Effect of somatolactin and related hormones on phosphate transport by flounder renal tubule primary cultures

1995 ◽  
Vol 268 (3) ◽  
pp. R577-R582 ◽  
Author(s):  
M. Lu ◽  
P. Swanson ◽  
J. L. Renfro
Keyword(s):  
Primary Cultures ◽  
Phosphate Transport ◽  
Specific Protein ◽  
Dependent Manner ◽  
Initial Exposure ◽  
Ussing Chambers ◽  
Cyclic Monophosphate ◽  
Primary Monolayer ◽  
Dose Dependent ◽  
Primary Monolayer Cultures

Winter flounder renal proximal tubule primary monolayer cultures mounted in Ussing chambers were used to determine the effect of salmon somatolactin (sSL) on transepithelial Pi and Ca2+ transport. sSL stimulated Pi reabsorption in a dose-dependent manner at physiological levels of the hormone (12.5 ng/ml). Net Pi transport was significantly altered by sSL (200 ng/ml) within 2 h after the initial exposure. Ca2+ fluxes were unchanged by the addition of 200 ng/ml sSL. The sSL-induced Pi reabsorption was abolished by 10 microM H-89, a highly specific protein kinase A inhibitor. Moreover the production and release of adenosine 3',5'-cyclic monophosphate were significantly increased after 1 and 2 h of exposure to sSL. The data indicate that sSL directly stimulates net renal Pi reabsorption by an adenosine 3',5'-cyclic monophosphate-dependent pathway. In addition to sSL, flounder SL and rat prolactin greatly, and salmon growth hormone (2.3 micrograms/ml) slightly, increased net Pi reabsorptive flux, whereas salmon prolactin had no effect.

Stanniocalcin stimulates phosphate reabsorption by flounder renal proximal tubule in primary culture

1994 ◽  
Vol 267 (5) ◽  
pp. R1356-R1362 ◽  
Author(s):  
M. Lu ◽  
G. F. Wagner ◽  
J. L. Renfro
Keyword(s):  
Proximal Tubule ◽  
Specific Protein ◽  
Ussing Chambers ◽  
Pi Transport ◽  
Primary Monolayer ◽  
Ovine Prolactin ◽  
Dose Dependent ◽  
Primary Monolayer Cultures ◽  
Dependent Pathway ◽  
Specific Protein Kinase

The effects of several hormones on transepithelial Pi transport were determined in primary monolayer cultures of winter flounder proximal tubule epithelium in Ussing chambers. Salmon stanniocalcin (STC) had a dose-dependent stimulatory effect on net Pi reabsorption within the normal plasma hormone concentration range, 12.5-50 ng/ml (0.25-1.0 nM). Net Pi transport was significantly altered by STC (200 ng/ml) within 30 min and progressively increased from slight net secretion (0.26 +/- 0.744 nmol.cm-2.h-1) in untreated controls to net reabsorption (1.96 +/- 0.729 nmol.cm-2.h-1) after 3 h. The STC effect was mimicked by 10 microM forskolin, whereas 10 microM H-89, a highly specific protein kinase A inhibitor, significantly decreased both STC- and forskolin-induced Pi reabsorption. The release of adenosine 3',5'-cyclic monophosphate (cAMP) was increased more than twofold after a 1-h exposure to STC. This hormone had no effect on transepithelial Ca2+ transport. The results indicate that STC directly stimulates net renal Pi reabsorption by a cAMP-dependent pathway. In addition to STC, bovine parathyroid hormone (100 nM) and ovine prolactin (100 nM) significantly increased net Pi reabsorptive flux.

