The Electrical Potential Difference Across the Epithelium of Isolated Gills of the Crayfish Austropotamobius Pallipes (Lereboullet)

1965 ◽  
Vol 42 (3) ◽  
pp. 463-474
Author(s):  
P. C. CROGHAN ◽  
R. A. CURRA ◽  
A. P. M. LOCKWOOD
Keyword(s):  
Epithelial Cells ◽  
Cell Membrane ◽  
Body Fluid ◽  
External Medium ◽  
Electrical Potential ◽  
Ringer Solution ◽  
Outer Cell ◽  
Electrical Potential Difference ◽  
Austropotamobius Pallipes ◽  
Outer Cell Membrane

1. A technique is described for recording the electrical potential differences across the epitheium (epithelial potential) of isolated podobranch gills of Austropotamobius pallipes continuously perfused with Ringer solution in various external media. 2. In a medium of 0.01 Ringer, in which the animals had previously been kept, the mean epithelial potential ± standard deviation was -60 ± 12 mV. (Sign defines potential of body fluid with respect to external medium.) Chloride, sodium and potassium must be actively transported into the body fluid against an electrochemical gradient. Calcium and magnesium ions appear to be approximately in equilibrium. 3. The steady-state membrane potentials were recorded in various external concentrations of Ringer solution. The potential is about zero with Ringer solution outside and rises to a maximum with 0.01 Ringer outside. 4. Changes of the electrical potential were recorded when the concentration of a single electrogenic ion was changed in the external medium (0.01 Ringer), and were used to define an apparent transport number of the ion in the outer cell membrane. 5. There was no correlation between the transport numbers and the epithelial potential. 6. There was a continuous gradation of gill types from a predominantly cationpermeable type towards a more chloride permeable type. There is a correlation between the type of gill and the position in the gill series. 7. The properties of the epithelial cells of Austropotamobius gill are significantly different from those of the epithelial cells of frog skin. It is suggested that in Austropotamobius a chloride pump is situated in the outer cell membrane.

scholarly journals β-catenin activation is not involved in sporadic parathyroid carcinomas and adenomas

2010 ◽  
Vol 17 (1) ◽  
pp. 1-6 ◽  
Author(s):  
F Cetani ◽  
E Pardi ◽  
C Banti ◽  
P Collecchi ◽  
P Viacava ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Signaling Pathway ◽  
Direct Sequencing ◽  
Distant Metastases ◽  
Outer Cell ◽  
Tumor Type ◽  
Nuclear Staining ◽  
Cytoplasmic Staining ◽  
Membrane Staining ◽  
Outer Cell Membrane

Aberrant accumulation of β-catenin has been found in various types of human tumors. The aim of this study was to evaluate whether Wnt/β-catenin signaling is activated in parathyroid carcinomas and adenomas. We studied 154 parathyroid tumors (18 carcinomas (13 with distant metastases), six atypical adenomas, and 130 adenomas). Three normal parathyroid tissues were used as control. Direct sequencing of exon 3 of the CTNNB1 gene showed absence of stabilizing mutations in all the tumors. Immunostaining of β-catenin was performed in all carcinomas and in 66 adenomas (including three atypical). Normal parathyroid showed a homogeneous distinct outer cell membrane staining in the majority of cells and no nuclear staining. A weak cytoplasmic staining was observed in one case. All tumors showed negative nuclear staining. With the exception of one carcinoma, which had a negative membrane staining, all other samples showed a membrane staining which was similar to that of the normal parathyroid. β-Catenin expression was heterogeneous with a range of positive cells between 5 and 80%, independently of tumor type. Our results suggest that the Wnt/β-catenin signaling pathway is not involved in the development of parathyroid carcinomas and adenomas.

