Effects of step changes in pH on isometric tetanic tension of toad sartorius muscle

1983 ◽  
Vol 61 (8) ◽  
pp. 830-835 ◽  
Author(s):  
J. M. Renaud ◽  
E. Don Stevens
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Rapid Change ◽  
Carbon Dioxide Concentration ◽  
Physiological Solution ◽  
Acclimation Temperature ◽  
Sartorius Muscle ◽  
Bathing Solution ◽  
Ph Change ◽  
Tetanic Tension

The effect of a rapid change in pHe (pH of bathing solution) on the isometric tetanic tension developed by sartorius muscles of toads acclimated to 5 and 25 °C was measured at 5 and 25 °C. The pH was altered by changing the carbon dioxide concentration of a bicarbonate buffered physiological solution. Acclimation temperature did not modify the response to a rapid change in pH, but test temperature did. Following a pH decrease from 9.0 to 6.0, tetanic tension decreased at a faster rate at 5 °C than at 25 °C. A new steady state was reached in 15 min at 5 °C but in 40 min at 25 °C. Following a pH increase from 6.0 to 8.5, tetanic tension increased at a faster rate at 25 °C than at 5 °C. A new steady state was reached in 60 min at 5 °C but in 10 min at 25 °C. We conclude that the rate of carbon dioxide diffusion through the sartorius muscle is only one factor that determines how rapidly tetanic tension changes following the step change in pH, and that muscle resists pH change more effectively at higher temperatures.

scholarly journals USE OF A GLASS ELECTRODE FOR MEASURING RAPID CHANGES IN PHOTOSYNTHETIC RATES

1954 ◽  
Vol 37 (6) ◽  
pp. 753-774 ◽  
Author(s):  
Jerome L. Rosenberg
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Photosynthetic Rate ◽  
Carbon Dioxide Concentration ◽  
Glass Electrode ◽  
High Light ◽  
Gas Streams ◽  
Partial Pressures ◽  
Rapid Changes ◽  
Concentration Changes

1. A continuously recording glass electrode apparatus has been described for measuring carbon dioxide concentration changes in solution. The limits of applicability of the apparatus have been analyzed. 2. The glass electrode apparatus has been used for the measurement of transient rates of photosynthesis by algal suspensions. 3. The decline of the photosynthetic rate in high light at carbon dioxide partial pressures less than 0.5 per cent atmosphere, observed in the glass electrode apparatus, has been confirmed by steady state experiments in which flowing gas streams were analyzed.

scholarly journals Modeling the Non–Steady State Respiratory Effects of Remifentanil in Awake and Propofol-sedated Healthy Volunteers

2010 ◽  
Vol 112 (6) ◽  
pp. 1382-1395 ◽  
Author(s):  
Erik Olofsen ◽  
Merel Boom ◽  
Diederik Nieuwenhuijs ◽  
Elise Sarton ◽  
Luc Teppema ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Steady State ◽  
Partial Pressure ◽  
Healthy Volunteers ◽  
Respiratory Depression ◽  
Low Dose ◽  
Carbon Dioxide Concentration ◽  
Model Parameters ◽  
State Models ◽  
End Tidal

Background Few studies address the dynamic effect of opioids on respiration. Models with intact feedback control of carbon dioxide on ventilation (non-steady-state models) that correctly incorporate the complex interaction among drug concentration, end-tidal partial pressure of carbon dioxide concentration, and ventilation yield reliable descriptions and predictions of the behavior of opioids. The authors measured the effect of remifentanil on respiration and developed a model of remifentanil-induced respiratory depression. Methods Ten male healthy volunteers received remifentanil infusions with different infusion speeds (target concentrations: 4-9 ng/ml; at infusion rates: 0.17-9 ng x ml x min) while awake and at the background of low-dose propofol. The data were analyzed with a nonlinear model consisting of two additive linear parts, one describing the depressant effect of remifentanil and the other describing the stimulatory effect of carbon dioxide on ventilation. Results The model adequately described the data including the occurrence of apnea. Most important model parameters were as follows: C50 for respiratory depression 1.6 +/- 0.03 ng/ml, gain of the respiratory controller (G) 0.42 - 0.1 l x min x Torr, and remifentanil blood effect site equilibration half-life (t(1/2)ke0) 0.53 +/- 0.2 min. Propofol caused a 20-50% reduction of C50 and G but had no effect on t(1/2)ke0. Apnea occurred during propofol infusion only. A simulation study revealed an increase in apnea duration at infusion speeds of 2.5-0.5 ng x ml x min followed by a reduction. At an infusion speed of < or = 0.31 ng x ml x min, no apnea was seen. Conclusions The effect of varying remifentanil infusions with and without a background of low-dose propofol on ventilation and end-tidal partial pressure of carbon dioxide concentration was described successfully using a non-steady-state model of the ventilatory control system. The model allows meaningful simulations and predictions.

