The characteristics of norepinephrine and epinephrine as well as plasma renin activity, angiotensin II, aldosterone, vasopressin, and atrial natriuretic factor (ANF) were examined in 64 patients (mean age of 52 +/- 16 years) with dilated cardiomyopathy. The findings were grouped according to the NYHA classification and compared with a normal cohort of 38 patients (mean age of 42 +/- 10 years). Furthermore, the influence of different cardioactive substances used in the treatment of cardiac failure was analyzed in more detail. Patients in NYHA class II already demonstrated an increased activity of the sympathicoadrenal, renin-angiotensin-aldosterone system (RAAS), vasopressin, and ANF system. The highest values were found in patients of NYHA class IV. In these patients, norepinephrine was enhanced by a factor of 7, epinephrine by a factor of 2, plasma renin activity by a factor of 7, angiotensin II by a factor of 2.5, aldosterone by a factor of 5, vasopressin by a factor of 1.5, and ANF by a factor of 4 compared with those in normal subjects. The highest correlation coefficient was found for norepinephrine (r = 0.84). The acute application of 1-2 mg/kg of body weight of enoximone in patients with dilated cardiomyopathy (n = 15) resulted only in a significant lowering of the atrial natriuretic factor as an indicator for drug-induced unloading effects (venous pooling). All the parameters showed only a tendency; in none could statistical significance be established. Application of 0.75 mg/kg of body weight of enoximone i.v. in patients with coronary artery disease (n = 17) has no direct influence either on the sympathoadrenal, the ANF, or the prostaglandin systems. It could be demonstrated that the mode of medical treatment influences the parameters of vasoconstrictor systems in different ways.