Release of cyclic AMP by toad urinary bladder

1975 ◽  
Vol 228 (3) ◽  
pp. 954-958 ◽  
Author(s):  
S Urakabe ◽  
JS Handler ◽  
J Orloff
Keyword(s):  
Epithelial Cells ◽  
Urinary Bladder ◽  
Cyclic Amp ◽  
Cell Membrane ◽  
Water Permeability ◽  
Ringer Solution ◽  
Mucosal Surface ◽  
Toad Urinary Bladder ◽  
Solution Bathing

Cyclic AMP accumulates in the Ringer solution bathing the toad urinary bladder in vitro. At least 4 times more cyclic AMP is released into the solution bathing the serosal surface than into the solution bathing the mucosal surface. Most of the cyclic AMP originates in the epithelial cells rather than the stroma. Vasopressin increased the content of cyclic AMP in the epithelial cells and increases the amount of cyclic AMP in the Ringer solution. Since there is not an increase in medium cyclic AMP when cell cyclic AMP levels are increased by theophylline, it is suggested that theophylline may reduce the permeability of the cell membrane to cyclic AMP. Finally, it is demonstrated that 10 mM NaF increase the amount of cyclic AMP in the epithelial cells and in the solution bathing the bladder, but block the effect of vasopressin on water permeability, presumably at a step subsequent to the formation of cyclic AMP.

Cl- secretion by cultured shark rectal gland cells. II. Effects of forskolin on cellular electrophysiology

1991 ◽  
Vol 260 (4) ◽  
pp. C824-C831 ◽  
Author(s):  
W. M. Moran ◽  
J. D. Valentich
Keyword(s):  
Apical Membrane ◽  
Basolateral Membrane ◽  
Electrical Potential ◽  
Ringer Solution ◽  
Rectal Gland ◽  
Electrical Potential Difference ◽  
Electrophysiological Properties ◽  
Shark Rectal Gland ◽  
Membrane Electrical Potential ◽  
Cl Conductance

Employing microelectrode techniques we have assessed the cellular electrophysiological properties of shark rectal gland (SRG) cells in primary culture. In the absence of secretagogues a 10-fold reduction in the Cl- concentration of the apical superfusate shark Ringer solution had little effect on either apical membrane electrical potential difference (Va) or fractional resistance (fRa), indicating little, if any, apical membrane Cl- conductance. Superfusing the basolateral surface with high-K+ shark Ringer solution (K+ increased 10-fold) depolarized the basolateral membrane electrical potential difference (Vb) by 43 mV, indicating that this barrier is largely K+ conductive. In addition, basolateral Ba2+ (5 mM) depolarized Vb by 12 mV and reduced fRa from 0.92 to 0.58, results consistent with a K(+)-conductive basolateral membrane in unstimulated SRG cells. Basolateral forskolin (10(-6) M) depolarized Va by 25 mV and caused a dramatic reduction in fRa from 0.97 to approximately 0.10. Under these conditions, a 10-fold decrease in apical superfusate Cl- concentration depolarized Va by 37 mV, revealing an adenosine 3',5'-cyclic monophosphate-induced apical membrane Cl- conductance. The time course of the forskolin-induced changes in Va and Vb suggests that the basolateral membrane K+ conductance increased and maintained the driving force for apical Cl- exit, as in other Cl(-)-secreting epithelia. These electrophysiological properties compare favorably with those of the perfused SRG tubule and indicate that SRG primary cultures are a suitable model for Cl(-)-secreting epithelia.

scholarly journals Damage of lipopolysaccharides in outer cell membrane and production of ROS-mediated stress within bacteria makes nano zinc oxide a bactericidal agent

2014 ◽  
Vol 5 (7) ◽  
pp. 857-866 ◽  
Author(s):  
Prasun Patra ◽  
Shuvrodeb Roy ◽  
Sampad Sarkar ◽  
Shouvik Mitra ◽  
Saheli Pradhan ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Cell Membrane ◽  
Outer Cell ◽  
Nano Zinc Oxide ◽  
Outer Cell Membrane ◽  
Nano Zinc ◽  
Bactericidal Agent

