Ability of Metoprolol to Alter the Exercise Induced Elevation of Catecholamines

Heart failure is a frequent disease in Denmark, and it is associated with very high mortality. Around 60,000 people in Denmark have heart failure, and there is about 11,000 hospitalizations every year due to this disease. From the time of diagnosis, patients survive an average of 4-5 years. A critical illness mechanism in heart failure is that these patients have high blood levels of catecholamines; epinephrine and norepinephrine, which is stress hormones from the sympathetic nervous system. Standard treatment of heart failure is with the two medical preparations betablockers and ACE-inhibitors. It is not known what effect betablocker-treatment have on blood concentration of epinephrine and norepinephrine. It is the purpose of this study, to investigate the effect of Selo-Zok ® (metoprolol) on the blood concentration of epinephrine and norepinephrine. This is done by creating a stress condition for the body, in this case with the bicycle test, while doing blood samples to determine the concentration of catecholamines. This will be done by 1-week treatment of tablet Selo-Zok ® followed by 1-week treatment of placebo (a substance with no medical effect). Blood samples will be taken to determine small changes in inheritance material (DNA) in the form of point mutations also called single nucleotide polymorphisms, since these changes can affect how we respond to metoprolol treatment.