of the ADRB1 Arg389Gly polymorphism on plasma renin activity (PRA) and heart rate (HR), as well as genotype-dependent responses to metoprolol and exercise. 2. Twenty-nine healthy male subjects participated in two treatment periods (placebo and 200 mg/day metoprolol). A 15 min submaximal exercise test was performed after each treatment period and PRA and HR were measured before and after exercise. 3. Before exercise, median PRA was lower in Gly/Gly subjects than in Arg/Arg subjects after both placebo (P = 0.030) and metoprolol (P = 0.020) treatment. After placebo, the exercise-induced increase in PRA was greater in Gly/Gly than Arg/Gly and Arg/Arg subjects (P = 0.033). The linear association between log(PRA) and log(metoprolol concentration) varied significantly between genotypes (P = 0.024). In Gly/Gly subjects, PRA decreased significantly with metoprolol concentration before (P = 0.025) and after exercise (P < 0.001), whereas in Arg/Gly and Arg/Arg subjects metoprolol concentration had no effect on PRA. The effect of metoprolol concentration on PRA in Gly/Gly subjects was enhanced by exercise (P = 0.044). No significant differences in HR were seen between genotype groups. 4. Resting PRA was lower in Gly/Gly than Arg/Arg subjects and the effect of exercise and metoprolol concentration on PRA was stronger in Gly/Gly subjects than with the other two genotypes. Thus, Gly/Gly heart failure patients may require lower doses of metoprolol than other patients to block neurohumoral hyperactivity.
Trial registration: ClinicalTrials.gov NCT00885651.
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