Sodium transport and the cellular sodium transport pool of colonic epithelium: effects of sodium loading, aldosterone and lithium

1987 ◽  
Vol 112 (2) ◽  
pp. 247-252 ◽  
Author(s):  
C. J. Edmonds ◽  
J. Mackenzie
Keyword(s):  
Epithelial Cells ◽  
Sodium Transport ◽  
Time Course ◽  
Electrical Potential ◽  
Electrical Potential Difference ◽  
Active Sodium ◽  
Prolonged Infusion ◽  
Sodium Loading ◽  
Sodium Flux

ABSTRACT The cellular sodium transport pool and sodium transepithelial fluxes were investigated in vivo in rat distal colon in relation to sodium loading by intravenous infusion (3·5 h), and to short (4 h) and prolonged (72 h) i.v. administration of aldosterone. Considerable natriuresis and increase in body sodium content were produced by the sodium load but there was no significant effect on the transcellular sodium flux (active absorption from lumen to plasma) or on the sodium transport pool. Both short and prolonged aldosteronism produced similar increases in the transport pool and in the transcellular sodium flux, but the transepithelial electrical potential difference (p.d.) was significantly greater in rats given the prolonged infusion. Addition of amiloride to the solution in the lumen of the colon almost completely abolished the p.d., the transport pool and the transcellular sodium flux of the rats receiving prolonged infusion, but had much less effect in those given the short infusion. The time-course of recovery of p.d. following prolonged aldosteronism was similar to that described for the turnover rate of rat colonic epithelial cells. Lithium within the lumen had no significant effect in untreated rats but after prolonged aldosterone infusion lithium reduced the p.d. and the transcellular sodium flux although the transport pool was not reduced. These findings are consistent with the hypothesis that aldosteronism renders the apical membranes of the epithelial cells permeable to lithium and that intracellular accumulation of lithium depresses active sodium transfer. The observations are interpreted in terms of an epithelial model in which aldosterone induces amiloride-sensitive pathways (diffusion channels permeable to sodium and lithium) in the apical membrane which totally replace the amiloride-insensitive pathways when aldosteronism is prolonged; the resulting expansion of the sodium transport pool is the stimulus for increased active sodium transport across the basolateral membranes. J. Endocr. (1987) 112, 247–252

scholarly journals THE EFFECTS OF MAGNESIUM ON NUCLEOSIDE PHOSPHATASE ACTIVITY IN FROG SKIN

1967 ◽  
Vol 33 (2) ◽  
pp. 411-418 ◽  
Author(s):  
Rolf H. Dahl ◽  
James N. Pratley
Keyword(s):  
Cell Membrane ◽  
Frog Skin ◽  
Short Circuit ◽  
Electrical Potential ◽  
Short Circuit Current ◽  
Spectrophotometric Analysis ◽  
Electrical Potential Difference ◽  
Ion Pump ◽  
Pump System ◽  
Nucleoside Triphosphatase

Histochemical tests, employing the Wachstein-Meisel medium, indicate that nucleoside triphosphatase activity is found predominantly in two areas of the frog skin epidermis: (1) in mitochondria, where activity is enhanced by dinitrophenol, Mg2+ dependent, but inhibited by fixation; and (2) apparently associated with cell membranes of the middle and outer portions of the epidermis, where activity is inhibited by Mg2+, unaffected by dinitrophenol, and only slightly reduced by fixation. Spectrophotometric analysis shows that Mg2+ in the medium does not increase spontaneous hydrolysis of ATP, thus obviating the possible explanation that changes in substrate concentrations in the medium lead to alterations in the "staining" distributions. It is postulated that perhaps the two enzymes differ in their requirements for substrate—one requiring the polyphosphate to be in complexed form with Mg2+, the other uncomplexed. Concentrations of Mg2+ required to inhibit cell membrane nucleoside triphosphatase activity also inhibit the electrical potential difference and short-circuit current of the frog skin. Although these observations might be taken as presumptive evidence of the cell membrane enzyme as a component of the ion pump system, because of certain dissimilarities with respect to the biochemists' "transport ATPase" and for other reasons discussed in the paper, any definite conclusions in this regard are premature.

