Atrial Natriuretic Peptide and Renal Haemodynamics in Newborn Calves

Abstract

Dratwa A.: Atrial Natriuretic Peptide and Renal Haemodynamics in Newborn Calves. Acta Vet. Brno 2006, 75: 477-483.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 7 th 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/m 2 (1 st day) and 338.25 ± 13.72 ml/min/m 2 (7 th day) and ERPF ranging between 179.77 ± 8.27 ml/min/m 2 (1 st day) and 245.22 ± 9.86 ml/min/m 2 (7 th day). The mean GFR on the first day was 35.68 ± 2.10 ml/min/m 2 and significantly (p ≤ 0.01) increased on the second day 49.97 ± 1.76 ml/min/m 2 , subsequently GFR remained on a stabile level average 51.06 ml/min/m 2 . 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.

Renal Regulation of Potassium Homeostasis in Calves in the First Week of Life Including the Role of Atrial Natriuretic Peptide

“…The author observed a high concentration of aldosterone on the first day of life, 30.62 pmol/l, a reduction on the second and third days to 18.87 and 19.12 pmol/l, respectively, an increase on the fifth day to 28.39 pmol/l, and a decrease again to 21.74 pmol/l observed on the seventh day. Table 1 Filtered load of potassum (F K ), potassium tubular reabsorption (TR K ), potassium excretion in the urine (U•V K ), potassium clearance (C K ), blood plasma potassium concentration (P K ) in calves in the first week of life and significant differences (SD) between values in the following days of life The increase in potassium excretion in the urine observed in this experiment during the first week of life, as well as the previously noted increase in blood plasma ANP concentration with age (DRATWA 2006), but also the highest amount of potassium clearance observed with the highest blood plasma ANP concentration (DRATWA 2006), may imply (despite the lack of statistical significance) that ANP plays a role in regulation of potassium excretion in the urine. The increase in excretion of potassium in the urine after administration of exogenous ANP to animals, observed in adult dogs (KIMURA et al 1986), adult rats (RAKOTONDRAZAFY et al 1996), and in sheep fetuses (SHINE et al 1987), may confirm the above assumptions.…”

“…In our previous studies, we demonstrated a statistically significant (P#0.01) increase in blood plasma ANP during the first seven days of calf life (DRATWA 2006). On the first day of life, the concentration of the hormone was 5.72 pmol/l, while on day 7, the concentration increased to 14.34 pmol/l.…”

“…Blood and urine samples were collected daily in accordance with a previously described procedure (DRATWA 2006). The concentration of potassium in blood plasma and urine was determined photometrically (Flapho-4 flame photometer).…”

“…Mean values and standard deviations were calculated, the significance of differences was estimated and correlation coefficients were determined. Statistical analysis was performed using the package Statistica 6.0 (DRATWA 2006).…”

Changes in the plasma levels of several bone markers in newborn calves during the first two days of life

“…Circulating NTx is excreted in urine [ 8 , 18 ], unlike TRAP5b and BAP, which are degraded mainly in the circulation [ 16 , 21 ]. The glomerular filtration rate of calves is lowest during the first day of life [ 6 ]. Therefore, we postulate that this prolonged elevation of plasma NTx was due to immature renal function in newborn calves.…”