scholarly journals In vitro Studies of the Gain and Exchange of Calcium in Frog Skeletal Muscle

1961 ◽  
Vol 44 (6) ◽  
pp. 1121-1130 ◽  
Author(s):  
Ethel Cosmos ◽  
Eric J. Harris
Keyword(s):  
Skeletal Muscle ◽  
In Vitro Studies ◽  
Frog Skeletal Muscle ◽  
Valid Measure ◽  
Frog Sartorius

(1) The Ca++, Na+, and K+ contents of frog sartorius muscles were found analytically after exposure to various media including some containing labeled Ca++. (2) During storage in media with 100 to 120 mM Na+ and 1 mM Ca++ both Na+ and Ca++ are gained while K+ is lost; there is a high correlation between Na+ and Ca++ gains. (3) When Ca++ gain occurs from a solution containing labeled Ca++ there is also some exchange of the original Ca++ with the labeled Ca++. The amount exchanged is considerably less (e.g. 50 per cent) than the total amount of labeled Ca++ taken up by the tissue. (4) When the external Na+ concentration is reduced to 30 mM the amount of labeled Ca++ taken up is increased. Part of the increase is attributable to a greater net gain and part to a greater degree of exchange. (5) It is pointed out that muscles which have been loaded in vitro with labeled Ca++ will not provide a valid measure of the exchangeability of the normal Ca++ content present at the time of dissection. (6) Comparison is made between results obtained using Sr89 and Ca45 as labels for the Ca++. Little, if any, difference is perceptible.

In vitro studies on the effect of glucocorticoids on the metabolism of perfused rat skeletal muscle

1984 ◽  
Vol 104 (4_Supplb) ◽  
pp. S110-S111
Author(s):  
P. SCHADEWALDT ◽  
H. MEYER
Keyword(s):  
Skeletal Muscle ◽  
In Vitro Studies ◽  
Rat Skeletal Muscle

scholarly journals Simultaneous measurement of Ca2+ in muscle with Ca electrodes and aequorin. Diffusible cytoplasmic constituent reduces Ca(2+)-independent luminescence of aequorin.

1991 ◽  
Vol 98 (6) ◽  
pp. 1141-1160 ◽  
Author(s):  
L A Blatter ◽  
J R Blinks
Keyword(s):  
Skeletal Muscle ◽  
Simultaneous Measurement ◽  
Light Emission ◽  
Ringer Solution ◽  
Light Signal ◽  
Frog Skeletal Muscle ◽  
Stable Level ◽  
Total Absence ◽  
Normal Ringer

Estimates of cytoplasmic Ca2+ concentration ([Ca2+]i) were made essentially simultaneously in the same intact frog skeletal muscle fibers with aequorin and with Ca-selective microelectrodes. In healthy fibers under truly resting conditions [Ca2+]i was too low to be measured reliably with either technique. The calibration curves for both indicators were essentially flat in this range of [Ca2+], and the aequorin light signal was uniformly below the level to be expected in the total absence of Ca2+. When [Ca2+]i had been raised to a stable level below the threshold for contracture by increasing [K+]o to 12.5 mM, [Ca2+]i was 38 nM according to aequorin and 59 nM according to the Ca-selective microelectrodes. These values are not significantly different. Our estimates of [Ca2+]i are lower than most others obtained with microelectrodes, probably because the presence of aequorin in the cells allowed us to detect damaging microelectrode impalements that otherwise we would have had no reason to reject. The observation that the light emission from aequorin-injected fibers in normal Ringer solution was below the level expected from the Ca(2+)-independent luminescence of aequorin in vitro was investigated further, with the conclusion that the myoplasm contains a diffusible macromolecule (between 10 and 30 kD) that interacts with aequorin to reduce light emission in the absence of Ca2+.

scholarly journals In Vitro Study of Mechanical and Kinetic Properties of Myosin II from Frog Skeletal Muscle

2009 ◽  
Vol 96 (3) ◽  
pp. 614a
Author(s):  
Ravikrishnan Elangovan ◽  
Marco Capitanio ◽  
Francesco S. Pavone ◽  
Vincenzo Lombardi
Keyword(s):  
Skeletal Muscle ◽  
Myosin Ii ◽  
In Vitro Study ◽  
Vitro Study ◽  
Kinetic Properties ◽  
Frog Skeletal Muscle

An investigation of the activity of opiate drug receptors located on frog skeletal muscle fibre membrane

1978 ◽  
Vol 56 (3) ◽  
pp. 501-508 ◽  
Author(s):  
G. B. Frank ◽  
J. Marwaha
Keyword(s):  
Skeletal Muscle ◽  
Action Potentials ◽  
Skeletal Muscle Fibre ◽  
Second Phase ◽  
Frog Skeletal Muscle ◽  
Potential Production ◽  
Low Concentrations ◽  
Drug Receptors ◽  
Frog Sartorius ◽  
Opiate Drug

Extracellular and intracellular microelcctrode studies were conducted to test the actions and interactions of opiate agonists, antagonists, and procaine on action potentials in frog sartorius muscles. Extracellular studies showed that morphine, methadone, propoxyphene, and procaine all depressed action potential production. Low concentrations of naloxone or naltrexone antagonized the excitability depression produced by the three opiate agonists but not the depression produced by procaine. Intracellular studies revealed that certain concentrations of the opiate agonists produced a biphasic decline in the stimulus-induced increase in sodium conductance (gNa). Naloxone or naltrexone antagonized only the second phase of this decline. These results show that part of the excitability depression produced by opiate agonists is due to an action on opiate drug receptors.

scholarly journals Myoplasmic calcium transients in intact frog skeletal muscle fibers monitored with the fluorescent indicator furaptra.

