Little information is available about the direct action of angiographic contrast media on vasoactive peptides and allergy-mediated substances in humans. This study defined the acute effects of iopromide, a nonionic contrast medium (370 mg/mL iodine), on vasoactive peptides, allergy-mediated substances, and hemodynamic parameters in healthy volunteers. Pulmonary digital subtraction angiography was performed in seven healthy volunteers with no cardiovascular or pulmonary disease. Iopromide was administered as a total volume of 100 mL through a 7-Fr catheter inserted in the right femoral vein. The injected volumes and duration of injection (15-20 mL/second) were kept constant. The following hemodynamic parameters were monitored continuously: results of electrocardiogram, heart rate, and phasic and mean pulmonary arterial and peripheral arterial pressures. Blood samples were obtained before and 3 to 5 minutes after injection of contrast media to determine the concentrations of the following vasoactive peptides: renin, angiotensin I-converting enzyme, angiotensin II, aldosterone, atrial natriuretic peptide, antidiuretic hormone, cyclic guanosine monophosphate, and myoglobin; and to allergy-mediated substances such as tryptase, eosinophil protein X, and eosinophil cationic protein, using radioimmunoassay techniques. Iopromide substantially increased atrial natriuretic peptide (48.8 +/- 8.9 to 85.8 +/- 13.0) and antidiuretic hormone (3.4 +/- 0.3 to 4.6 +/- 0.5) levels, whereas renin decreased (0.9 +/- 0.1 to 0.8 +/- 0.2) slightly but not significantly. Iopromide did not induce substantial changes in the other vasoactive peptides or in allergy-mediated substances after the contrast medium was injected. Similarly, cardiovascular parameters (heart rate, pulmonary and systemic blood pressures, and results of electrocardiogram) also remained unchanged after contrast injection. Iopromide caused no appreciable hemodynamic alterations associated with the changes in atrial natriuretic peptide and antidiuretic hormone and no evidence of allergy-mediated reactions in all volunteers.