Effects of pH on K depolarization and contracture in frog muscles

1979 ◽  
Vol 57 (2) ◽  
pp. 217-219
Author(s):  
Hrvoje Lorković
Keyword(s):  
Rana Temporaria ◽  
Rana Esculenta ◽  
Low Ph ◽  
Fiber Bundles ◽  
Bathing Solution ◽  
Mechanical Tension ◽  
Contraction Coupling ◽  
High K ◽  
Frog Species ◽  
Effects Of Ph

Membrane potential changes and mechanical tension provoked by 20 or 80 mM K at pH 8.0 or 4.5 were measured in muscle fiber bundles from Rana temporaria and Rana esculenta. The bathing solution contained Cl as the main anion. Low pH increased the depolarizing efficiency of high K to about the same degree in muscles of both species of frogs. The tension–[K] relationship was shifted toward lower [K] in muscles from R. temporaria and toward higher [K] in muscles from R. esculenta. It was concluded that the depolarization–contraction coupling was insensitive to pH changes in the former but not in the latter frog species.

scholarly journals Effect of sodium on amiloride- and triamterene-induced current fluctuations in isolated frog skin.

1986 ◽  
Vol 87 (3) ◽  
pp. 425-442 ◽  
Author(s):  
T Hoshiko ◽  
W Van Driessche
Keyword(s):  
Rate Constant ◽  
Frog Skin ◽  
Rana Temporaria ◽  
Rana Esculenta ◽  
Inhibitory Effect ◽  
Corner Frequency ◽  
Bathing Solution ◽  
Association Rate Constant ◽  
Association Rate ◽  
Three State Model

The apparent association constants of two agents, amiloride and triamterene, that block the Na-selective channel of apical membrane of frog skin are shown to decrease as the Na concentration is increased in the apical bathing solution in isolated skin of the frog, Rana temporaria, Rana esculenta, and Rana pipiens. These results were obtained in "normally polarized" skins. These effects were independent of the anion used (chloride or methylsulfate) or the cation used as the Na substitute (Tris, DDA, or K ion). When NaCl was replaced with mannitol, the Na effect on the amiloride association rate constant persisted, which shows that ionic strength was not critically involved. The amiloride corner frequency was unaffected when the clamp potential was altered from +100 to -60 mV. The Na dependence was greatly attenuated or absent when the serosal surface was bathed in 120 mM K Ringer's, an effect that appears to be attributable to some pharmacological effect of high serosal K. A previously described three-state model is used to analyze the inhibitory effect of Na on the blocker association rate constant.

Small woods positively influence the occurrence and abundance of the common frog (Rana temporaria) in a traditional farming landscape

2015 ◽  
Vol 36 (4) ◽  
pp. 417-424 ◽  
Author(s):  
Alexandre Boissinot ◽  
Pierre Grillet ◽  
Aurélien Besnard ◽  
Olivier Lourdais
Keyword(s):  
Western Europe ◽  
Rana Temporaria ◽  
Common Frog ◽  
Traditional Farming ◽  
Critical Determinant ◽  
Southern Margin ◽  
Frog Species ◽  
Frog Rana Temporaria ◽  
The Common ◽  
Extensive Farming

Traditional farming landscape in western Europe is made of a complex mosaic of pastures, cultures, ponds and hedgerows connected with woods. Previous observations in the common frog species suggest that lowland populations are closely associated to wood cover and our aim was to test the validity of this assumption. We studied common frog occurrence and abundance in western central France (Deux-Sèvres department) close to the southern margin of lowland distribution. Our results pointed out that the proportion of woods surface around sampled areas (1 ha) was a critical determinant of common frog presence and abundance. Extensive farming, which maintains a mosaic of small woods, may provide a robust conservation tool for this species.

The effects of pH on force and stiffness development in mouse muscles

1987 ◽  
Vol 65 (8) ◽  
pp. 1798-1801 ◽  
Author(s):  
J. M. Renaud ◽  
R. B. Stein ◽  
T. Gordon
Keyword(s):  
High Frequency ◽  
Small Amplitude ◽  
Force Production ◽  
Muscle Length ◽  
Low Ph ◽  
Muscle Stiffness ◽  
Average Force ◽  
Cross Bridge ◽  
Effects Of Ph ◽  
Cross Bridges

