Changes in circulating atrial natriuretic peptide in relation to the cardiac status of Rhesus monkeys after total-body irradiation

Purpose: In order to determine the presence of cardiac damage associated wi th total-body irradiation (TBI), both echocardiographic parameters and circ ulating levels of atrial natriuretic peptide (ANP) were measured in three d ifferent age-cohorts of Rhesus monkeys (Macaca mulatta) previously treated with TBI without additional chemotherapy, at post irradiation intervals up to 30 years, at the former TNO/Radiobiological Institute at Rijswijk. Materials and methods: Standard echocardiographic techniques were used to m easure cardiac dimensions and left ventricular function in situ. Plasma-ANP concentration was measured by radioimmunoassay (RIA). After necropsy, tiss ue samples from the heart were taken for histological analysis. Results: Plasma-ANP levels of animals which received TBI were significantly (P = 0.0005) elevated when compared to age-matched controls (66.3 +/- 8.4 vs. 33.1 +/- 5.7 ng/l). Moreover, a positive correlation (P = 0.032) betwee n plasma-ANP values and time post treatment was found in the TBI group. TBI affected cardiac dimensions; however, no significant differences in cardia c functional parameters were observed between the different treatment group s. Necropsy reports demonstrated slight but consistent cardiovascular damag e in several animals treated with TBI, in terms of increased incidence of m ild epicardial and coronary arterial wall fibrosis, compared to age-matched controls. Conclusions: The concentration of plasma-ANP proved to be an important para meter for subclinical cardiac damage. In humans, serial determinations of p lasma ANP in individual patients might provide relevant information about t he cardiac status after TBI. (C) 1999 Elsevier Science Ireland Ltd. All rig hts reserved.