Effects of pH on phosphate transport by flounder renal tubule primary cultures

1991 ◽  
Vol 260 (4) ◽  
pp. R704-R711 ◽  
Author(s):  
A. Gupta ◽  
J. L. Renfro
Keyword(s):  
Kinase Inhibitor ◽  
Primary Cultures ◽  
Phosphate Transport ◽  
Ussing Chambers ◽  
Fold Reduction ◽  
Effects Of Ph ◽  
Primary Monolayer ◽  
Net Flux ◽  
Luminal Ph ◽  
Stimulation Of

Transepithelial phosphate (Pi) fluxes were determined in primary monolayer cultures of the winter flounder proximal tubule in Ussing chambers. Net Pi secretion, peritubular (P)-to-lumen (L) net flux (Jnet = 17.0 +/- 3.77 nmol.cm-2.h-1), was strongly stimulated by lowering peritubular pH to 6.5 (pHP 6.5 vs. pHL 7.5) compared with control tissues at pH 7.5 (pHP 7.5 vs. pHL 7.5) where net reabsorption (L-to-P Jnet = 1.10 +/- 0.36 nmol.cm-2.h-1) occurred. The stimulation of net secretion by pHP 6.5 was inhibited to 27% of control by 200 microM amiloride. The imposition of a reversed pH gradient (pHL 6.5 vs. pHP 7.5) did not stimulate Pi secretion. Preincubation with 0.5 U/ml phospholipase C caused a nearly fivefold stimulation of Pi secretion compared with the untreated controls. H-7 (100 microM), a protein kinase inhibitor, caused a 2.5-fold reduction in phorbol ester (PE)-induced stimulation of Pi secretion. H-7 also significantly inhibited Pi secretion (50% reduction) when peritubular pH was lowered to 6.5. PE-induced net Pi secretion was significantly lower when luminal pH was lowered to 5.5 compared with controls where luminal pH was kept at 7.5. Amiloride (200 microM) significantly inhibited the PE-induced net Pi secretion in the presence of luminal pH 7.5 but had no significant effect at luminal pH 5.5. Replacement of luminal NaCl with LiCl or isosmolar mannitol significantly reduced net phosphate secretion under the conditions of lowered peritubular pH. Net Pi secretion was also dependent on the maintenance of a cellular Na+ gradient, since 100 microM ouabain inhibited PE-induced net Pi secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Somatostatin inhibition of secretagogue and forskolin-stimulated gastric acid secretion

1988 ◽  
Vol 254 (4) ◽  
pp. G531-G537
Author(s):  
F. Michelangeli ◽  
M. C. Ruiz ◽  
C. L. Rodriguez ◽  
A. Pelacca
Keyword(s):  
Acid Secretion ◽  
Histamine Release ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Direct Stimulation ◽  
Histamine Stimulation ◽  
Ussing Chambers ◽  
Cyclic Monophosphate ◽  
Dose Dependent ◽  
Stimulation Of

The action of somatostatin (SS) on acid secretion and histamine release was studied in isolated gastric mucosa of toads mounted in Ussing chambers. SS inhibited H+ secretion and histamine release stimulated by cholinergic and gastrinergic secretagogues. Exogenous histamine stimulation of H+ secretion was blocked noncompetitively by SS in a dose-dependent manner. In mucosae maximally stimulated by histamine or forskolin and cimetidine, acetylcholine (ACh) and tetragastrin (TG) induced a direct stimulation of the oxyntopeptic cell not inhibited by SS. Indomethacin, an inhibitor of prostaglandin synthesis, did not prevent SS inhibition of histamine stimulation. Pretreatment with SS abolished forskolin stimulation of H+ secretion. SS induced a small inhibition of the stimulatory effect of N6, 2'-O-dibutyryladenosine 3',5'-cyclic monophosphate. These results suggest that SS inhibits acid secretion stimulated by secretagogues through different mechanisms: 1) inhibition of histamine release by ACh and TG, 2) inhibition of endogenous and exogenous histamine stimulation through a blockade of adenylate cyclase, and 3) an inhibitory effect subsequent to the synthesis of adenosine 3',5'-cyclic monophosphate. The direct activation of the oxyntopeptic cell by ACh and TG does not seem to be affected by somatostatin.

