Effect of calcium on transport characteristics of cultured proximal renal cells

1985 ◽  
Vol 249 (3) ◽  
pp. F346-F355
Author(s):  
L. M. Sakhrani ◽  
N. Tessitore ◽  
S. G. Massry
Keyword(s):  
Phosphate Uptake ◽  
Cytosolic Calcium ◽  
Ruthenium Red ◽  
Extracellular Calcium ◽  
Transport Processes ◽  
Renal Cells ◽  
Sodium Uptake ◽  
Calcium Loading ◽  
Sodium Dependent ◽  
Acute Changes

We examined the effects of acute changes in extracellular and intracellular calcium on transport processes in primary culture of proximal rabbit renal cells. A change in extracellular calcium from 0 to 3 mM inhibited amiloride-sensitive sodium uptake by 30%, and this effect was maximal at 1 mM calcium. Other polyvalent cations (Mn2+, Mg2+, La3+, and Ba2+) produced quantitatively similar inhibition of amiloride-sensitive sodium uptake compared with calcium. An increase in cytosolic calcium produced by calcium loading (20 mM) or by A23187 (20 microM) resulted in an inhibition of 25-40% of amiloride-sensitive sodium uptake. Moreover, quinidine (10(-4)M) and ruthenium red (3 microM), agents presumed to increase cytosolic calcium, inhibited amiloride-sensitive sodium uptake by 20-60%. Both these agents also inhibited sodium-dependent phosphate uptake by 20% but had no effect on ouabain-sensitive 86Rb+ uptake or on sodium-dependent alpha-methylglucoside uptake. Our data indicate that increases in extracellular calcium inhibit amiloride-sensitive sodium uptake and increases in cytosolic calcium inhibit sodium-dependent phosphate and amiloride-sensitive sodium uptakes. The effect of extracellular calcium may be due to charge screening and/or binding to the negatively charged plasma membrane or due to alterations in membrane fluidity.

Quantitative requirement for ATP for active transport in isolated renal cells

1986 ◽  
Vol 251 (1) ◽  
pp. C120-C127 ◽  
Author(s):  
N. Tessitore ◽  
L. M. Sakhrani ◽  
S. G. Massry
Keyword(s):  
Atpase Activity ◽  
Active Transport ◽  
Phosphate Uptake ◽  
Quantitative Relationship ◽  
Similar Degree ◽  
Renal Cells ◽  
Stepwise Manner ◽  
Sodium Gradient ◽  
Sodium Dependent ◽  
86Rb Influx

We investigated the quantitative relationship between cellular ATP concentration and Na+-K+-ATPase activity as measured by ouabain-sensitive 86Rb influx in rabbit proximal renal cells. Cellular ATP was reduced in a stepwise manner by rotenone (10(-7) to 10(-5) M) and was increased by 10 mM adenosine. During these maneuvers, ouabain-sensitive 86Rb influx was linearly related to cellular ATP and did not saturate up to 9.9 mM ATP. In contrast, Na+-K+-ATPase activity in membranes prepared from these cells saturated at 2.0 mM ATP at various sodium (10-100 mM) and potassium (4-100 mM) concentrations. Sodium-dependent phosphate uptake and alpha-methylglucoside (alpha-MG) uptake were both inhibited to a similar degree when cellular ATP was reduced. We conclude that 1) the ATP requirement for saturation of Na+-K+-ATPase is higher in intact renal cells than in the membranes, and 2) the uptake of phosphate and alpha-MG are similarly influenced by reduction in ATP. This effect of ATP on phosphate and AMG uptake is most likely an indirect one and is secondary to changes in the sodium gradient across the cell.

Requirement for transmembrane sodium flux in maintenance of cytosolic calcium levels in rat Sertoli cells

1993 ◽  
Vol 264 (6) ◽  
pp. E863-E867 ◽  
Author(s):  
E. Gorczynska ◽  
D. J. Handelsman
Keyword(s):  
Sertoli Cells ◽  
Calcium Concentration ◽  
Cytosolic Calcium ◽  
Ruthenium Red ◽  
Extracellular Calcium ◽  
Isolated Cells ◽  
Acetoxymethyl Ester ◽  
Calcium Fluxes ◽  
Calcium Exchange ◽  
Extracellular Sodium

