[Myocardial catecholamine content in heart failure--II: Measurement in endomyocardial biopsies, reference systems,...

To enable the assessment of a possible gradual loss of myocardial catecholamines in heart failure, we determined control values in endomyocardial biopsies from normal human right ventricular myocardium. The reproducibility of the determinations and its dependence on the reference system, wet weight (wwt) or non-collagen-protein (NCP), was investigated in explanted hearts. Parallel determinations of norepinephrine in several samples from 1-2 mg in the same heart yielded a variability of about 20%. To obtain reproducible values, catecholamine concentrations had to be related to non-collagen-protein. Non-collagen-protein content was higher in the ventricles (138 +/- 16 micrograms/mg wwt) than in the atria (102 +/- 15 micrograms/mg wwt). Norepinephrine levels in normal human myocardium, measured in right ventricular endomyocardial biopsies were 10.3 +/- 3 pg/micrograms NCP. If they were compared with norepinephrine levels in right atrial samples from 11 patients without heart failure, obtained at open heart surgery (17.6 +/- 6 pg/micrograms NCP), an atrioventricular gradient, with ventricular norepinephrine content being 58% of right atrial levels was calculated for healthy human hearts. This gradient was almost identical with that found in heart failure, patients, where right ventricular norepinephrine amounted to 60% of right atrial levels. This implicates a percentually homogeneous loss of norepinephrine in heart failure, which, however, does not equalize ventricular and atrial levels. Thus, to interpret myocardial catecholamine content in cardiac diseases, normal values in corresponding areas are mandatory.