Changes in force and stiffness during contractions of mouse extensor digitorum longus and soleus muscles were measured over a range of extracellular pH from 6.4 to 7.4. Muscle stiffness was measured using small amplitude (<0.1% of muscle length), high frequency (1.5 kHz) oscillations in length. Twitch force was not significantly affected by changes in pH, but the peak force during repetitive stimulation (2, 3, and 20 pulses) was decreased significantly as the pH was reduced. Changes in muscle stiffness with pH were in the same direction, but smaller in extent. If the number of attached cross-bridges in the muscle can be determined from the measurement of small amplitude, high frequency muscle stiffness, then these findings suggest that (a) the number of cross-bridges between thick and thin filaments declines in low pH and (b) the average force per cross-bridge also declines in low pH. The decline in force per cross-bridge could arise from a reduction in the ability of cross-bridges to generate force during their state of active force production and (or) in an increased percentage of bonds in a low force, "rigor" state.

scholarly journals Efficient Heterogeneous Activation of Persulfate by Iron-Modified Biochar for Removal of Antibiotic from Aqueous Solution: A Case Study of Tetracycline Removal

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 49 ◽  
Author(s):  
Van-Truc Nguyen ◽  
Chang-Mao Hung ◽  
Thanh-Binh Nguyen ◽  
Jih-Hsing Chang ◽  
Tsing-Hai Wang ◽  
...  
Keyword(s):  
Organic Contaminants ◽  
Low Ph ◽  
Spent Coffee Grounds ◽  
Modified Biochar ◽  
Batch System ◽  
Coffee Grounds ◽  
Emerging Organic Contaminants ◽  
Effects Of Ph ◽  
Science Community

Waste reutilization is always highly desired in the environmental engineering and science community. In this study, Fe-SCG biochar was functionalized by modifying spent coffee grounds (SCG) with magnetite (Fe3+) at 700 °C and applied for the oxidative removal of tetracycline (TC) with the presence of persulfate (PS). The effects of pH, dosage of biochar and sodium persulfate and initial TC concentration on TC degradation were investigated in a batch system. Our results show that higher TC degradation efficiency was obtained at low pH, low initial TC concentration, and at high dosages of PS and biochar. The highest removal efficiency (96%) was achieved by Fe-SCG/PS under the conditions of pH = 2.0, [Fe-SCG] = 2.5 g/L, [PS] = 60 mM and [TC] = 1 mM. The proposed Fe-SCG catalyst could be a promising effective biochar for the remediation of other emerging organic contaminants.

Interaction between effects of low pH and low ion concentration on mortality during early development of medaka, Oryzias latipes

1989 ◽  
Vol 67 (9) ◽  
pp. 2158-2168 ◽  
Author(s):  
Weerawan Chulakasem ◽  
Jay A. Nelson ◽  
John J. Magnuson
Keyword(s):  
Ionic Strength ◽  
Oryzias Latipes ◽  
Calcium Content ◽  
Explanatory Models ◽  
Low Ph ◽  
Ion Concentration ◽  
Physiological Mechanisms ◽  
Effects Of Ph ◽  
Independent Effects ◽  
Patterns Of Interaction

Eggs and fry of medaka, Oryzias latipes, were incubated continuously from shortly after fertilization until 7 days after hatching using a factorial design with four water conductivities (9, 16, 28, and 49 μS/cm) and four pH levels (4.2, 4.5, 5.6, or 6.6). Results on survival suggest that only during hatching can independent effects of pH and ionic strength be statistically separated. Mortalities of encapsulated embryos and fry were determined by interactions between pH and ionic strength. Sensitivity to dilute, low pH water was greatest in freshly fertilized eggs and 1- to 4-day-old fry. Egg mortality occurred within a day after water hardening, whereas fry mortality occurred more gradually over the 3 days following hatching. Dilute, low pH water did not influence oxygen consumption or calcium content of eggs, yet impeded normal developmental increases in both calcium content and metabolic rate in fry. Results are discussed mechanistically with respect to causes of the mortality, and two explanatory models are proposed. Speculation that patterns of interaction in multivariate analyses can be indicative of physiological mechanisms also is entertained.

The Effects of Low pH and Aluminum on Breeding Success in the Frog Rana temporaria

1992 ◽  
Vol 26 (4) ◽  
pp. 353 ◽  
Author(s):  
Robert C. Beattie ◽  
Richard Tyler-Jones
Keyword(s):  
Breeding Success ◽  
Rana Temporaria ◽  
Low Ph ◽  
Frog Rana Temporaria

Effects of pH on the early development and growth and otolith microstructure of chinook salmon, Oncorhynchus tshawytscha

1985 ◽  
Vol 63 (1) ◽  
pp. 22-27 ◽  
Author(s):  
G. H. Geen ◽  
J. D. Neilson ◽  
M. Bradford
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Growth Increment ◽  
Low Ph ◽  
Acidic Water ◽  
Daily Growth ◽  
Stage Of Development ◽  
Growth Increments ◽  
Effects Of Ph ◽  
Daily Growth Increment