The prompt rise in cytosolic calcium induced by follicle-stimulating hormone (FSH) in rat Sertoli cells suggests a role for calcium in FSH signal transduction. To evaluate the requirement for sodium in transmembrane calcium fluxes in Sertoli cells, we measured intracellular calcium concentration under sodium-free conditions and during stimulation by monensin and veratridine, used to elevate cytosolic sodium. Cytosolic calcium levels were measured by dual-wavelength spectrofluorimetry using freshly isolated cells loaded with fura-2 acetoxymethyl ester. Whereas, removal of extracellular sodium lowered cytosolic calcium in unstimulated cells from 89 +/- 4 to 75 +/- 8 nM, treatment with monensin and veratridine increased cytosolic calcium to 142 +/- 19 and 126 +/- 13 nM, respectively. Without extracellular calcium, monensin still produced 47% of the rise in cytosolic calcium observed in the presence of extracellular calcium, indicating approximately equal contributions of calcium from intracellular and extracellular sources. Blockade of voltage-sensitive or/and voltage-insensitive calcium channels by verapamil and ruthenium red was unable to completely prevent the monensin-induced elevation of cytosolic calcium. In addition tetrodotoxin failed to block the FSH-induced rise in cytosolic calcium. These observations, together with the considerable reduction in monensin-induced rise in cytosolic calcium under extracellular sodium-free condition, support the hypothesis that sodium-calcium exchange rather than the specific calcium or sodium channels regulate basal and monensin-induced transmembrane sodium and calcium fluxes in Sertoli cells.

scholarly journals Cooperative Activation of Cultured Vagal Afferent Neurons by Leptin and Cholecystokinin

Endocrinology ◽  
2004 ◽  
Vol 145 (8) ◽  
pp. 3652-3657 ◽  
Author(s):  
J. H. Peters ◽  
A. B. Karpiel ◽  
R. C. Ritter ◽  
S. M. Simasko
Keyword(s):  
Primary Cultures ◽  
Cytosolic Calcium ◽  
Extracellular Calcium ◽  
Vagal Afferents ◽  
Afferent Neurons ◽  
Adult Rat ◽  
Nodose Ganglia ◽  
Vagal Afferent ◽  
Acute Changes ◽  
And Control

Abstract To test the hypothesis that leptin can directly activate vagal afferent neurons, we used fluorescence imaging to detect acute changes in cytosolic calcium after leptin application to primary cultures of vagal afferent neurons dissociated from adult rat nodose ganglia. We found that approximately 40% of vagal afferent neurons exposed to leptin (40 ng/ml) responded with rapid and reversible increases in cytosolic calcium. These responses were dependent upon extracellular calcium. As previously reported, about 35% of vagal afferents increase cytosolic calcium in response to the gut-peptide cholecystokinin (CCK). A majority (74%) of neurons that responded to CCK also exhibited increases in cytosolic calcium in response to leptin. In addition, synergistic increases in cytosolic calcium were observed when leptin and CCK were applied in combination. These results demonstrate that leptin acts directly on vagal afferent neurons to trigger acute influxes of extracellular calcium. Our results also suggest cooperation between leptin and CCK in the activation of some vagal afferent neurons. Acute activation of vagal afferents by leptin alone and in combination with CCK may contribute to modulation of visceral reflexes and control of food intake.

Protein kinase A, cytosolic calcium, and phosphate uptake in human proximal renal cells

1989 ◽  
Vol 257 (4) ◽  
pp. F631-F638
Author(s):  
J. P. Middleton ◽  
C. B. Dunham ◽  
J. J. Onorato ◽  
D. A. Sens ◽  
V. W. Dennis
Keyword(s):  
Protein Kinase ◽  
Phosphate Uptake ◽  
Human Kidney ◽  
Cytosolic Calcium ◽  
Intracellular Camp ◽  
Renal Cells ◽  
Camp Pathway ◽  
Half Maximal Effective Concentration ◽  
Dependent Protein ◽  
Short Term Culture

