Functional segmentation of the mammalian nephron

1981 ◽  
Vol 241 (3) ◽  
pp. F203-F218 ◽  
Author(s):  
H. R. Jacobson
Keyword(s):  
Biochemical Analysis ◽  
Epithelial Transport ◽  
Cell Types ◽  
Transport Processes ◽  
Renal Physiology ◽  
Hormonal Responses ◽  
Nephron Segments ◽  
New Information ◽  
Nephron Segment

Although each of the major experimental techniques applied to the study of renal physiology has provided its fair share of new information, the technique of in vitro microperfusion of nephron segments is notable for two major contributions. First, it has supplied a more direct and controlled means of studying epithelial transport processes, some of which already have helped us to understand certain aspects of kidney function and others of which have yet to find their application in unraveling the mysteries of the kidney. Second, in the process of delineating these transport characteristics, it has served to emphasize the epithelial specialization present in the kidney, providing functional counterparts to the already recognized anatomic heterogeneity present in the kidney. In this second role microperfusion has spawned the application of biochemical analysis of the hormonal responses of various nephron segments and contributed to the impetus for work in culturing the various cell types present in each nephron segment. This review outlines the functional characteristics of the 11 major segments of the nephron, incorporating what has been learned from some of the biochemical work on hormone response and correlating the latter with transport events.

scholarly journals Modulation of cell membrane area in renal collecting tubules by corticosteroid hormones.

1979 ◽  
Vol 81 (2) ◽  
pp. 439-445 ◽  
Author(s):  
J B Wade ◽  
R G O'Neil ◽  
J L Pryor ◽  
E L Boulpaep
Keyword(s):  
Cell Membrane ◽  
Epithelial Transport ◽  
Basolateral Membrane ◽  
Cell Types ◽  
Cell Number ◽  
Membrane Area ◽  
Corticosteroid Hormones ◽  
Nephron Segment ◽  
Desoxycorticosterone Acetate ◽  
Collecting Tubules

Isolated renal cortical collecting tubules obtained from rabbits treated chronically with desoxycorticosterone acetate (DOCA) have been found to possess elevated transepithelial potential differences and a greatly increased capacity for ion transport. Structural exmination of tubules from rabbits exposed to either DOCA or dexamethasone for 11--18 d reveals a marked increase in basolateral cell membrane area in these tubules. Morphometric analysis shows that this effect is specifically on the basolateral membrane area of only one of the two cell types found in this nephron segment. Increases of greater than 140% and 90% are found for the basolateral membrane area of the principal cells for DOCA and dexamethasone, respectively, but no change could be detected in the basolateral membrane area of the intercalated cells found in this nephron segment. No siginificant changes were found in luminal membrane area, cell number, or cell volume for either cell type. These observations demonstrate that significant changes in membrane area can occur in differentiated epithelia and suggest that this may be an important mechanism for modulating epithelial transport capacity.

Renal potassium transport: contributions of individual nephron segments and populations

1978 ◽  
Vol 235 (6) ◽  
pp. F515-F527 ◽  
Author(s):  
F. S. Wright ◽  
G. Giebisch
Keyword(s):  
Collecting Duct ◽  
Distal Tubule ◽  
Transport Processes ◽  
Potassium Excretion ◽  
Cortical Collecting Duct ◽  
Distal Nephron ◽  
Acid Base Balance ◽  
Cellular Mechanisms ◽  
Nephron Segments

General features of the processes that contribute to renal potassium excretion are understood from clearance, stop-flow, micropuncture, and in vitro microperfusion experiments. However, the complex architecture of the kidney has made it difficult to examine individual nephron segments in all parts of the kidney. Accordingly, the extent to which distinguishable nephron populations, such as superficial and deep, may differ in their contributions to overall potassium excretion are not known. Also, the nature of transport processes across the successive segments of the nephrons (including not only the underlying cellular mechanisms, but even the direction of transport) is not known for all segments in any one nephron population. Excreted potassium is derived both from filtered potassium that escapes reabsorption and from secreted potassium. The filtered portion is large in amphibians and may be larger than generally recognized in mammals. The remainder is secreted primarily by distal nephron segments (distal tubule and cortical collecting duct). Potassium is also secreted into descending limbs of Henle loops; apparently this fraction is recycled from collecting ducts, and so does not represent an additional quantity of potassium transferred from blood to tubule fluid. Systemic factors that affect potassium excretion (potassium intake, sodium chloride intake, mineralocorticoid hormone levels, acid-base balance, and diuretic treatments) do so by modifying the net uptake of potassium from blood to cell and by altering the rate of fluid flow through the distal nephron. Under most circumstances, the distal nephron in the cortex appears to secrete potassium and the medullary collecting duct reabsorbs potassium. Although it is clear that successive nephron segments transport potassium in different ways, evidence to date does not indicate that potassium is handled differently by superficial nephrons compared to nephrons whose glomeruli lie in the deeper levels of the cortex.

