Potassium exchange in the whole cell, cytoplasm, and nucleus of amphibian oocytes

1980 ◽  
Vol 238 (3) ◽  
pp. C133-C138 ◽  
Author(s):  
M. Frank ◽  
S. B. Horowitz
Keyword(s):  
Isotope Exchange ◽  
Small Decrease ◽  
Solute Redistribution ◽  
Cell Cytoplasm ◽  
First Order ◽  
High K ◽  
Oocyte Cytoplasm ◽  
K Concentration ◽  
Potassium Exchange ◽  
K Activity

Potassium isotope exchange was studied in whole oocytes, with and without ovarian follicles, and in oocyte cytoplasm and nucleus. Cryomicrodissection was used to prevent solute redistribution during nuclear and cytoplasmic separation. Manual follicle removal causes a small decrease in the K+ of the preparation. No effect of follicle removal is seen on 42K+ exchange. Whole oocyte exchange is multiphasic and reflects the presence of two intracellular K+ fractions. One of these fractions is present in both nucleus and cytoplasm. It exhibits first-order exponential kinetics, apparently established at the cell membrane. The second fraction is restricted to cytoplasm and exchanges at an imperceptible rate. The fractions differ in pre- and posthibernation oocytes. These observations clarify the mechanism whereby nuclear/cytoplasmic K+ concentration asymmetries are maintained and the mechanisms responsible for the high K+-activity coefficient previously reported in these cells.

scholarly journals The Effect of High K+ Concentration in Perilymph upon the First Order Neuron of the Guinea Pig

1986 ◽  
Vol 1986 (Supplement8) ◽  
pp. 73-79
Author(s):  
Tetsuaki Kawase ◽  
Jun Kusakari ◽  
Tomonori Takasaka
Keyword(s):  
Guinea Pig ◽  
First Order ◽  
High K ◽  
Order Neuron ◽  
K Concentration

Hair cell changes after cationic stimulation of corti's organ

1989 ◽  
Vol 47 ◽  
pp. 798-799
Author(s):  
Cesar D. Fermin ◽  
Hans-Peter Zenner
Keyword(s):  
Organ Of Corti ◽  
Cross Sectional ◽  
Surface Areas ◽  
High K ◽  
Anatomical Arrangement ◽  
Cell Cytosol ◽  
High Concentrations ◽  
K Concentration ◽  
Cell Changes

Contraction of outer and inner hair cells (OHC&IHC) in the Organ of Corti (OC) of the inner ear is necessary for sound transduction. Getting at HC in vivo preparations is difficult. Thus, isolated HCs have been used to study OHC properties. Even though viability has been shown in isolated (iOHC) preparations by good responses to current and cationic stimulation, the contribution of adjoining cells can not be explained with iOHC preparations. This study was undertaken to examine changes in the OHC after expossure of the OHC to high concentrations of potassium (K) and sodium (Na), by carefully immersing the OC in either artifical endolymph or perilymph. After K and Na exposure, OCs were fixed with 3% glutaraldehyde, post-fixed in osmium, separated into base, middle and apex and embedded in Araldite™. One μm thick sections were prepared for analysis with the light and E.M. Cross sectional areas were measured with Bioquant™ software.Potassium and sodium both cause isolated guinea pig OHC to contract. In vivo high K concentration may cause uncontrolled and sustained contractions that could contribute to Meniere's disease. The behavior of OHC in the vivo setting might be very different from that of iOHC. We show here changes of the cell cytosol and cisterns caused by K and Na to OHC in situs. The table below shows results from cross sectional area measurements of OHC from OC that were exposed to either K or Na. As one would expect, from the anatomical arrangement of the OC, OHC#l that are supported by rigid tissue would probably be displaced (move) less than those OHC located away from the pillar. Surprisingly, cells in the middle turn of the cochlea changed their surface areas more than those at either end of the cochlea. Moreover, changes in surface area do not seem to differ between K and Na treated OCs.