Phosphate uptake by proximal renal cells derived from the human kidney occurs by a saturable process that is approximately 85% dependent on the presence of sodium. Kinetic analysis is consistent with two distinct transport events with Km of 0.08 and 0.63 mM and Vmax of 3.4 and 11.0 nmol.mg-1.3 min-1, respectively. Parathyroid hormone (PTH), isoproterenol, and prostaglandin E2 (PGE2) increased cellular adenosine 3',5'-cyclic monophosphate (cAMP). PTH-stimulated cAMP prevented binding of the photolabel 8-azido[32P]cAMP with a half-maximal effective concentration (EC50) of 1 nM PTH, 30-fold lower than the EC50 for intracellular cAMP accumulation. These data are qualitatively similar to those observed in OK cells. PTH did not inhibit phosphate uptake in human cells, although it activated cAMP-dependent protein kinase and increased cytosolic calcium. Thus phosphate uptake in human proximal renal cells maintained in short-term culture is unresponsive to PTH in spite of increased cytosolic calcium and activation of the cAMP pathway.

Sevoflurane but not propofol provided dual effects of cell survival in human neuroblastoma SH-SY5Y cells

2021 ◽  
Vol 18 ◽  
Author(s):  
Xue Gao ◽  
Xiu Wang ◽  
Lei Zhang ◽  
Ge Liang ◽  
Rachel Mund ◽  
...  
Keyword(s):  
Cell Survival ◽  
Prolonged Exposure ◽  
Calcium Influx ◽  
Cell Damage ◽  
Cytosolic Calcium ◽  
Extracellular Calcium ◽  
Mitochondrial Calcium ◽  
General Anesthetics ◽  
Wild Type ◽  
Human Neuroblastoma

Background: We have hypothesized that the most commonly used intravenous (propofol) and inhalational (sevoflurane) general anesthetics affect cell survival concentration and duration dependently with different potency associated with their differential potency to affect intracellular calcium homeostasis. Methods: Human neuroblastoma SH-SY5Y cells stably transfected with either wild type or M146L mutant human presenilin 1 were cultured and exposed to equipotent of propofol or sevoflurane. Cell viability, cytosolic and mitochondrial calcium were measured. Results: Sevoflurane but not propofol, at clinically relevant concentrations and durations, promoted cell survival. Prolonged exposure (24 hours) of 1% sevoflurane resulted in significant cell damage in both types of cells. Both sevoflurane and propofol had significantly higher cell response rates to the elevation of cytosolic calcium or mitochondrial calcium in the presence of extracellular calcium. With the contribution of calcium influx, sevoflurane but not equipotent 1 MAC propofol, caused a significantly greater increase in peak and overall calcium in Alzheimer’s mutation cell than in wild type cells, but significantly more increase in overall mitochondrial calcium concentrations in wild type than mutation cells. In the absence of extracellular calcium influx, sevoflurane, but not propofol, caused more significant elevations of overall mitochondrial calcium concentration in mutation cells than control cells. Conclusion: Calcium influx contributed to the general anesthetics mediated elevation of cytosolic or mitochondrial calcium, which is especially true for propofol. Sevoflurane has a greater potency to either promote or inhibit cell survival than propofol, which may be associated with its ability to affect cytosolic or mitochondrial calcium.

Modulation of frequency and height of cytosolic calcium spikes by plasma membrane anion channels in guard cells

2021 ◽  
Author(s):  
Md Tahjib-Ul-Arif ◽  
Shintaro Munemasa ◽  
Toshiyuki Nakamura ◽  
Yoshimasa Nakamura ◽  
Yoshiyuki Murata
Keyword(s):  
Plasma Membrane ◽  
Stomatal Closure ◽  
Anion Channel ◽  
Guard Cells ◽  
Cytosolic Calcium ◽  
Peak Height ◽  
Extracellular Calcium ◽  
Wild Type ◽  
Anion Channels ◽  
In The Wild

Abstract Cytosolic calcium ([Ca2+]cyt) elevation activates plasma membrane anion channels in guard cells, which is required for stomatal closure. However, involvement of the anion channels in the [Ca2+]cyt elevation remains unclear. We investigated the involvement using Arabidopsis thaliana anion channel mutants, slac1-4 slah3-3 and slac1-4 almt12-1. Extracellular calcium induced stomatal closure in the wild-type plants but not in the anion channel mutant plants whereas extracellular calcium induced [Ca2+]cyt elevation both in the wild-type guard cells and in the mutant guard cells. The peak height and the number of the [Ca2+]cyt spike were lower and larger in the slac1-4 slah3-3 than in the wild-type and the height and the number in the slac1-4 almt12-1 were much lower and much larger than in the wild-type. These results suggest that the anion channels are involved in the regulation of [Ca2+]cyt elevation in guard cells.

