Age-dependent sympathetic neural responses to ß1 selective beta-blockade in untreated hypertension-related tachycardia

AbstractBackground: Elevated heart rate (HR) increases cardiovascular morbidity and mortality in hypertension. The impact of beta-blockers on patient prognosis in hypertension is controversial. This study examined the age-related effects of betaxolol on HR, muscle sympathetic nerve activity (MSNA), blood pressure (BP) and sympathovagal balance in untreated males with hypertension and tachycardia.Methods: Ten young (age 26 ± 1 years) and seven older (age 50 ± 4 years) males underwent measurement of BP, HR, HR variability (Poincare plot) and MSNA before and after 8 weeks treatment with betaxolol at the initial starting dose of 10 mg/day, which was increased to 20 mg/day once daily after 4 weeks in all subjects.Results: In younger subjects, betaxolol decreased systolic BP (−13 ± 4 mm Hg, p = .01) and HR (−29 ± 4 bpm, p < .001) but not MSNA (3 ± 3 burst/min., p = 0.47) after 8 weeks. In older subjects a pronounced reduction in BP (−27 ± 7, p = .007) was accompanied by a significant decrease in MSNA (−13 ± 5 b...