scholarly journals VEGF Mediates Retinal Müller Cell Viability and Neuroprotection through BDNF in Diabetes

Biomolecules ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 712
Author(s):  
Yun-Zheng Le ◽  
Bei Xu ◽  
Ana J. Chucair-Elliott ◽  
Huiru Zhang ◽  
Meili Zhu
Keyword(s):  
Specific Protein ◽  
Müller Cell ◽  
Dependent Manner ◽  
Vascular Abnormalities ◽  
Extracellular Signal ◽  
Muller Cell ◽  
Protein Kinase Akt ◽  
Sirna Knockdown ◽  
Endothelial Growth Factor ◽  
Dose Dependent

To investigate the mechanism of vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF) in Müller cell (MC) viability and neuroprotection in diabetic retinopathy (DR), we examined the role of VEGF in MC viability and BDNF production, and the effect of BDNF on MC viability under diabetic conditions. Mouse primary MCs and cells of a rat MC line, rMC1, were used in investigating MC viability and BDNF production under diabetic conditions. VEGF-stimulated BDNF production was confirmed in mice. The mechanism of BDNF-mediated MC viability was examined using siRNA knockdown. Under diabetic conditions, recombinant VEGF (rVEGF) stimulated MC viability and BDNF production in a dose-dependent manner. rBDNF also supported MC viability in a dose-dependent manner. Targeting BDNF receptor tropomyosin receptor kinase B (TRK-B) with siRNA knockdown substantially downregulated the activated (phosphorylated) form of serine/threonine-specific protein kinase (AKT) and extracellular signal-regulated kinase (ERK), classical survival and proliferation mediators. Finally, the loss of MC viability in TrkB siRNA transfected cells under diabetic conditions was rescued by rBDNF. Our results provide direct evidence that VEGF is a positive regulator for BDNF production in diabetes for the first time. This information is essential for developing BDNF-mediated neuroprotection in DR and hypoxic retinal diseases, and for improving anti-VEGF treatment for these blood–retina barrier disorders, in which VEGF is a major therapeutic target for vascular abnormalities.

Effect of aminophylline on the contraction threshold of rat diaphragm fibers

1991 ◽  
Vol 71 (4) ◽  
pp. 1409-1414 ◽  
Author(s):  
A. S. Losavio ◽  
B. A. Kotsias
Keyword(s):  
Membrane Potential ◽  
Sarcoplasmic Reticulum ◽  
Resting Membrane Potential ◽  
Dependent Manner ◽  
Direct Visualization ◽  
Rat Diaphragm ◽  
Current Clamp ◽  
Cyclic Monophosphate ◽  
Dose Dependent

We studied the effect of aminophylline (0.1–1 mM) on the contraction threshold (CT) of rat diaphragm fibers (25 degrees C). The CT was measured by direct visualization (x200) of the fiber under current-clamp conditions. The main findings are the following: 1) Aminophylline lowers the CT, in a dose-dependent manner, toward more negative values of the resting membrane potential (Vm). 2) Dibutyryl adenosine 3′,5′-cyclic monophosphate (2 mM) shifts the CT, although this change is smaller than in the presence of xanthine. 3) Tetracaine (1 mM), a drug that diminishes Ca release from the sarcoplasmic reticulum, reduces the shift induced by 1 mM aminophylline; this is partially overcome by increasing aminophylline concentration to 5 mM. 4) Hyperpolarization of the fibers shifts the CT to more negative Vm. We suggest that the displacement in the CT to more negative Vm plays an important role in the potentiating effect of aminophylline. This could be the result of an enhancement of Ca release from the sarcoplasmic reticulum.