Comparative analysis of ontogenic changes in renal and intestinal biotin transport in the rat

2003 ◽  
Vol 284 (4) ◽  
pp. F737-F742 ◽  
Author(s):  
Svetlana M. Nabokina ◽  
Veedamali S. Subramanian ◽  
Hamid M. Said
Keyword(s):  
Age Groups ◽  
Membrane Vesicles ◽  
Transport Processes ◽  
Water Soluble ◽  
Kidney Cortex ◽  
Intestinal Epithelial ◽  
Adult Rats ◽  
Intestinal Epithelia ◽  
Sodium Dependent ◽  
Uptake Process

Biotin, an essential water-soluble micronutrient, cannot be synthesized by mammals; rather, it is obtained from exogenous sources via uptake by intestinal epithelia. Renal epithelia reclaim the vitamin that is filtered in the glomeruli. Both epithelia take up biotin via the sodium-dependent multivitamin transporter (SMVT). Little is known about ontogenic regulation of the renal and intestinal biotin transport processes and about the mechanism(s) involved in any such regulation. In this study, we sought to examine and compare ontogenic aspects of the renal and intestinal biotin uptake processes using purified brush-border membrane vesicles (BBMV) isolated from the kidney cortex and jejunum of suckling and adult rats. Clear ontogenic changes were observed in the intestinal biotin uptake process, which were mediated via changes in V max and apparent K m. Parallel changes were also seen in protein, mRNA, and transcription rate of SMVT as indicated by results of Western blotting, RT-PCR, and nuclear run-on assays, respectively. In contrast, biotin uptake by renal BBMV did not show ontogenic changes; i.e., it was similar in suckling and adult rats. Also, the levels of SMVT protein and mRNA were similar in the kidneys of both age groups. These data show that biotin uptake by renal and intestinal epithelial cells responds differently to ontogenic regulation. In addition, the ontogenic changes observed in the intestinal biotin uptake process involve the entry step of the vitamin at the BBM and appear to be mediated via a transcriptional mechanism(s).

Presence of multiple sodium-dependent phosphate transport processes in proximal brush-border membrane

1987 ◽  
Vol 252 (2) ◽  
pp. F226-F231 ◽  
Author(s):  
J. J. Walker ◽  
T. S. Yan ◽  
G. A. Quamme
Keyword(s):  
Proximal Tubule ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Phosphate Transport ◽  
Transport Processes ◽  
Proximal Tubules ◽  
High Affinity ◽  
Medullary Tissue ◽  
Sodium Dependent ◽  
Early Proximal Tubule

Renal brush-border membrane phosphate transport was studied in early and late segments of the pig proximal tubule. Vesicles were prepared from early proximal tubules (outer cortical tissue) and late proximal tubules (outer medullary tissue). Sodium-dependent phosphate uptake into brush-border membrane vesicles was determined using voltage clamp at 5-6 s, 21 degrees C. Sodium-dependent D-glucose uptake was determined to verify the cortical and medullary tissue cuts. At pH 8.0 (pHi = pHo), two sodium-dependent phosphate transport systems were evident in the early proximal tubule: a high-affinity system [Km, 0.06 +/- 0.01 mM; maximal transport activity (Vmax), 3.6 +/- 1.1 nmol X mg protein-1 X min-1] and a low-affinity system (Km, 4.11 +/- 0.02 mM; Vmax, 9.7 +/- 0.7 nmol X mg protein-1 X min-1). In the late proximal tubule at pH 8.0, only a single high-affinity transport process (Km, 0.19 +/- 0.7 mM; Vmax, 3.4 +/- 0.5 nmol X mg protein-1 X min-1) was evident. D-Glucose kinetics at pH 7.0 revealed both a high-affinity (Km, 0.55 +/- 0.09 mM) and a low-affinity (Km, 20.09 +/- 1.39 mM) system in the early proximal segment and a single high-affinity (Km, 1.27 +/- 0.36 mM) process in the late segment. These data suggest that two systems, distinct in their affinities and capacities, are involved in both D-glucose and phosphate transport across the brush-border membrane of the early proximal tubule, but that only a single high-affinity system is present in the late segment.

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