1991 ◽  
Vol 97 (2) ◽  
pp. 271-301 ◽  
Author(s):  
M Konishi ◽  
S Hollingworth ◽  
A B Harkins ◽  
S M Baylor
Keyword(s):  
Skeletal Muscle ◽  
Time Course ◽  
Dissociation Constants ◽  
Diffusion Constant ◽  
Preceding Paper ◽  
Excitation Wavelength ◽  
Frog Skeletal Muscle ◽  
Fluorescent Indicator ◽  
Single Action

Furaptra (Raju, B., E. Murphy, L. A. Levy, R. D. Hall, and R. E. London. 1989. Am. J. Physiol. 256:C540-C548) is a "tri-carboxylate" fluorescent indicator with a chromophore group similar to that of fura-2 (Grynkiewicz, G., M. Poenie, and R. Y. Tsien. 1985. J. Biol. Chem. 260:3440-3450). In vitro calibrations indicate that furaptra reacts with Ca2+ and Mg2+ with 1:1 stoichiometry, with dissociation constants of 44 microM and 5.3 mM, respectively (16-17 degrees C; ionic strength, 0.15 M; pH, 7.0). Thus, in a frog skeletal muscle fiber stimulated electrically, the indicator is expected to respond to the change in myoplasmic free [Ca2+] (delta[Ca2+]) with little interference from changes in myoplasmic free [Mg2+]. The apparent longitudinal diffusion constant of furaptra in myoplasm was found to be 0.68 (+/- 0.02, SEM) x 10(-6) cm2 s-1 (16-16.5 degrees C), a value which suggests that about half of the indicator was bound to myoplasmic constituents of large molecular weight. Muscle membranes (surface and/or transverse-tubular) appear to have some permeability to furaptra, as the total quantity of indicator contained within a fiber decreased after injection; the average time constant of the loss was 302 (+/- 145, SEM) min. In fibers containing less than 0.5 mM furaptra and stimulated by a single action potential, the calibrated peak value of delta[Ca2+] averaged 5.1 (+/- 0.3, SEM) microM. This value is about half that reported in the preceding paper (9.4 microM; Konishi, M., and S. M. Baylor. 1991. J. Gen. Physiol. 97:245-270) for fibers injected with purpurate-diacetic acid (PDAA). The latter difference may be explained, at least in part, by the likelihood that the effective dissociation constant of furaptra for Ca2+ is larger in vivo than in vitro, owing to the binding of the indicator to myoplasmic constituents. The time course of furaptra's delta[Ca2+], with average values (+/- SEM) for time to peak and half-width of 6.3 (+/- 0.1) and 9.5 (+/- 0.4) ms, respectively, is very similar to that of delta[Ca2+] recorded with PDAA. Since furaptra's delta[Ca2+] can be recorded at a single excitation wavelength (e.g., 420 nm) with little interference from fiber intrinsic changes, movement artifacts, or delta[Mg2+], furaptra represents a useful myoplasmic Ca2+ indicator, with properties complementary to those of other available indicators.

Qualitative measurements of the entry of L-lactate into single surface fibres of frog skeletal muscle using a lactate-sensitive microelectrode

1987 ◽  
Vol 65 (12) ◽  
pp. 2488-2491 ◽  
Author(s):  
M. J. Mason
Keyword(s):  
Skeletal Muscle ◽  
Lactate Concentration ◽  
Ion Exchanger ◽  
Sartorius Muscle ◽  
Muscle Fibres ◽  
Frog Skeletal Muscle ◽  
Frog Sartorius Muscle ◽  
Frog Sartorius ◽  
Qualitative Measurements ◽  
Liquid Ion Exchanger

The present results demonstrate the sensitivity of the Corning chloride liquid ion exchanger 477913 to L-lactate. Microelectrodes filled with this exchanger showed responses to changes in L-lactate concentration in chloride-free solutions. In these experiments L-lactate replaced gluconate in equimolar amounts. Microelectrodes filled with this exchanger were used to qualitatively detect changes in intracellular anion in chloride-depleted frog sartorius muscle fibres during exposure to extracellular concentrations of L-lactate. The increase in intracellular anion concentration is consistent with the movement of L-lactate into the cell. This microelectrode enables one to qualitatively monitor changes in intracellular L-lactate in chloride-free experiments without incorporating selectivity coefficients.

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