Plasma Atrial Natriuretic Peptide in Healthy Calves and Calves with Congenital Heart Disease

The basic and clinical implications of evaluating plasma atrial natriuretic peptide (ANP) concentration in calves are unknown. To investigate the relationship between the plasma ANP concentration and left ventricular end-diastolic pressure (LVEDP) in healthy calves subjected to volume overload (Study 1), and to compare the plasma ANP concentration in calves with or without heart disease (Study 2). Six healthy calves were used in Study 1; disease calves and sick calves with (n = 9) and without congenital heart disease (CHD) (n = 9) were used in Study 2. In Study 1, LVEDP in anesthetized calves was manipulated by IV administration of acetated Ringer's solution (rate of 100 mL/kg/h for 20 minutes) and furosemide. In Study 2, disease calves were identified by blood examination and echocardiography or pathological examination. The plasma ANP concentration was determined by a chemiluminescence enzyme immunoassay for human alpha-ANP. In Study 1, preloading significantly increased the plasma ANP concentration (36 +/- 20-185 +/- 156, P < .01) and LVEDP (-11 +/- 7-2 +/- 12, P < .01) from the baseline. Furthermore, plasma ANP concentrations were strongly correlated with LVEDP (r = 0.61). In Study 2, the plasma ANP concentration was significantly higher in the calves with CHD than in the calves without heart disease (220 [67-970] versus 31 [10-86]; mean [range], P < .001). Measurement of plasma ANP concentrations in calves can provide additional information useful for predicting hemodynamic abnormalities.