scholarly journals Vibrodissociation method for isolation of defined nephron segments from human and rodent kidneys

2019 ◽  
Vol 317 (5) ◽  
pp. F1398-F1403 ◽  
Author(s):  
Elena Isaeva ◽  
Mykhailo Fedoriuk ◽  
Ruslan Bohovyk ◽  
Christine A. Klemens ◽  
Sherif Khedr ◽  
...  
Keyword(s):  
Energy Homeostasis ◽  
Current Knowledge ◽  
Cell Types ◽  
Specific Cell ◽  
Renal Tubules ◽  
Gene Markers ◽  
Nephron Segments ◽  
Nephron Segment ◽  
Cell Energy ◽  
Health And Disease

Our current knowledge of the properties of renal ion channels responsible for electrolytes and cell energy homeostasis mainly relies on rodent studies. However, it has not been established yet to what extent their characteristics can be generalized to those of humans. The present study was designed to develop a standardized protocol for the isolation of well-preserved glomeruli and renal tubules from rodent and human kidneys and to assess the functional suitability of the obtained materials for physiological studies. Separation of nephron segments from human and rodent kidneys was achieved using a novel vibrodissociation technique. The integrity of isolated renal tubules and glomeruli was probed via electrophysiological analysis and fluorescence microscopy, and the purity of the collected fractions was confirmed using quantitative RT-PCR with gene markers for specific cell types. The developed approach allows rapid isolation of well-preserved renal tubules and glomeruli from human and rodent kidneys amenable for electrophysiological, Ca2+ imaging, and omics studies. Analysis of the basic electrophysiological parameters of major K+ and Na+ channels expressed in human cortical collecting ducts revealed that they exhibited similar biophysical properties as previously reported in rodent studies. Using vibrodissociation for nephron segment isolation has several advantages over existing techniques: it is less labor intensive, requires little to no enzymatic treatment, and produces large quantities of well-preserved experimental material in pure fractions. Applying this method for the separation of nephron segments from human and rodent kidneys may be a powerful tool for the indepth assessment of kidney function in health and disease.

Regulation of osmotic water permeability during differentiation of inner medullary collecting duct

1991 ◽  
Vol 260 (5) ◽  
pp. F710-F716 ◽  
Author(s):  
E. Siga ◽  
M. F. Horster
Keyword(s):  
Water Permeability ◽  
Epithelial Transport ◽  
Collecting Duct ◽  
Osmotic Water Permeability ◽  
Osmotic Concentration ◽  
Inner Medullary Collecting Duct ◽  
Osmotic Water ◽  
Nephron Segment ◽  
Medullary Collecting Duct

Urinary osmotic concentration capacity during renal ontogeny is subject to changes of medullary cytoarchitecture and of segmental epithelial transport characteristics. Osmotic equilibrium between interstitial and tubular fluid of the terminal nephron segment in response to vasopressin is an absolute essential of maximal urinary osmotic concentration. The regulation of osmotic water permeability (Pf) in this terminal epithelial segment during ontogenetic differentiation has not been documented. The inner medullary collecting duct (IMCD), the terminal 40% of total segmental length, was dissected at two stages of postnatal ontogenetic differentiation from immature (days 7-15) and from mature (days 33-37) rat kidneys and perfused in vitro. Pf (micron/s) was measured (bath hyperosmotic) in the absence and presence of arginine vasopressin (AVP, 230 pM). Basal Pf was 32.3 +/- 4.03 (n = 26) in the immature IMCD (IMCDi) and 111.5 +/- 20.6 (n = 15) in the mature segment (IMCDm). AVP increased Pf in IMCDi from 46.4 +/- 10.5 to 102 +/- 25.7 micron/s, whereas in IMCDm the AVP-dependent change of Pf was from 104.2 +/- 41.2 to 693 +/- 176 micron/s. AVP (2,300 pM) did not further increase Pf in IMCDi. Forskolin (50 microM) changed Pf in IMCDi from 34.9 +/- 6.3 to 104.1 +/- 16 micron/s; the corresponding change in IMCDm was from 150 +/- 32 to 985.8 +/- 133 micron/s. An analogue of adenosine 3',5'-cyclic monophosphate (cAMP; 10(-3) M) increased Pf in IMCDi from 35.5 +/- 11.4 to 138.5 +/- 32.6 and in IMCDm from 79.6 +/- 32.3 to 702.2 +/- 283 micron/s.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Sensitivity of Acute Leukemia Cells to Cytarabine Is a Correlate of Cellular es Nucleoside Transporter Site Content Measured by Flow Cytometry With SAENTA-Fluorescein