The feeding site and probable feeding mechanism of the parasitic nematode Capillaria hepatica (Bancroft, 1893)

1974 ◽  
Vol 52 (10) ◽  
pp. 1215-1220 ◽  
Author(s):  
K. A. Wright
Keyword(s):  
Cell Membrane ◽  
Light And Electron Microscopy ◽  
Circulatory System ◽  
Outer Cell ◽  
Feeding Site ◽  
Capillaria Hepatica ◽  
Parenchymal Liver ◽  
Outer Cell Membrane ◽  
Tissue Fluids ◽  
Nucleolar Components

Examination by light and electron microscopy of the tissue surrounding the anterior end of the trichuroid nematode Capillaria hepatica in the liver of its mouse host indicates that the nematode is enclosed by multinucleate cytoplasmic masses originating from parenchymal liver cells. These cytoplasmic masses have desmosomal contacts with adjacent cells. Nuclei often have an irregularly expanded nuclear envelope, greatly increased amounts of heterochromatin or increases in interchromatinic and perichromatinic granules, and segregated nucleolar components. Mitochondria are swollen and endoplasmic reticulum is swollen or vesiculated to varying degrees. The outer cell membrane of the cytoplasmic masses is thrown into extensive irregular folds, but on the surface next to the nematode, no cell membrane can be found. As the nematode's intestinal contents include remnants of cellular materials, it seems likely that the nematode feeds upon the cytoplasm surrounding its anterior region. Unsuccessful attempts to demonstrate the uptake of trypan blue, colloidal gold, or ferritin injected into the host's circulatory system further suggest that this nematode feeds from the induced host reaction rather than from blood or tissue fluids.

Extra- and intracellular metabolism of platelet-activating factor by cultured mesangial cells

1989 ◽  
Vol 256 (4) ◽  
pp. F735-F741
Author(s):  
R. Neuwirth ◽  
N. Ardaillou ◽  
D. Schlondorff
Keyword(s):  
Cell Membrane ◽  
Cell Surface ◽  
Phospholipase A2 ◽  
Mesangial Cells ◽  
Platelet Activating Factor ◽  
Outer Cell ◽  
Human Mesangial Cells ◽  
Rapid Inactivation ◽  
Outer Cell Membrane ◽  
Intracellular Metabolism

Metabolism of platelet-activating factor (PAF) was examined in cultured mesangial cells from human and rat glomeruli. Human mesangial cells, similar to those from rat, generated PAF after A23187. Both human and rat mesangial cells rapidly hydrolyzed [3H]PAF to lyso-[3H]PAF, and reacylated it into 1-alkyl-2-acyl glycerophosphocholine. Extra- and intracellular metabolism of PAF was then analyzed separately. The majority of [3H]PAF metabolism occurred extracellularly and generated Lyso-[3H]PAF. Intracellularly generated lyso-PAF was rapidly converted to 1-alkyl-2-acyl glycerophosphocholine. Cells prelabeled with [3H]PAF released some [3H]PAF within minutes and then rapidly converted it to lyso-PAF extracellularly. Under control conditions no acetylhydrolase activity was released from cells into the buffer. Acetylhydrolase activity could, however, be released from cell surface into buffer by limited trypsinization, supporting its location on the outer cell membrane. The acetylhydrolase activity was different from phospholipase A2, since phosphatidylcholine was not a substrate for the enzyme. In summary our results show that both rat and human mesangial cells can generate and metabolize PAF. Acetylhydrolase for PAF is present intracellularly, but also and predominantly on the outer cell surface of cells. This ectoenzymatic acetylhydrolase activity may be important in the rapid inactivation of PAF presented to cells, thus protecting cells from deleterious effects of PAF.

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