SOME ELECTRICAL CHARACTERISTICS OF SUCROSE-WASHED FROG SARTORIUS MUSCLE

1966 ◽  
Vol 44 (4) ◽  
pp. 663-674 ◽  
Author(s):  
G. W. Mainwood
Keyword(s):  
Carbon Dioxide ◽  
Transmembrane Potential ◽  
Sucrose Solution ◽  
Surrounding Medium ◽  
Carbon Dioxide Concentration ◽  
Specific Effect ◽  
Sartorius Muscle ◽  
Extracellular Potassium ◽  
Extracellular Potassium Concentration ◽  
Frog Sartorius

Transmembrane potential measurements were carried out with microelectrodes in frog sartorius muscles washed in buffered sucrose solution. After an initial fall the potential returns to a level determined by the extracellular potassium concentration. After about 20 minutes of washing, the cells develop a response to carbon dioxide dissolved in the surrounding medium. Increasing the extracellular carbon dioxide concentration leads to a reversible fall in transmembrane potential. This appears to be a specific effect of carbon dioxide since lowering the pH in the absence of CO2 does not cause a significant potential change. It is postulated that this effect may be due to an efflux of bicarbonate ions.

scholarly journals The Extent of Short-Term and Long-Term Compensation to Temperature Shown by Frog and Toad Sartorius Muscle

1984 ◽  
Vol 108 (1) ◽  
pp. 57-75 ◽  
Author(s):  
J. M. RENAUD ◽  
E. D. STEVENS
Keyword(s):  
Muscle Length ◽  
Mechanical Power ◽  
Acclimation Temperature ◽  
Sartorius Muscle ◽  
Short Term ◽  
Shortening Velocity ◽  
The Difference ◽  
Temperature Interaction ◽  
Tetanic Tension

The effect of pH at different temperatures was studied on the force-velocity characteristics of the sartorius muscle to estimate short-term compensation to temperature. The effect of thermal acclimation was also studied in order to estimate long-term compensation. A decrease in either pH or temperature reduced both tetanic tension and shortening velocity. There was a significant pH-temperature interaction for tetanic tension and for maximum mechanical power, but not for Vmax. It is shown that this pH-temperature interaction was large enough to provide a mechanism for short-term compensation only for the maximum strength (tetanic tension) in both species. Shortening velocities at small loads of the sartorius muscle of frogs and toads acclimated to 25 C were faster than those acclimated to 5 C. The difference between the two acclimation groups increased with test temperature and was almost 1 muscle length per second (m.l.s−1) at 25 C for both species. Acclimation temperature had no significant effect on tetanic tension or on maximum mechanical power at any of the test temperatures. It is proposed that the small capacity for long-term compensation in frog and toad sartorius muscles is related to the strategy employed during winter: frogs and toads hibernate.

scholarly journals The relation between sodium ion content and efflux of labelled sodium ions from yeast

1968 ◽  
Vol 107 (2) ◽  
pp. 265-271 ◽  
Author(s):  
Elizabeth Dee ◽  
Edward J. Conway
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Concentration ◽  
Sartorius Muscle ◽  
Free Medium ◽  
Ion Content ◽  
Frog Sartorius Muscle ◽  
Na Efflux ◽  
K Concentration ◽  
Frog Sartorius ◽  
External K

1. The activity of the Na+ pump in an Na+-rich yeast was compared with that in an Na+-rich frog sartorius muscle, and found to be very similar to it over the first hour if both were immersed in fluid containing 104mm-Na+ plus 10mm-K+. 2. The efflux of labelled Na+ from an Na+-rich yeast into an Na+-free medium was investigated. In this Na+-free medium, Li+ or choline replaced the Na+, and the efflux–content curves obtained with either of these ions were very similar. The curves were sigmoid, reaching or approaching a saturation at the higher internal Na+ concentrations. 3. The curves obtained with yeast resembled those similarly obtained with frog sartorius muscle by Keynes & Swan (1959), Mullins & Frumento (1963), Harris (1965) and Keynes (1965). The slope of the plot of the logarithm of the Na+ efflux against the logarithm of the Na+ concentration in the cells reached its highest value at an internal Na+ concentration of 15m-equiv./kg. (27m-equiv./l. of cell water). 4. The effect of external K+ concentration on the efflux–content relationship was examined. An increased K+ concentration was found to increase the Na+ efflux by raising the saturation value, which is similar to observations made by Harris (1965) with frog muscle. 5. The effect of increasing the external carbon dioxide concentration was investigated. No effect on the slope of the plot of the logarithm of the Na+ efflux against the logarithm of the Na+ content was noticed even when the yeast suspension was equilibrated with 100% carbon dioxide. There was, however, a decrease in the amount of Na+ efflux on equilibrating the solution with carbon dioxide.

Electrolyte secretion from rabbit pancreas in vitro

1965 ◽  
Vol 208 (6) ◽  
pp. 1171-1176 ◽  
Author(s):  
S. S. Rothman ◽  
F. P. Brooks
Keyword(s):  
Carbon Dioxide ◽  
Pancreatic Secretion ◽  
Chloride Concentration ◽  
Carbon Dioxide Concentration ◽  
Total Carbon ◽  
Bathing Solution ◽  
Vascular Perfusion ◽  
Secretory Rate ◽  
Plasma Filtration

A technic has been developed permitting direct collection of undiluted rabbit pancreatic secretion in vitro without vascular perfusion. The rates of secretion and output of electrolytes were comparable to those obtained in situ. When secretin was added, flow and bicarbonate concentration increased. Secretion in vitro ceased when inhibitors of glycolysis and aerobic metabolism were added to the bathing solution. The sodium concentration of the secretion exceeded that of the bathing solution in all but one observation. Potassium concentrations in secretion were linearly related (slope = 0.93) to the potassium concentration in the bath over a range of 5.8–12.0 mm. After 4–5 hr in vitro, the total carbon dioxide concentration of secretion had decreased while chloride concentration increased with no significant change in the rate of secretion. When secretory rate changed over a range of approximately 30–600 µliters/hr, chloride and carbon dioxide output varied directly with the rate of secretion. The osmolarity of the bathing solution and secretion were always equivalent. These results are incompatible with direct plasma filtration and bicarbonate-chloride exchange as the main mechanisms of pancreatic secretion.

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