scholarly journals Further Observations on the Regulation of KCl ABSORPTION ACROSS LOCUST RECTUM

1985 ◽  
Vol 116 (1) ◽  
pp. 153-167
Author(s):  
J. W. HANRAHAN ◽  
J. E. PHILLIPS
Keyword(s):  
Chloride Transport ◽  
Short Circuit ◽  
Membrane Conductance ◽  
Short Circuit Current ◽  
Membrane Resistance ◽  
Open Circuit ◽  
High K ◽  
K Concentration ◽  
K Permeability

1. Electrophysiological and tracer flux techniques were used to studyregulation of KC1 reabsorption across locust recta. Physiologically high K+levels (100 mmolI−1) on the lumen side stimulated net 36Cl flux and reduced the theoretical energy cost of anion transport under open-circuit conductions. 2. The stimulation of short-circuit current (Ibc i.e. active C− absorption) by crude corpora cardiaca extracts (CC) was not dependent on exogenous Ca2+. Stimulations of Ibc were greatly enhanced in the presence of theophylline, indicating that the rate of synthesis of cAMP is increased by CC extracts. High CC levels lowered transepithelial resistance (Rt), suggesting that chloride transport stimulating hormone (CTSH) regulates both active Cl− absorption and counter-ion (K+) permeability. 3. High mucosal osmolarity or K+ concentration decreased Ibc and caused a disproportionately large increase in Rt, consistent with a decrease in theshunt (K+) conductance. Measurements of relative mucosal-to-serosal membrane resistance confirmed that high mucosal K+ levels reduced apical membrane conductance. Lowering mucosal pH to values observed in vivo atthe end of resorptive cycles also inhibited Ibc, apparently without affecting K+ permeability.

Evidence for calcium inactivation during hormone release in the rat neurohypophysis

1976 ◽  
Vol 65 (3) ◽  
pp. 669-683
Author(s):  
J. J. Nordmann
Keyword(s):  
Hormone Secretion ◽  
Calcium Ionophore ◽  
High Rate ◽  
Hormone Release ◽  
45Ca Uptake ◽  
High K ◽  
K Concentration ◽  
The Relationship ◽  
Internal Calcium

1. A study has been made of the relationship between 45Ca uptake into and hormone release from isolated rat neurohypophyses incubated in vitro. 2. Hormone secretion is triggered by high-K (56 mM) but long exposure to the stimulus does not generate a maintained release of hormone. 3. When hormone release began to wane, addition of Ba of La increased hormone output which suggests that the decline in output did not result from depletion of the neurosecretory granules at the nerve terminals. 4. 45Ca uptake is enhanced in the presence of high-K concentration, but the initial high rate declines during long exposure to the potassium stimulus with a time constant similar to that of the decline in hormone release. 5. After a period of incubation in a K-rich, calcium-free medium, addition of calcium to the medium induced hormone release. The magnitude of this release was dependent on the time of exposure to excess potassium. 6. After inactivation of secretion, mobilization of internal calcium by means of a calcium ionophore increased hormone release.

scholarly journals THE EFFECT OF ENVIRONMENTAL POTASSIUM AND CALCIUM CONCENTRATIONS ON THE RECOVERY OF THE ACTION POTENTIAL AND RELATED FUNCTIONS OF NERVE

1947 ◽  
Vol 30 (6) ◽  
pp. 493-517 ◽  
Author(s):  
Helen Tredway Graham ◽  
H. A. Blair
Keyword(s):  
Critical Level ◽  
Specific Effect ◽  
The Other ◽  
Level Control ◽  
Definite Effect ◽  
High K ◽  
Low Levels ◽  
K Concentration ◽  
Low K ◽  
Frog Sciatic Nerve

