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EFFECT OF CROSS‐FOSTERING ON NEONATAL SODIUM BALANCE AND ADULT BLOOD PRESSURE IN THE SPONTANEOUSLY HYPERTENSIVE RAT
Author(s) -
Gouldsborough Ingrid,
Ashton Nick
Publication year - 1998
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1998.tb02178.x
Subject(s) - endocrinology , medicine , sodium , lactation , spontaneously hypertensive rat , potassium , blood pressure , calcium , chemistry , biology , pregnancy , organic chemistry , genetics
SUMMARY 1. The aim of the present study was to compare electrolyte handling in naturally reared neonatal spontaneously hypertensive rats (SHR) with those reared by a Wistar‐Kyoto (WKY) rat foster mother (denoted SHRX), as cross‐fostering SHR pups to a WKY rat dam lowers adult blood pressure in the SHR. 2. The electrolyte content of WKY rat and SHR dams’ milk was determined and electrolyte intake and urinary excretion rates were calculated in both naturally reared and cross‐fostered WKY rat and SHR pups. 3. The milk sodium concentration fell in both strains (WKY rat: 31.8 ± 2.0 to 15.2 ± 1.2 mmol/L; SHR 31.9 ± 2.5 to 18.2 ± 1.6 mmol/L; P < 0.001), as did potassium ( P < 0.001), over lactation, but there were no differences between strains. Calcium and magnesium concentrations increased ( P < 0.001), although SHR dam's milk contained less calcium ( P < 0.001) than that of WKY rat dams during the third week of lactation. 4. Spontaneously hypertensive rat pups ingested less milk ( P <0.05) than WKY rat pups; therefore, their cumulative sodium intake over postnatal days 4–15 was significantly lower than that of WKY rat pups (WKY rat vs SHR: 84.4 ± 3.6 vs 59.7 ± 2.6 μmol/g bodyweight, respectively; P < 0.05) and fostered SHRX pups (77.7 ± 7.0 μmol/g bodyweight; P < 0.05). Potassium and magnesium intakes were comparable between SHR, WKY rat and SHRX pups, but SHR pups ingested significantly less calcium than either WKY rat pups (136.1 ± 6.4 vs 200.1 ± 9.5p, mol/g bodyweight, respectively; P <0.05) or SHRX pups (200.0 ± 18.0 μmol/g bodyweight; P <0.05). 5. These data show that the neonatal SHR experiences a period of sodium deficiency during the developmental stage when cross‐fostering is effective in lowering blood pressure. This is consistent with the reported up‐regulation of the renin‐angiotensin system observed in SHR at this time and may have a long‐term influence on blood pressure.