Chinook salmon (Oncorhynchus tshawytscha) eggs, alevins, and fry were reared in pH 4.5, 5.0. 5.5, 6.2 (control), and 7.0 water from the eyed stage of development. Survival through hatching was >90% in all instances. Alevin mortality was high at pH 4.5 and 5.0. Fry were more tolerant of low pH than alevins. Growth rates of alevins and fry held at or above pH 5.0 and 4.5, respectively, were not affected by pH, nor did exposure to acidic water retard otolith development or result in their resorption. One otolith daily growth increment was formed every 24 h in alevins and fry irrespective of pH. Widths of otolith daily growth increments decreased when fry were transferred to pH 4.5 water and increased on their return to higher pH indicating changes in growth rate. Transfer of fry from pH 6.2 to pH 5.0 or 5.5 had no effect on increment widths.

The effect of solution pH and external calcium concentration on the early growth and nodulation of several annual Medicago species

1990 ◽  
Vol 41 (5) ◽  
pp. 933 ◽  
Author(s):  
MA Ewing ◽  
AD Robson
Keyword(s):  
Calcium Concentration ◽  
Acid Soils ◽  
Early Growth ◽  
Low Ph ◽  
Solution Ph ◽  
Nodule Number ◽  
Low Calcium ◽  
Wide Range ◽  
Effects Of Ph ◽  
Annual Medics

The study tested the hypothesis that annual medic species which nodulate well in acid soils in the field (M. murex Willd. and M. polymorpha L.) will nodulate better in acid solutions with low calcium concentrations than annual medics which nodulate poorly in acid soils (M, truncatula Gaertn.). Effects of pH (5.5 and 6.5) and calcium concentration (0.2, 0.5, 1 and 2 mM) on the early growth and nodulation of three annual medic species (M. truncatula, M. polymorpha and M. murex) were investigated. Increasing pH or calcium concentration did not increase plant growth for any of the species. However, nodulation was generally depressed by low pH for all species. Increasing calcium concentration in solution increased nodulation in all species. Effects of low pH and low calcium concentration in decreasing nodule number were much greater for M. truncatula than for M. polymorpha and M. murex. At pH 5.5, M. truncatula failed to nodulate at any calcium concentration, whereas a large proportion of M. murex plants nodulated at 1 mM calcium and some M. polymorpha plants nodulated at 2 mM calcium. At pH 6.5, M. polymorpha required 1 mM calcium in solution for maximum nodule number, and M. murex only 0.5 mM calcium, whereas nodule number for M. truncatula increased up to 2 mM calcium, the highest concentration used. The results provide the basis for a simple screening system to distinguish differences among annual medics in nodulation tolerance to acidity. The maintenance of ranking among species with respect to nodulation over a wide range of stresses induced by combinations of low pH and calcium concentration suggest that screening using a single stress combining these two components would be adequate. Nodulation differences between species can be simply and effectively assessed using a scoring system combining number size and location of nodules.

scholarly journals Binding of active and inactive forms of lipoprotein lipase to heparin. Effects of pH

1985 ◽  
Vol 226 (2) ◽  
pp. 409-413 ◽  
Author(s):  
G Bengtsson-Olivecrona ◽  
T Olivecrona
Keyword(s):  
Catalytic Activity ◽  
Lipoprotein Lipase ◽  
Low Ph ◽  
Cell Surface Receptor ◽  
Physiological Conditions ◽  
Enzyme Binding ◽  
Cell Compartments ◽  
Effects Of Ph ◽  
Surface Receptor ◽  
Active Lipase

Lipoprotein lipase has been shown to bind to, be internalized by, and perhaps be transferred through, a variety of cells. These processes may involve a heparin-like cell-surface receptor and passage through acidified cell compartments. We have therefore studied effects of low pH on the binding of the lipase to heparin and on its catalytic activity. The rate of inactivation of the lipase in solution was found to increase as the pH was lowered. Addition of heparin stabilized the enzyme. Binding of active lipoprotein lipase to heparin-Sepharose could be demonstrated at pH down to 6.5. At pH below 6, binding could not be studied directly because the lipase was too unstable in solution. Lipase bound to heparin-Sepharose could, however, be exposed to pH 4.5 at 10 degrees C with little loss of activity. Binding to heparin-Sepharose also stabilized under physiological conditions (37 degrees C, 0.15 M-NaCl, pH 5.5-7.4). Catalytically inactive lipoprotein lipase retained the ability to bind to heparin-Sepharose. Higher concentrations of salt were needed to displace both active and inactive lipase from heparin-Sepharose at lower pH, indicating that the affinity increased as pH was lowered. The inactive lipase was, however, displaced by lower concentrations of salt than was active lipase.

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