Blood ◽  
1997 ◽  
Vol 90 (1) ◽  
pp. 346-353 ◽  
Author(s):  
Wendy P. Gati ◽  
Alan R.P. Paterson ◽  
Loree M. Larratt ◽  
A. Robert Turner ◽  
Andrew R. Belch
Keyword(s):  
Flow Cytometry ◽  
Acute Leukemia ◽  
Cell Types ◽  
Transport Processes ◽  
Nucleoside Transport ◽  
Leukemia Cells ◽  
Nucleoside Transporter ◽  
Flow Cytometric Method ◽  
Ic50 Values

Abstract Cytarabine (araC) is converted to araC 5′-triphosphate after entering leukemia cells as a substrate for nucleoside transport processes. This study tested the relationship between araC cytotoxicity, measured in an in vitro tetrazolium dye reduction assay of cell viability, and the cellular abundance of es nucleoside transport elements, assayed by a flow cytometric method that used the es-specific stain, 5-(SAENTA-x8)-fluorescein (5-(Sx8)-F), in cultured leukemia cells and in myeloblasts and lymphoblasts (blasts) from leukemia patients. Cellular es site abundance (Bmax value for 5-(Sx8)-F binding) varied sixfold among nine leukemic myeloblast samples from patients. In cultured OCI/AML-2 myeloblasts and CCRF-CEM T-lymphoblasts, and in fresh leukemic blasts, es sites were fractionally blocked by treatment with graded concentrations of nitrobenzylthioinosine (NBMPR), an inhibitory es site ligand, to simulate the variation in es expression found in leukemic blasts from patients with acute myeloid leukemia. When the cytotoxicity of a single concentration of araC was determined in NBMPR-treated leukemia cells, cell kill correlated closely with the intensity of 5-(Sx8)-F fluorescence (r = .92 to .99), a measure of the cell surface abundance of functional es nucleoside transporter sites. Concentrations of NBMPR that achieved half-maximal reduction (4.3 to 12 nmol/L) of cellular 5-(Sx8)-F fluorescence (measured by flow cytometry) approximated IC50 values (1 to 10 nmol/L) previously found for inhibition by NBMPR of es-mediated nucleoside fluxes in several cell types, supporting the view that 5-(Sx8)-F interacted with the es transporter. The correlation of araC cytotoxicity and the Bmax for 5-(Sx8)-F binding to es sites in cultured leukemia cells and in leukemic blasts from acute leukemia patients (r = .95) suggests that the flow cytometry assay of es capacity may be useful in predicting clinical response to araC.

scholarly journals Sensitivity of Acute Leukemia Cells to Cytarabine Is a Correlate of Cellular es Nucleoside Transporter Site Content Measured by Flow Cytometry With SAENTA-Fluorescein

Blood ◽  
1997 ◽  
Vol 90 (1) ◽  
pp. 346-353 ◽  
Author(s):  
Wendy P. Gati ◽  
Alan R.P. Paterson ◽  
Loree M. Larratt ◽  
A. Robert Turner ◽  
Andrew R. Belch
Keyword(s):  
Flow Cytometry ◽  
Acute Leukemia ◽  
Cell Types ◽  
Transport Processes ◽  
Nucleoside Transport ◽  
Leukemia Cells ◽  
Nucleoside Transporter ◽  
Flow Cytometric Method ◽  
Ic50 Values

