Atrial Natriuretic Peptide and Renal Haemodynamics in Newborn Calves

Abstract

The study was aimed to provide information on the dynamics of changes in the concentration of ANP in blood plasma of calves during the first seven days of their life and to find any association between blood plasma ANP concentration and effective renal blood (ERBF) and plasma flow (ERPF) and glomerular filtration rate (GFR). The experiment was carried out on 10 clinically healthy Black and White calves during the first seven days of postnatal life. The concentration of atrial natriuretic peptide (ANP) in blood plasma was determined with radioimmunoassay. The kidney function was assessed by clearance methods, using para-aminohippuric acid and inulin. The blood plasma ANP concentration increased with age. On the first day the mean concentration of ANP was 5.72 ± 1.34 pmol/l, on the 7th day it was 14.34 ± 2.09 pmol/l. The ERBF and ERPF during the first week of life showed variations, mean ERBF ranging within 280.22 ± 10.30 ml/min/m2 (1st day) and 338.25 ± 13.72 ml/min/m2 (7th day) and ERPF ranging between 179.77 ± 8.27 ml/min/m2 (1st day) and 245.22 ± 9.86 ml/min/m2 (7th day). The mean GFR on the first day was 35.68 ± 2.10 ml/min/m2 and significantly (p < 0.01) increased on the second day 49.97 ± 1.76 ml/min/m2, subsequently GFR remained on a stabile level average 51.06 ml/min/m2. The studies showed no correlations between plasma ANP concentration and ERPF (ERBF) and GFR. These data indicate that in calves during the first seven days of postnatal life endogenous ANP did not change the effective renal blood (plasma) flow and glomerular filtration rate.