Effect of Saline Infusions on the Intrarenal Distribution of Glomerular Filtrate and Renal Blood Flow1

In the course of urine formation in mammalian kidneys over 90% of the glomerular filtrate moves from the tubular lumen into the peritubular capillaries by both active and passive transport mechanisms. In all of the morphologically distinct segments of the renal tubule, e.g. proximal tubule, loop of Henle and distal nephron, the tubular absorbate passes through a basement membrane which rests against the basilar surface of the epithelial cells. The basement membrane is in a strategic location to affect the geometry of the tubules and to influence the movement of tubular absorbate into the renal interstitium. In the present studies we have determined directly some of the mechanical and permeability characteristics of tubular basement membranes.

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Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

Nuklearmedizin ◽

10.1055/s-0037-1620616 ◽

1977 ◽

Vol 16 (03) ◽

pp. 100-103 ◽

Cited By ~ 1

Author(s):

C. Schümichen ◽

J. Waiden ◽

G. Hoffmann

Keyword(s):

Glomerular Filtration ◽

Renal Clearance ◽

Plasma Protein ◽

Kinetic Data ◽

Adult Rats ◽

Compound A ◽

Extravascular Space ◽

Tubular Cells ◽

Glomerular Filtrate ◽

Kinetics Of

SummaryThe kinetic data of two different 99mTc-Sn-pyrophosphate compounds (compound A and B) were evaluated in non-adult rats. Only compound A concentrated in bone. Both compounds dispersed rapidly in the intravascular as well as the extravascular space. The plasma protein bond of both compounds increased with time after injection and impaired both the renal clearance of both compounds and the bone clearance of compound A. The renal clearance of both compounds was somewhat above that of 5 1Cr-EDTA. It is concluded that compound A and B is mainly excreted by glomerular filtration. About one fourth of the glomerular filtrate of compound B is reabsorbed and accumulated by the tubular cells.

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Proposal for the administration of metformin in patients with chronic kidney disease

Orvosi Hetilap ◽

10.1556/oh.2012.29448 ◽

2012 ◽

Vol 153 (39) ◽

pp. 1527-1535 ◽

Cited By ~ 1

Author(s):

Zoltán Balogh ◽

János Mátyus

Keyword(s):

Lactic Acidosis ◽

Chronic Renal Disease ◽

Antidiabetic Agent ◽

First Line ◽

Oral Antidiabetic Agent ◽

Oral Antidiabetic ◽

Cardiovascular Morbidity And Mortality ◽

Glomerular Filtrate ◽

Life Threatening

Metformin is the first-line, widely used oral antidiabetic agent for the management of type 2 diabetes. There is increasing evidence that metformin use results in a reduction in cardiovascular morbidity and mortality, and might have anticancer activity. An extremely rare, but potentially life-threatening adverse effect of metformin is lactic acidosis, therefore, its use is traditionally contraindicated if the glomerular filtrate rate is below 60 mL/min. However, lactic acidosis is always associated with acute events, such as hypovolemia, acute cardiorespiratory illness, severe sepsis and acute renal or hepatic failure. Furthermore, administration of insulins and conventional antihyperglycemic agents increases the risk of severe hypoglycemic events when renal function is reduced. Therefore, the magnitude of the benefit of metformin use would outweigh potential risk of lactic acidosis in moderate chronic renal disease. After reviewing the literature, the authors give a proposal for the administration of metformin, according to the calculated glomerular filtrate rate. Orv.Hetil., 2012, 153, 1527–1535.

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Generation and characterization of iPSC-derived renal proximal tubule-like cells with extended stability

Scientific Reports ◽

10.1038/s41598-021-89550-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Vidya Chandrasekaran ◽

Giada Carta ◽

Daniel da Costa Pereira ◽

Rajinder Gupta ◽

Cormac Murphy ◽

...