1. When the Ringer's solution applied to isolated frog sciatic nerve contains K+ in concentrations greater than 2 x standard, the height of the spike and of the after-potential is decreased, as is the duration of the after-potential; recovery of height and of excitability following response is delayed; degree and duration of supernormal excitability are decreased; postcathodal depression and postanodal enhancement are increased and prolonged. 2. The nerve functions just listed in general all change in the opposite direction when exposed' to increased environmental [Ca++]. (4.5–20 x standard) or decreased [K+] (0.05–0.2 x standard). The effects of decreased [Ca++] (0.20–0.25 x standard) are indeterminate. 3. When [K+] and [Ca++] are both greater than 2 x standard, whatever the ratio between the concentrations the effects characteristic of high [K+] eventually predominate. However, these effects, except for those involving spike height, are preceded by effects characteristic of high [Ca++] when this cation is present in sufficient excess. 4. When [K+] and [Ca++] are reduced to equal low levels (0.1–0.2 x standard), effects characteristic of low [K+] and high [Ca++] are obtained. 5. The experimentally determined order of ability of the environments to produce changes characteristic of high K+ (which is the reverse of the order of their ability to produce changes characteristic of high [Ca++]), is not the order of their K+ or Ca++ concentrations, nor of the ratio between these concentrations (Table II). 6. The results may be explained by the assumption that the functions investigated are all to greater or less degree controlled by (1) the [K+]/[Ca++] ratio and (2) the K+ concentration, at least when this exceeds a critical level. Control by [K+] is more effective for spike height and its recovery after stimulation than for the other functions. The special rôle of K+ is attributed to an unknown specific effect of this ion which Ca++ is unable to oppose. It is suggested that this K+ effect in general becomes marked on the frog nerve functions investigated when the K+ concentration is somewhat above 2 x standard, while the [K+]/[Ca++] ratio must be changed by a factor of 4 or more before it exerts a definite effect on these functions. 7. In standard and in modified cationic environments, nerve functions vary in the ease with which they manifest changes characteristic of high [K+] or of high [Ca++]. 8. The after-potential functions are less completely controlled by the cationic environment than are the other functions investigated.

scholarly journals Lowering of the extracellular Na+ concentration enhances high-K+-induced formation of inositol phosphates in the guinea-pig ileum

1988 ◽  
Vol 252 (3) ◽  
pp. 883-888 ◽  
Author(s):  
T Sasaguri ◽  
S P Watson
Keyword(s):  
Guinea Pig ◽  
Inositol Phosphates ◽  
Induced Response ◽  
Guinea Pig Ileum ◽  
Tissue Slices ◽  
Phospholipid Hydrolysis ◽  
Collagenase Treatment ◽  
High K ◽  
K Concentration ◽  
Dispersed Cells

1. Formation of inositol phosphates (InsPs) was measured in cross-chopped slices or dispersed cells, isolated by collagenase treatment, of guinea-pig ileum longitudinal smooth muscle pre-labelled with [3H]inositol. 2. Elevation of the extracellular K+ concentration by equimolar replacement of Na+ induced accumulation of InsPs in the dispersed cells and in the tissue slices. These effects were blocked by neither tetrodotoxin (1 microM) nor atropine (10 microM), and were approximately additive with carbachol-induced accumulation. 3. In the tissue slices, the response to K+ was partially inhibited by nifedipine (10 microM) and by CdCl2 (0.3 mM), but the carbachol-induced response was not altered. 4. Accumulation of InsPs induced by KCl-excess solution (high-K+ solution without Na+ replacement) was suppressed strongly by nifedipine and completely by CdCl2. The response to KCl excess was approx. 40% of that to high K+ with Na+ replacement. 5. Low-NaCl solution (replacement of NaCl with equimolar sucrose) also produced InsPs, and this was not blocked by either nifedipine (10 microM) or CdCl2 (0.3 mM). 6. The formation of InsPs by a maximally effective concentration of carbachol (1 mM) in the presence of KCl excess or low NaCl was greater than the additive effect of the two stimuli on their own. Enhancement of the carbachol-induced response by KCl excess disappeared in the presence of CdCl2 (0.3 mM). 7. These data suggest that formation of InsPs induced by high-K+ solution with equimolar replacement of Na+ consists of two components, i.e. high-K+-induced inositol-phospholipid hydrolysis by Ca2+ entry through voltage-sensitive channels, and low-Na+-induced formation of InsPs, insensitive to Ca2+ antagonists, but that both of them do not contribute significantly to the activation of phospholipase C by muscarinic stimuli.