Apical acidification induces paracellular injury in canine gastric mucosal monolayers

1994 ◽  
Vol 267 (6) ◽  
pp. G1012-G1020 ◽  
Author(s):  
M. C. Chen ◽  
A. Chang ◽  
T. Buhl ◽  
M. Tanner ◽  
A. H. Soll
Keyword(s):  
Short Circuit ◽  
Phase 1 ◽  
Short Circuit Current ◽  
Paracellular Permeability ◽  
Ussing Chambers ◽  
Low Concentrations ◽  
Three Phase ◽  
Mucosal Cells ◽  
Primary Monolayer ◽  
Primary Monolayer Cultures

We used primary monolayer cultures of enzyme-dispersed canine oxyntic mucosal cells mounted in Ussing chambers to characterize the apical barrier to H+. [3H]mannitol flux (MF) and [14C]inulin flux (IF) were used as size probes for tight junctions. Apical H+ produced a three-phase effect. In phase 1, as the apical pH was decreased from 7 to about 2.5, resistance (R) increased, but short-circuit current (Isc) did not change. In phase 2, an increased paracellular permeability developed at pH below 2.5-1.7, evidenced by decreased R and increased MF but not IF. Size sieving and monolayer integrity were preserved, and this paracellular leak was either fully reversed or stabilized by apical neutralization, depending on the duration of the paracellular leak. In phase 3, after sustained exposure to an apical pH below approximately 2, transepithelial integrity was lost; R decreased to fluid R, and both MF and IF increased. Basolateral acidification below pH 5.5 produced rapid monolayer disruption. Low concentrations of cytochalasin D (CD) decreased R and increased MF but not IF; apical acidification to pH 4 after CD increased R and decreased the MF, indicating reduced paracellular permeability by apical H+. Apical amiloride did not alter Isc; however, after 48 h of treatment with hydrocortisone and insulin, an amiloride-sensitive Isc component became evident. Our data indicate that the increase in R observed with apical acidification reflects decreased paracellular permeability and that the earliest injury with apical acidification is a selective paracellular leak.

Characterization of the endogenous Na(+)-K(+)-2Cl- cotransporter in Xenopus oocytes

1994 ◽  
Vol 266 (1) ◽  
pp. C284-C292 ◽  
Author(s):  
W. Suvitayavat ◽  
H. C. Palfrey ◽  
M. Haas ◽  
P. B. Dunham ◽  
F. Kalmar ◽  
...  
Keyword(s):  
Xenopus Oocytes ◽  
Dependent Manner ◽  
K Uptake ◽  
Cyclic Monophosphate ◽  
Ehrlich Ascites ◽  
Medium Osmolarity ◽  
Ehrlich Ascites Cell ◽  
Endogenous Activity ◽  
Dose Dependent

Over time, Xenopus laevis changed from producing stage V and VI oocytes with little native Na(+)-K(+)-2Cl- cotransport activity to those with substantial activity. In oocytes with high endogenous activity, K+ uptake, using the tracer 86Rb+ was approximately 20 pmol.min-1.oocyte-1 in the presence of blockers of Na(+)-K(+)-ATPase and conductive K+ transport. Bumetanide (10 microM) inhibited > 90% of this uptake, suggesting involvement of Na(+)-K(+)-2Cl- cotransport. This was confirmed by two observations that are found in this cotransporter in other tissues: 1) The related diuretics, thiobenzmetanide [50% inhibitory concentration (IC50), 2 x 10(-11) M] > bumetanide (IC50, 7 x 10(-8) M) > furosemide (IC50, 2.5 x 10(-6) M) inhibited the cotransporter in a dose-dependent manner. 2) There was little uptake of K+ in the absence of extracellular Na+ or Cl-. Halving medium osmolarity to 92 mosM decreased bumetanide-sensitive K+ uptake by approximately 75%, whereas a doubling of medium osmolarity increased it by approximately 50%. The cotransport activity was increased fourfold by the phosphatase inhibitor calyculin A (200 nM) but was unaffected by 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate, 8-bromoguanosine 3',5'-cyclic monophosphate, ATP, ionomycin, or okadaic acid. Both the photoaffinity bumetanide analogue, 4-[3H]benzoyl-5-sulfamoyl-3-(3-thenyloxy)benzoic acid, and an antiserum raised against Ehrlich ascites cell cotransporter specifically labeled an approximately 140-kDa oocyte membrane protein. These results demonstrated that, in addition to the Na+ pump and K+ channels, K+ uptake in Xenopus oocytes occurs via a loop-diuretic-sensitive Na(+)-K(+)-2Cl- cotransporter.(ABSTRACT TRUNCATED AT 250 WORDS)