Keyword(s):

Proximal Tubule ◽

Retinoic Acid Receptor ◽

Renal Proximal Tubule ◽

Whole Body ◽

Proper Function ◽

Genome Wide ◽

Glomerular Filtrate ◽

Proximal Tubular ◽

Induced Pluripotent

AbstractThe renal proximal tubule is responsible for re-absorption of the majority of the glomerular filtrate and its proper function is necessary for whole-body homeostasis. Aging, certain diseases and chemical-induced toxicity are factors that contribute to proximal tubule injury and chronic kidney disease progression. To better understand these processes, it would be advantageous to generate renal tissues from human induced pluripotent stem cells (iPSC). Here, we report the differentiation and characterization of iPSC lines into proximal tubular-like cells (PTL). The protocol is a step wise exposure of small molecules and growth factors, including the GSK3 inhibitor (CHIR99021), the retinoic acid receptor activator (TTNPB), FGF9 and EGF, to drive iPSC to PTL via cell stages representing characteristics of early stages of renal development. Genome-wide RNA sequencing showed that PTL clustered within a kidney phenotype. PTL expressed proximal tubular-specific markers, including megalin (LRP2), showed a polarized phenotype, and were responsive to parathyroid hormone. PTL could take up albumin and exhibited ABCB1 transport activity. The phenotype was stable for up to 7 days and was maintained after passaging. This protocol will form the basis of an optimized strategy for molecular investigations using iPSC derived PTL.

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An immunohistochemical study of aspartate, glutamate, and taurine in rat kidney.

Journal of Histochemistry & Cytochemistry ◽

10.1177/42.5.7908911 ◽

1994 ◽

Vol 42 (5) ◽

pp. 621-626 ◽

Cited By ~ 19

Author(s):

N Ma ◽

E Aoki ◽

R Semba

Keyword(s):

Amino Acids ◽

Renal Cortex ◽

Rat Kidney ◽

Renal Medulla ◽

Loop Of Henle ◽

Immunoperoxidase Method ◽

Collecting Tubules ◽

Convoluted Tubules ◽

Thin Portion ◽

Intrarenal Distribution

Biochemical studies have revealed considerable amounts of free amino acids in the kidney. We examined the intrarenal distribution of three amino acids (aspartate, glutamate, and taurine) in the rat kidney with an immunoperoxidase method. In the renal cortex, all three amino acids were concentrated in the renal corpuscles and in the epithelia of the collecting tubules. Immunostaining of the collecting tubules was more intense in the principal cells than in the intercalated cells. The distal convoluted tubules were also immunostained with aspartate- and glutamate- specific antibodies but not with the taurine-specific antibody. In the renal medulla, the immunoreactivity specific for aspartate and for glutamate was similar; it was weak in the thick portion of the loop of Henle and strong in the collecting tubules. Immunoreactivity specific for taurine was restricted to regions within the epithelia of the thin portion of the loop of Henle and the collecting tubules. The significance of the accumulated amino acids as osmoregulatory agents is discussed.

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The Mode of Excretion of Ammonia and Urea in Xenopus Laevis

Journal of Experimental Biology ◽

10.1242/jeb.38.4.695 ◽

1961 ◽

Vol 38 (4) ◽

pp. 695-705

Author(s):

J. B. BALINSKY ◽

E. BALDWIN

Keyword(s):

Xenopus Laevis ◽

Blood Concentration ◽

Concentration Ratio ◽

Ammonia Excretion ◽

Ammonia Concentration ◽

Mean Value ◽

Urea Excretion ◽

Wide Range ◽

Glomerular Filtrate ◽

The Mean

1. Eighty-two single determinations of ammonia and urea excretion by Xenopus laevis indicated that the percentage of ammonia varied from 40 to 80%, with a mean value of 62%. 2. Measurements of excretion on successive days after feeding showed that a large amount of ammonia was produced soon after feeding, but that ammonia excretion declined rapidly. Urea excretion, not so high initially, remained more or less constant until the third or fourth day, often exceeding ammonia excretion at that time. Thereafter, it also declined and the excretion of both substances reached a constant starvation level by the fifteenth day. 3. Both ammonia and urea excretion were equally affected by temperature. The Q10's were near 2 in the range 20-30° C., but greater in the range 10-20° C. 4. At least 86% of ammonia, and 81% of urea were excreted through the cloaca. 5. The mean 24 hr. urine output of Xenopus at 20% C. was 23.6 ml. per 100 g. body weight. 6. Although the blood ammonia concentration did not appear to be zero, the urine/blood concentration ratio of ammonia was greater than 100. The urine/blood concentration ratio of urea was not significantly different from unity, and constant over a very wide range of concentrations. 7. The above result is interpreted to indicate passive glomerular filtration of urea, and little or no tubular reabsorption of water. 8. It is suggested that ammonia is formed in the kidney, and actively secreted into the glomerular filtrate.

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