Plasma atrial natriuretic peptide in healthy calves and calves with congenital heart disease.

BACKGROUND: The basic and clinical implications of evaluating plasma atrial natriuretic peptide (ANP) concentration in calves are unknown. OBJECTIVE: 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). ANIMALS: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS AND CLINICAL IMPORTANCE: Measurement of plasma ANP concentrations in calves can provide additional information useful for predicting hemodynamic abnormalities.