β-Adrenergic Receptors and Reflex Tachycardia After Single and Repeated Felodipine Administration in Essential Hypertension

To verify the possible contribution of β-adrenergic receptor down-regulation to the reversal of reflex tachycardia during chronic treatment with a dihydropyridine calcium antagonist, 11 hypertensive patients were studied with noninvasive blood pressure (BP) and heart rate (HR) monitoring after a placebo period, and on the first and seventh day of felodipine administration, 5 mg twice daily. Plasma catecholamines and neutrophil β-adrenergic receptors were measured on the first and seventh day of treatment, immediately before and 2 h after drug administration