Dual pathways regulate neurite outgrowth in enteric ganglia

1994 ◽  
Vol 267 (4) ◽  
pp. G723-G729
Author(s):  
D. M. Simeone ◽  
G. Romanchuk ◽  
M. W. Mulholland
Keyword(s):  
Primary Cultures ◽  
Neuronal Cultures ◽  
Dibutyryl Camp ◽  
Neurite Length ◽  
Alpha Tubulin ◽  
Cyclic Monophosphate ◽  
Enteric Ganglia ◽  
Dependent Protein ◽  
Growth Promoting ◽  
Dose Dependent

Primary cultures of guinea pig myenteric plexus ganglia were used to examine the ability of agents that activate adenylate cyclase or mimic intracellular adenosine 3',5'-cyclic monophosphate (cAMP) to stimulate morphological growth. Dose-dependent increases in neurite length and density were produced in enteric neuronal cultures by forskolin (212% of control), cholera toxin (356% of control), or the permeant cAMP analogues 8-bromoadenosine 3',5'-cyclic monophosphate and dibutyryl cAMP. (R)-p-adenosine 3',5'-cyclic monophosphorothioate, an inhibitor of cAMP-dependent kinases, blocked the growth-promoting effects of cAMP analogues but not of nerve growth factor (NGF). Activation of cAMP-dependent signaling pathways also increased production of mRNA for alpha-tubulin and microtubule-associated protein 2. Dual pathways, regulated by NGF and cAMP-dependent protein kinases, influence growth signaling in enteric ganglia.

scholarly journals Effects of Jiawei Shaoyao-Gancao Decoction and Its Drug-Containing Serum on Proliferation, Apoptosis, and Ultrastructure of Human Adenomyosis Foci Cells

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Yu-yan Zeng ◽  
Kun-yin Li
Keyword(s):  
Electron Microscopy ◽  
Cell Proliferation ◽  
Cell Apoptosis ◽  
Chromatin Condensation ◽  
Primary Cultures ◽  
Cell Ultrastructure ◽  
Dependent Manner ◽  
Transmission Electron ◽  
Dose Dependent ◽  
Insight Into

Objective. The present study aimed to investigate the effects of Jiawei Shaoyao-Gancao Decoction (JSGD) and its drug-containing serum (CDS) on the proliferation, apoptosis, and ultrastructure of human adenomyosis foci cells. Methods. Primary cultures of human adenomyosis foci cells were prepared from hard uterine lesions of adenomyosis patients. The cells were treated with JSGD (10 and 20 mg/ml), CDS, and mifepristone (MIF) for 24 or 48 h. Cell proliferation was detected using CCK-8 assay, cell apoptosis was measured by flow cytometry, and the cell ultrastructure was observed by transmission electron microscopy (TEM). Results. JSGD and CDS significantly induced cell apoptosis and inhibited cell proliferation for 24 h or 48 h, in which the effects of JSGD were in a dose-dependent manner. The effect of CDS for 24 h was higher than that of CDS for 48 h. Moreover, JSGD and CDS treatments induced marked apoptosis in adenomyosis foci cells, characterized by nucleus chromatin, condensation, fragmentation, mitochondria and endoplasmic swelling, and autophagy-lysosome. Conclusions. JSGD and CDS can suppress proliferation and induce apoptosis in adenomyosis foci cells, through altering their ultrastructure. The results provided support for JSGD and CDS in the treatment of adenomyosis and gained further insight into the effect of this prescription.

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