Single nephron glomerular filtration rate ratios of superficial, intercortical and juxtamedullary nephrons in rats during development

Dlouhá, H; Bíbr, B; Ježek, Jan; Zicha, Josef

doi:10.1007/bf00585891

Cited by 9 publications

(2 citation statements)

References 10 publications

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“…1) (291; 336). The localization and structural heterogeneity of superficial and juxtamedullary nephrons have been extensively investigated since the 1960s (68; 68; 84; 115; 182; 221; 248; 249; 335; 350; 411; 431; 439). Studies using light and high resolution electron microscopes have demonstrated that nephrons in rodents and humans differ not only in their glomerular localization, but also in their structural characteristics.…”

Section: Classification Of Nephronsmentioning

confidence: 99%

Proximal Nephron

Zhuo,

2013

Comprehensive Physiology

167

140

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The kidney plays a fundamental role in maintaining body salt and fluid balance and blood pressure homeostasis through the actions of its proximal and distal tubular segments of nephrons. However, proximal tubules are well recognized to exert a more prominent role than distal counterparts. Proximal tubules are responsible for reabsorbing approximately 65% of filtered load and most, if not all, of filtered amino acids, glucose, solutes, and low molecular weight proteins. Proximal tubules also play a key role in regulating acid-base balance by reabsorbing approximately 80% of filtered bicarbonate. The purpose of this review article is to provide a comprehensive overview of new insights and perspectives into current understanding of proximal tubules of nephrons, with an emphasis on the ultrastructure, molecular biology, cellular and integrative physiology, and the underlying signaling transduction mechanisms. The review is divided into three closely related sections. The first section focuses on the classification of nephrons and recent perspectives on the potential role of nephron numbers in human health and diseases. The second section reviews recent research on the structural and biochemical basis of proximal tubular function. The final section provides a comprehensive overview of new insights and perspectives in the physiological regulation of proximal tubular transport by vasoactive hormones. In the latter section, attention is particularly paid to new insights and perspectives learnt from recent cloning of transporters, development of transgenic animals with knockout or knockin of a particular gene of interest, and mapping of signaling pathways using microarrays and/or physiological proteomic approaches.

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Section: Classification Of Nephronsmentioning

confidence: 99%

Proximal Nephron

Zhuo,

2013

Comprehensive Physiology

167

140

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“…32 Only at that age is the development of the kidney function accomplished by achievement of the adult pattern of distribution of the single-nephron glomerular filtration (SNGFR) . 33 Therefore, SNGFR distribution was estimated in developing Brattleboro rats. Baines 34 modification of Hansen's [14C]ferrocyanide single-injection method was used and the ratios of superficial to juxtamedullary (S/ J) and intercortical to juxtamedullary (I/ J ) nephrons were determined.…”

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Postnatal Development and Diabetes Insipidus in Brattleboro Rats

Dlouhá¹,

Krecek²,

Zicha³

1982

Annals of the New York Academy of Sciences

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The syndrome of hereditary diabetes insipidus of hypothalamic origin has been described in adult rats.' The task of this paper is to ascertain whether this syndrome is also present in young animals and at what age it begins to be manifest. Inasmuch as this type of diabetes insipidus is caused by the defect of vasopressin synthesis, it is obvious that its symptoms cannot be disclosed before the age at which the presence of vasopressin is detected in normal rats.Neurons of the vasopressin-synthesizing hypothalamic nuclei (i.e., n. supraopticus and n. paraventricularis) are found between days 13-17 of fetal life in rats2, Radioimmunoassayable vasopressin was observed in the rat brain at day 14 and in the pituitary at day 16 of fetal life.6 In his pioneer study from 1947 Hans Heller estimated the vasopressin content in the neurohypophysis to be less than 3 mU and more than 1.5 mU/gland in 1-day-old rats. This is in perfect accordance with recent data obtained using radioimmun~assay.~The osmoregulatory role of neurohypophysis is effectuated mainly by its influence on kidney function. It is mediated by the blood transfer of vasopressin. However, no antidiuretic activity was found in the blood plasma of normally hydrated rats until the age of four weeks.8 Antidiuretic activity corresponding to 4-5 pU/ml was observed in plasma of 23-day-old rats after water deprivation for six hours. Very low but detectable (about 1 pU/ml) activity appeared in plasma of 10-day-old rats loaded by a 3% salt sol~tion.~ From these data it could be predicted that the first signs of impaired concentrating ability of the kidney, accompanied by polyuria and polydipsia, ought to appear in homozygous Brattleboro rats in the course of the second to fourth postnatal week.Young Brattleboro rats were exposed to water deprivation for six hours at the ages of 10, 14, 18, and 22 days. Urine was obtained by perineal stimulation.10-and 14-day-old animals were kept without mother at 30" C, the older ones at 25" C. Urine osmolarity was determined by means of the Knauer osmometer. As shown in FIGURE 1, values of urinary osmolarity in homoand heterozygotes did not differ in 10-and 14-day-old rats whereas two distinct populations were found in 18-and 22-day-old animals. It was assumed that the group with lower osmolarity consisted of insipidic animals while the group with higher urinary osmolarity were animals without diabetes insipidus. This assumption was confirmed by measurement of water intake carried out at the age of 27 days. Water intake did not exceed 25 ml-100 g l -2 4 h-l in individuals with high urine osmolarity and it exceeded 50% of the body weight in animals with low urinary osmolarity.lo Hence, the difference in concentrating

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