scholarly journals Stepwise Priming by Acidic pH and a High K+ Concentration Is Required for Efficient Uncoating of Influenza A Virus Cores after Penetration

2014 ◽  
Vol 88 (22) ◽  
pp. 13029-13046 ◽  
Author(s):  
S. Stauffer ◽  
Y. Feng ◽  
F. Nebioglu ◽  
R. Heilig ◽  
P. Picotti ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Influenza A ◽  
Acidic Ph ◽  
High K ◽  
K Concentration

scholarly journals Effects of High Potassium and Low Temperature on the Growth and Magnesium Nutrition of Different Tomato Cultivars

HortScience ◽  
2018 ◽  
Vol 53 (5) ◽  
pp. 710-714 ◽  
Author(s):  
Huixia Li ◽  
Zhujun Chen ◽  
Ting Zhou ◽  
Yan Liu ◽  
Sajjad Raza ◽  
...  
Keyword(s):  
Low Temperature ◽  
Shoot Biomass ◽  
Total Biomass ◽  
High Potassium ◽  
Hydroponic Experiment ◽  
Root Shoot Ratio ◽  
High K ◽  
Significant Difference ◽  
Tomato Cultivars ◽  
K Concentration

The interaction between potassium (K) and magnesium (Mg) in plants has been intensively studied. However, the responses of different tomato (Solanum lycopersicum L.) cultivars to high K levels at low temperatures remained unclear. Herein, a complete randomized hydroponic experiment was conducted to evaluate the effects of temperature (25 °C day/18 °C night vs. 15 °C day/8 °C night) and K concentrations (156 mg·L−1 vs. 468 mg·L−1) on the growth and Mg nutrition of tomato cultivars Gailiangmaofen (MF) and Jinpeng No. 1 (JP). Compared with the control temperature (25 °C day/18 °C night), the low temperature decreased total biomass, shoot biomass, and Mg uptake in shoot by 17.3%, 24.1%, and 11.8%, respectively; however, the root/shoot ratio was increased. High K had no significant effect on plant growth or biomass compared with the control K concentration (156 mg·L−1); however, Mg concentrations and uptake in shoot were significantly lower under high-K treatment. Significant difference was observed for K uptake, but not for Mg uptake, between the two cultivars. There was no significant interaction between temperature and high K on Mg uptake of tomato, so a combined stress of low temperature and high K further inhibited Mg uptake and transport. Low temperature and high K increased the risk of Mg deficiency in tomato.

scholarly journals Fluid Infiltration and Mass Transfer along a Lamprophyre Dyke–Marble Contact: An Example from the South-Western Korean Peninsula

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 828
Author(s):  
Jungrae Noh ◽  
Changyeob Kim ◽  
Vinod O. Samuel ◽  
Yirang Jang ◽  
Seung-Ik Park ◽  
...  
Keyword(s):  
Contact Zone ◽  
Fluid Phase ◽  
Major And Trace Elements ◽  
Dolomitic Marble ◽  
Fluid Infiltration ◽  
High K ◽  
Geochemical Variations ◽  
Gyeonggi Massif ◽  
Fluid Phase Equilibria ◽  
K Activity

