The structure of the kidney in relation to age and diet in white rats during the weaning period

Boss, Jeffrey; Dlouhá, H; Kraus, Michal; Krecek, J

doi:10.1113/jphysiol.1963.sp007186

Cited by 43 publications

(14 citation statements)

References 11 publications

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“…Thus, acceleration of the development of the "mature" response to blood volume expansion in fast growing rats indicates an association of the response with body size rather than with the chronologic age of the animal (I). This conclusion is consistent with the anatomic development of the kidney, which is complete by approximately 25 d, but is not affected by alteration in the time of weaning (16,17). Thus, maturation of the renal response to acute volume expansion in the rat may involve changes in the release (18) or renal action of ANP (19) during the preweaning period.…”

Section: Discussionsupporting

confidence: 74%

Role of Atrial Natriuretic Peptide in the Response to Blood Volume Expansion in the Weanling Rat

et al. 1990

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ABSTRACT. After acute blood volume expansion (BVE) in the rat, diuresis and natriuresis are reported to be minimal in rats 20 to 30 d of age, but increase to mature levels by 40 d of age. To evaluate the role of atrial natriuretic peptide (ANP) and its renal action in BVE, anesthetized Sprague-Dawley rats were studied at 25 to 30 (group I) and 45 to 50 d of age (group 11). Hematocrit, mean arterial pressure, glomerular filtration rate, urine flow rate, urine sodium excretion, urine cyclic GMP excretion, and plasma ANP concentration ([ANP]) were measured before and after infusion of donor littermate whole blood, 2.5% body wt (BVE), and in time controls (no BVE) in each group. Baseline hematocrit, mean arterial pressure, and glomerular filtration rate were greater in group I1 than group I, but urine flow rate, urine sodium excretion, urine cyclic GMP excretion, and [ANP] did not differ. BVE caused a prompt increase in urine flow rate, urine sodium excretion, and [ANP], but not urine cyclic GMP excretion, in both groups, but there was no difference in the response between groups. Additional groups of rats of the same ages as groups I and I1 studied using a protocol similar to that of a previous report also showed the "mature" diuretic and natriuretic response even in the younger animals. We conclude that there is no further maturation of the renal response to acute BVE in the euvolemic rat after 25 d of age. The increase in [ANP] after acute BVE in the immature weanling rat is consistent with a role for ANP in mediation of the renal response. (Pediatr Res 27: 396-400, 1990) Abbreviations ANP, atrial natriuretic peptide cGMP, guanosine 3'. 5'-cyclic monophosphate FEN,, fractional excretion of sodium MAP, mean arterial pressure Compared to the adult, the immature kidney responds to acute volume expansion with attenuated diuresis and natriuresis (1-4). Since the discovery of ANP, there has been considerable interest in defining the role of ANP in volume regulation during

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Section: Discussionsupporting

confidence: 74%

Role of Atrial Natriuretic Peptide in the Response to Blood Volume Expansion in the Weanling Rat

et al. 1990

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“…It is unlikely that dietary modifications influenced the maturation of aldose reductase activity because mRNA levels were already high at 6-14 d, well before the rats attempt to wean. Previous studies have confirmed that premature weaning at 14-16 d failed to perceptively affect the histological structure of the kidney (29) or induce early maturational increases in urine osmolality after 24 h of fluid and food deprivation (9). We did see increased aldose reductase mRNA (following restriction of suckling) in terminal IMCDs from rats of all ages, but these increases were only significant in 14 and 17 d old rats.…”

Section: Discussionmentioning

confidence: 80%

Maturation of aldose reductase expression in the neonatal rat inner medulla.

Schwartz

Zavilowitz²,

Radice³

et al. 1992

J. Clin. Invest.

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Newborns are less able to concentrate urine than adults are. With development of the concentrating system and a hypertonic medullary interstitium, there is a need to generate intracellular osmolytes such as sorbitol, which is produced in a reaction catalyzed by the enzyme aldose reductase. We sought to discriminate between two possible mechanisms of aldose reductase induction during development: (a) a response to an osmotic stimulus generated by the concentrating mechanism; or (b) part of the genetic program for development of the kidney. We measured the change in aldose reductase mRNA and activity in terminal inner medullary collecting ducts (IMCDs) microdissected from Sprague-Dawley rats during the first month of life. Aldose reductase mRNA was assayed by Northern analysis of total RNA from inner medulla and by detection of the reverse transcription-polymerase chain reaction (RT-PCR) product obtained from single IMCDs using aldose reductase-specific primers. Aldose reductase activity was measured in IMCDs taken from the same rats using a fluorescent microassay. Newborn rat IMCDs had minimal aldose reductase mRNA or activity, however mRNA was readily detected in IMCDs from rats older than 3 d of age, with peak expression occurring at 1-3 wk of age before decreasing to adult levels. In contrast, the mRNA level for a housekeeping metabolic enzyme, malate dehydrogenase, did not change during maturation. Aldose reductase enzyme activity was readily detectable by 6 d of age, peaked at 20 d, then decreased to adult levels. Urine osmolality remained < 600 mosmol/kg until 16 d, then increased to > 1,100 mosmol/kg after 20 d. Thus, aldose reductase mRNA and activity increased before urinary osmolality reached 870 mosmol/kg. Because urine osmolality may not be indicative of inner medullary osmolality and because mother's milk may provide excessive free water to the pups under 3 wk ofage, halfofthe animals in several litters were separated from their mothers for 1 d and inner medullary osmolality, in addition to urine osmolality, was measured by vapor pressure osmometry, while aldose reductase mRNA was assessed densitometrically in IMCDs after RT-PCR. Although fluid restriction resulted in a near doubling

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“…The experiments reported here indicate something of the complexity of the relationship of mitosis to differentiation especially if mitosis in development (see also Boss et al, 1963) is considered together with artificial stimulation in adults.…”

Section: Discussionmentioning

confidence: 84%

The provocation of mitosis by 6-styryl-2,4,5-triamino-pyrimidine

Boss¹

1968

Br J Cancer

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The structure of the kidney in relation to age and diet in white rats during the weaning period

Cited by 43 publications

References 11 publications

Role of Atrial Natriuretic Peptide in the Response to Blood Volume Expansion in the Weanling Rat

Role of Atrial Natriuretic Peptide in the Response to Blood Volume Expansion in the Weanling Rat

Maturation of aldose reductase expression in the neonatal rat inner medulla.

The provocation of mitosis by 6-styryl-2,4,5-triamino-pyrimidine

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