Cytarabine (araC) is converted to araC 5′-triphosphate after entering leukemia cells as a substrate for nucleoside transport processes. This study tested the relationship between araC cytotoxicity, measured in an in vitro tetrazolium dye reduction assay of cell viability, and the cellular abundance of es nucleoside transport elements, assayed by a flow cytometric method that used the es-specific stain, 5-(SAENTA-x8)-fluorescein (5-(Sx8)-F), in cultured leukemia cells and in myeloblasts and lymphoblasts (blasts) from leukemia patients. Cellular es site abundance (Bmax value for 5-(Sx8)-F binding) varied sixfold among nine leukemic myeloblast samples from patients. In cultured OCI/AML-2 myeloblasts and CCRF-CEM T-lymphoblasts, and in fresh leukemic blasts, es sites were fractionally blocked by treatment with graded concentrations of nitrobenzylthioinosine (NBMPR), an inhibitory es site ligand, to simulate the variation in es expression found in leukemic blasts from patients with acute myeloid leukemia. When the cytotoxicity of a single concentration of araC was determined in NBMPR-treated leukemia cells, cell kill correlated closely with the intensity of 5-(Sx8)-F fluorescence (r = .92 to .99), a measure of the cell surface abundance of functional es nucleoside transporter sites. Concentrations of NBMPR that achieved half-maximal reduction (4.3 to 12 nmol/L) of cellular 5-(Sx8)-F fluorescence (measured by flow cytometry) approximated IC50 values (1 to 10 nmol/L) previously found for inhibition by NBMPR of es-mediated nucleoside fluxes in several cell types, supporting the view that 5-(Sx8)-F interacted with the es transporter. The correlation of araC cytotoxicity and the Bmax for 5-(Sx8)-F binding to es sites in cultured leukemia cells and in leukemic blasts from acute leukemia patients (r = .95) suggests that the flow cytometry assay of es capacity may be useful in predicting clinical response to araC.

Ultrastructural Changes in Three Different Mammalian Cells Following Ultraviolet Laser Irradiation

1972 ◽  
Vol 30 ◽  
pp. 350-351
Author(s):  
K. Shankar Narayan ◽  
Kailash C. Gupta ◽  
Tohru Okigaki
Keyword(s):  
Ultraviolet Light ◽  
Mammalian Cells ◽  
Biological Effects ◽  
Survival Rates ◽  
Chinese Hamster ◽  
Cell Types ◽  
Differential Sensitivity ◽  
Ultrastructural Changes ◽  
Ultraviolet Laser

The biological effects of short-wave ultraviolet light has generally been described in terms of changes in cell growth or survival rates and production of chromosomal aberrations. Ultrastructural changes following exposure of cells to ultraviolet light, particularly at 265 nm, have not been reported.We have developed a means of irradiating populations of cells grown in vitro to a monochromatic ultraviolet laser beam at a wavelength of 265 nm based on the method of Johnson. The cell types studies were: i) WI-38, a human diploid fibroblast; ii) CMP, a human adenocarcinoma cell line; and iii) Don C-II, a Chinese hamster fibroblast cell strain. The cells were exposed either in situ or in suspension to the ultraviolet laser (UVL) beam. Irradiated cell populations were studied either "immediately" or following growth for 1-8 days after irradiation.Differential sensitivity, as measured by survival rates were observed in the three cell types studied. Pattern of ultrastructural changes were also different in the three cell types.

Ultrastructural observations on the in vitro cytoadherence of Plasmodium falciparum infected red blood cells

1990 ◽  
Vol 48 (3) ◽  
pp. 914-915
Author(s):  
D.J.P. Ferguson ◽  
A.R. Berendt ◽  
J. Tansey ◽  
K. Marsh ◽  
C.I. Newbold
Keyword(s):  
Plasmodium Falciparum ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Umbilical Vein ◽  
Cell Types ◽  
Amelanotic Melanoma ◽  
Cytoplasmic Process ◽  
Umbilical Vein Endothelial Cells

