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INFLUENCE OF BETA‐BLOCKADE ON CIRCULATING PLASMA LEVELS OF 3‐METHOXY‐4‐HYDROXY PHENYLETHYLENE GLYCOL (MHPG) DURING EXERCISE IN MODERATE HYPERTENSION
Author(s) -
Drici Milou D.,
Roux Michel,
Candito Mirande,
Rimailho Alain,
Morand Philippe,
Lapalus P.
Publication year - 1991
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1991.tb01399.x
Subject(s) - medicine , endocrinology , norepinephrine , blockade , catecholamine , sympathetic nervous system , metabolite , epinephrine , placebo , chemistry , dopamine , blood pressure , receptor , alternative medicine , pathology
SUMMARY 1. The effect of exercise testing and β‐blockade on plasma norepinephrine (PNE), and secretion of its metabolite 3‐methoxy‐4‐hydroxyphenylethylene glycol (MHPG), was assessed in 28 mild‐to‐moderate hypertensives before and after the administration of dilevalol, a new β‐blocker with β 2 ‐agonism. 2. This double blind, placebo‐controlled study consisted of two successive submaximal exercise tests before and after the administration of a single oral dose of dilevalol (200 mg, 400 mg or 600 mg). Plasma norepinephrine levels were determined at rest, at 100 watts step of exercise and at maximal effort (E max ). 3. During the control test, mean PNE levels increased from 1.73±0.52 nmol/L (resting value) to 8.01 ± 4.01 nmol/L at E max ( P <0.01) as MHPG levels increased from 11.18 ± 1.33 nmol/L (rest) to 17.50 ± 1.15 nmol/ L (E max , P <0.01). After dilevalol, PNE increased significantly as compared to controls ( P <0.05), from 2.32 ± 0.99 to 12.42 ± 5.97 nmol/L ( P <0.01). PNE and MHPG levels were correlated, both at rest and during exercise. PNE levels after β‐blockade were linearly related to the dose of β‐blocker administered. MHPG levels were unaltered by the administration of dilevalol, both before and after exercise. 4. The increase in MHPG that occurs during bicycle exercise is largely generated from an increase in central nervous system noradrenergic activity. While dilevalol increases the peripheral sympathetic nervous system, both at rest and during exercise (which is reflected by increases in PNE levels) the drug does not alter resting central nervous system noradrenergic activity nor amplify the increase in central noradrenergic activity that occurs during exercise.