In this contribution, we report the metasomatic characteristics of a lamprophyre dyke–marble contact zone from the Hongseong–Imjingang belt along the western Gyeonggi Massif, South Korea. The lamprophyre dyke intruded into the dolomitic marble, forming a serpentinized contact zone. The zone consists of olivine, serpentine, calcite, dolomite, biotite, spinel, and hematite. Minor F and Cl contents in the serpentine and biotite indicate the composition of the infiltrating H2O-CO2 fluid. SiO2 (12.42 wt %), FeO (1.83 wt %), K2O (0.03 wt %), Sr (89 ppm), U (0.7 ppm), Th (1.44 ppm), and rare earth elements (REEs) are highly mobile, while Zr, Cr, and Ba are moderately mobile in the fluid. Phase equilibria modelling suggests that the olivine, spinel, biotite, and calcite assemblage might be formed by the dissolution of dolomite at ~700 °C, 130 MPa. Such modelling requires stable diopside in the observed conditions in the presence of silica-saturated fluid. The lack of diopside in the metasomatized region is due to the high K activity of the fluid. Our log activity K2O (aK2O)–temperature pseudosection shows that at aK2O~−40, the olivine, spinel, biotite, and calcite assemblage is stable without diopside. Subsequently, at ~450 °C, 130 MPa, serpentine is formed due to the infiltration of H2O during the cooling of the lamprophyre dyke. This suggests that hot H2O-CO2 fluids with dissolved major and trace elements infiltrated through fractures, grain boundaries, and micron-scale porosity, which dissolved dolomite in the marble and precipitated the observed olivine-bearing peak metasomatic assemblage. During cooling, exsolved CO2 could increase the water activity to stabilize the serpentine. Our example implies that dissolution-reprecipitation is an important process, locally and regionally, that could impart important textural and geochemical variations in metasomatized rocks.

Adenosine potentiates flow-induced dilation of coronary arterioles by activating KATP channels in endothelium

1995 ◽  
Vol 269 (2) ◽  
pp. H541-H549 ◽  
Author(s):  
L. Kuo ◽  
J. D. Chancellor
Keyword(s):  
Katp Channels ◽  
Intraluminal Pressure ◽  
Maximum Diameter ◽  
Induced Response ◽  
Endothelial Denudation ◽  
High K ◽  
Order Of Magnitude ◽  
K Concentration ◽  
The Right ◽  
Coronary Arterioles

Coronary microvascular diameter is significantly influenced by adenosine and flow. However, the interaction between these two regulatory mechanisms in the control of coronary microvascular tone remains unknown. Because adenosine can activate ATP-sensitive K+ (KATP) channels and these channels are located on the endothelium in addition to vascular smooth muscle, we hypothesized that adenosine can potentiate flow-induced vasodilation by activating endothelial KATP channels in the coronary microcirculation. To test this hypothesis, experiments were performed in porcine subepicardial coronary arterioles (50-150 microns) using isolated, cannulated vessel techniques to allow intraluminal pressure and flow to be independently controlled. All vessels developed active tone, approximately 67-73% of maximum diameter, at 60 cmH2O intraluminal pressure and showed graded dilation to stepwise increases in flow. The magnitude of flow-induced dilation was potentiated by a threshold dose of adenosine (10(-10) M) but not by nitroprusside (10(-10) M). Luminal application of a high K+ concentration ([K+]) (40 mM) completely blocked flow-induced arteriolar dilation. In addition, luminal glibenclamide (10(-6) M) abolished the adenosine-potentiated component of flow-induced response. Indomethacin (10(-5) M) did not alter the dose-dependent dilation to adenosine. However, endothelial denudation, NG-monomethyl-L-arginine (10(-5) M), and luminal administration of a high [K+] or glibenclamide each produced identical inhibition of adenosine-induced vasodilation by shifting the 50% effective dose to the right by an order of magnitude. In contrast, vasodilation in response to nitroprusside was not altered by these pharmacological interventions.(ABSTRACT TRUNCATED AT 250 WORDS)

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