In human malaria, the most serious clinical manifestation is cerebral malaria (CM) due to infection with Plasmodium falciparum. The pathology of CM is thought to relate to the fact that red blood cells containing mature forms of the parasite (PRBC) cytoadhere or sequester to post capillary venules of various tissues including the brain. This in vivo phenomenon has been studied in vitro by examining the cytoadherence of PRBCs to various cell types and purified proteins. To date, three Ijiost receptor molecules have been identified; CD36, ICAM-1 and thrombospondin. The specific changes in the PRBC membrane which mediate cytoadherence are less well understood, but they include the sub-membranous deposition of electron-dense material resulting in surface deformations called knobs. Knobs were thought to be essential for cytoadherence, lput recent work has shown that certain knob-negative (K-) lines can cytoadhere. In the present study, we have used electron microscopy to re-examine the interactions between K+ PRBCs and both C32 amelanotic melanoma cells and human umbilical vein endothelial cells (HUVEC).We confirm previous data demonstrating that C32 cells possess numerous microvilli which adhere to the PRBC, mainly via the knobs (Fig. 1). In contrast, the HUVEC were relatively smooth and the PRBCs appeared partially flattened onto the cell surface (Fig. 2). Furthermore, many of the PRBCs exhibited an invagination of the limiting membrane in the attachment zone, often containing a cytoplasmic process from the endothelial cell (Fig. 2).

Role of the 807 C/T Polymorphism of the α2 Gene in Platelet GP Ia Collagen Receptor Expression and Function

1999 ◽  
Vol 81 (06) ◽  
pp. 951-956 ◽  
Author(s):  
J. Corral ◽  
R. González-Conejero ◽  
J. Rivera ◽  
F. Ortuño ◽  
P. Aparicio ◽  
...  
Keyword(s):  
Venous Thrombosis ◽  
Cell Types ◽  
Receptor Expression ◽  
Case Control Studies ◽  
Platelet Surface ◽  
Vitro Analysis ◽  
And Function ◽  
In Vitro Analysis

SummaryThe variability of the platelet GP Ia/IIa density has been associated with the 807 C/T polymorphism (Phe 224) of the GP Ia gene in American Caucasian population. We have investigated the genotype and allelic frequencies of this polymorphism in Spanish Caucasians. The T allele was found in 35% of the 284 blood donors analyzed. We confirmed in 159 healthy subjects a significant association between the 807 C/T polymorphism and the platelet GP Ia density. The T allele correlated with high number of GP Ia molecules on platelet surface. In addition, we observed a similar association of this polymorphism with the expression of this protein in other blood cell types. The platelet responsiveness to collagen was determined by “in vitro” analysis of the platelet activation and aggregation response. We found no significant differences in these functional platelet parameters according to the 807 C/T genotype. Finally, results from 3 case/control studies involving 302 consecutive patients (101 with coronary heart disease, 104 with cerebrovascular disease and 97 with deep venous thrombosis) determined that the 807 C/T polymorphism of the GP Ia gene does not represent a risk factor for arterial or venous thrombosis.

Epithelial Organotypic Cultures: A Viable Model to Address Mechanisms of Carcinogenesis by Epitheliotropic Viruses

2018 ◽  
Vol 18 (4) ◽  
pp. 246-255 ◽  
Author(s):  
Lara Termini ◽  
Enrique Boccardo
Keyword(s):  
Three Dimensional ◽  
Cell Types ◽  
Experimental Models ◽  
Biological Research ◽  
Specific Gene ◽  
Specific Cell ◽  
Organotypic Cultures ◽  
Skin Physiology

In vitro culture of primary or established cell lines is one of the leading techniques in many areas of basic biological research. The use of pure or highly enriched cultures of specific cell types obtained from different tissues and genetics backgrounds has greatly contributed to our current understanding of normal and pathological cellular processes. Cells in culture are easily propagated generating an almost endless source of material for experimentation. Besides, they can be manipulated to achieve gene silencing, gene overexpression and genome editing turning possible the dissection of specific gene functions and signaling pathways. However, monolayer and suspension cultures of cells do not reproduce the cell type diversity, cell-cell contacts, cell-matrix interactions and differentiation pathways typical of the three-dimensional environment of tissues and organs from where they were originated. Therefore, different experimental animal models have been developed and applied to address these and other complex issues in vivo. However, these systems are costly and time consuming. Most importantly the use of animals in scientific research poses moral and ethical concerns facing a steadily increasing opposition from different sectors of the society. Therefore, there is an urgent need for the development of alternative in vitro experimental models that accurately reproduce the events observed in vivo to reduce the use of animals. Organotypic cultures combine the flexibility of traditional culture systems with the possibility of culturing different cell types in a 3D environment that reproduces both the structure and the physiology of the parental organ. Here we present a summarized description of the use of epithelial organotypic for the study of skin physiology, human papillomavirus biology and associated tumorigenesis.

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