Metoprolol prevents sodium retention induced by lower body negative pressure in healthy men.
BACKGROUND
Lower body negative pressure (LBNP) has been shown to induce a progressive activation of neurohormonal systems, and a renal tubular and hemodynamic response that mimics the renal adaptation observed in congestive heart failure (CHF). As beta-blockers play an important role in the management of CHF patients, the effects of metoprolol on the renal response were examined in healthy subjects during sustained LBNP.


METHODS
Twenty healthy male subjects were randomized in this double blind, placebo versus metoprolol 200 mg once daily, study. After 10 days of treatment, each subject was exposed to 3 levels of LBNP (0, -10, and -20 mbar) for 1 hour, each level of LBNP being separated by 2 days. Neurohormonal profiles, systemic and renal hemodynamics, as well as renal sodium handling were measured before, during, and after LBNP.


RESULTS
Blood pressure and heart rate were significantly lower in the metoprolol group throughout the study (P < 0.01). GFR and RPF were similar in both groups at baseline, and no change in renal hemodynamic values was detected at any level of LBNP. However, a reduction in sodium excretion was observed in the placebo group at -20 mbar, whereas no change was detected in the metoprolol group. An increase in plasma renin activity was also observed at -20 mbar in the placebo group that was not observed with metoprolol.


CONCLUSIONS
The beta-blocker metoprolol prevents the sodium retention induced by lower body negative pressure in healthy subjects despite a lower blood pressure. The prevention of sodium retention may be due to a blunting of the neurohormonal response. These effects of metoprolol on the renal response to LBNP may in part explain the beneficial effects of this agent in heart failure patients.
Wuerzner
Grégoire
G
Service de Néphrologie, Centre Hospitalier, Universitaire Vaudois, Lausanne, Switzerland.
Chiolero
Arnaud
A
Maillard
Marc
M
Nussberger
Jürg
J
Burnier
Michel
M
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage*; D000328:Adult; D006333:Heart Failure / Q000188:drug therapy; D006801:Humans; D007684:Kidney Tubules / Q000187:drug effects* / Q000378:metabolism; D008150:Lower Body Negative Pressure; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage*; D012079:Renal Circulation / Q000187:drug effects; D012083:Renin / Q000097:blood; D012964:Sodium / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000187:drug effects
D000319:Adrenergic beta-Antagonists; D012964:Sodium; D012083:Renin; D008790:Metoprolol