Actions of acridine compounds and barium ions on action potentials of frog muscle fibers

Life Sciences ◽  
1970 ◽  
Vol 9 (13) ◽  
pp. 753-758 ◽  
Author(s):  
Robert L. Volle
Keyword(s):  
Action Potentials ◽  
Muscle Fibers ◽  
Frog Muscle ◽  
Barium Ions

scholarly journals Potentiometric measurement of membrane action potentials in frog muscle fibres

1966 ◽  
Vol 183 (1) ◽  
pp. 152-166 ◽  
Author(s):  
B. Frankenhaeuser ◽  
B. D. Lindley ◽  
R. S. Smith
Keyword(s):  
Action Potentials ◽  
Frog Muscle ◽  
Muscle Fibres ◽  
Membrane Action ◽  
Potentiometric Measurement

scholarly journals Globular and asymmetric acetylcholinesterase in frog muscle basal lamina sheaths.

1986 ◽  
Vol 102 (3) ◽  
pp. 762-768 ◽  
Author(s):  
M Nicolet ◽  
M Pinçon-Raymond ◽  
F Rieger
Keyword(s):  
Basal Lamina ◽  
Acetylcholine Receptors ◽  
Muscle Fibers ◽  
Frog Muscle ◽  
Motor Endplate ◽  
Molecular Forms ◽  
Nonionic Detergent ◽  
Plasmic Membrane ◽  
Triton X

After denervation in vivo, the frog cutaneus pectoris muscle can be led to degenerate by sectioning the muscle fibers on both sides of the region rich in motor endplate, leaving, 2 wk later, a muscle bridge containing the basal lamina (BL) sheaths of the muscle fibers (28). This preparation still contains various tissue remnants and some acetylcholine receptor-containing membranes. A further mild extraction by Triton X-100, a nonionic detergent, gives a pure BL sheath preparation, devoid of acetylcholine receptors. At the electron microscope level, this latter preparation is essentially composed of the muscle BL with no attached plasmic membrane and cellular component originating from Schwann cells or macrophages. Acetylcholinesterase is still present in high amounts in this BL sheath preparation. In both preparations, five major molecular forms (18, 14, 11, 6, and 3.5 S) can be identified that have either an asymmetric or a globular character. Their relative amount is found to be very similar in the BL and in the motor endplate-rich region of control muscle. Thus, observations show that all acetylcholinesterase forms can be accumulated in frog muscle BL.

Inhibition of Zn2+-induced potentiation of twitch tension by Ni2+ in frog muscle

1986 ◽  
Vol 64 (5) ◽  
pp. 625-630
Author(s):  
Toshiharu Oba ◽  
Ken Hotta
Keyword(s):  
Action Potential ◽  
Inhibitory Action ◽  
Channel Blocker ◽  
Rana Catesbeiana ◽  
Muscle Fibers ◽  
Frog Muscle ◽  
Duration Of Action ◽  
Ringer’S Solution ◽  
Mechanical Threshold ◽  
T Tubules

Effect of Ni2+ on Zn2+-induced potentiation of twitch tension was studied electrophysiologically in the toe muscle fibers of Rana catesbeiana. The major findings of this investigation are as follows. When 2 mM Ni2+ was applied to fibers in a normal Ringer's solution containing 50 μM Zn2+ (Zn2+ solution), the Zn2+-potentiated twitch tension decreased remarkably to about one-third of that before Ni2+ treatment. This concentration of Ni2+ caused a 23% decrease in the duration of action potential which had been prolonged by Zn2+ (6.61–5.09 ms). Ni2+ (2 mM) added to normal Ringer's solution led to increases of about 30 and 42% in twitch tension and in the duration of action potential, respectively. A slight increase in the mechanical threshold was induced by 2 mM Ni2+. The inhibitory action of Ni2+ on the twitch tension in Zn2+ solution was larger than that in the case of tetanus tension. Diltiazem (40 μM), aCa2+ channel blocker, did not inhibit the twitch tension potentiated in Zn2+ solution. These results suggest that the decrease in Zn2+-potentiated twitch tension by Ni2+ may possibly derive from impairment of the propagation of action potential along the T tubules.

Transient changes in intracellular calcium associated with a prolonged increase in excitability in neurons of Aplysia californica

1994 ◽  
Vol 71 (3) ◽  
pp. 1254-1257 ◽  
Author(s):  
T. E. Fisher ◽  
S. Levy ◽  
L. K. Kaczmarek
Keyword(s):  
Intracellular Calcium ◽  
Action Potentials ◽  
Calcium Release ◽  
External Medium ◽  
Aplysia Californica ◽  
Spontaneous Firing ◽  
Barium Ions ◽  
Transient Elevation ◽  
Bag Cell Neurons ◽  
Stimulation Of

1. Transient stimulation of an afferent input to the bag cell neurons of Aplysia californica triggers a 30-min period of spontaneous firing termed the afterdischarge. Measurement of free calcium ion concentrations using calcium-sensitive electrodes revealed a biphasic pattern of elevation of intracellular calcium levels during the afterdischarge. Basal calcium levels at the soma were found to rise rapidly during afferent stimulation and then to decline before the onset of spontaneous firing. This early peak in intracellular calcium was followed by a slower, transient elevation of calcium levels during the period of rapid firing that occurs in the first few minutes of afterdischarge. Stimulation of clusters of bag cell neurons in a calcium-free external medium failed to trigger afterdischarge and produced no changes in basal intracellular calcium levels. 2. When calcium ions in the external medium were replaced by barium ions, stimulation of clusters of bag cell neurons triggered afterdischarges that were characterized by long-duration action potentials. Intracellular calcium levels during these afterdischarges rose slowly over the first few minutes of spontaneous firing. Because calcium-sensitive microelectrodes do not respond to barium ions, these data suggest that stimulation of afterdischarge triggers calcium release from an intracellular compartment. 3. During afterdischarges in barium-containing external media, each broadened action potential produced a discrete transient elevation of intracellular calcium levels. A similar effect was observed in isolated bag cell neurons in primary culture when action potentials were stimulated by depolarizing current pulses in a barium-containing medium. These data suggest that, under these conditions, individual action potentials trigger the release of intracellular calcium from some intracellular pool.

Generation of action potentials in intermediate muscle fibers of frogs

1970 ◽  
Vol 4 (4) ◽  
pp. 109-116
Author(s):  
N. F. Skorobovichuk ◽  
L. V. Filippova
Keyword(s):  
Action Potentials ◽  
Muscle Fibers

Encoder response of isolated frog muscle spindle elicited by pseudorandom noise stimuli

1986 ◽  
Vol 55 (1) ◽  
pp. 13-22 ◽  
Author(s):  
H. Querfurth
Keyword(s):  
Muscle Spindle ◽  
Action Potentials ◽  
Dynamic Range ◽  
Frog Muscle ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Pseudorandom Noise ◽  
Afferent Discharge ◽  
The Mean ◽  
Discharge Patterns

The present experiments investigated the signal transfer in the isolated frog muscle spindle by using pseudorandom noise (PRN) as the analytical probe. In order to guarantee that the random stimulus covered the entire dynamic range of the receptor, PRN stimuli of different intensities were applied around a constant mean length, or PRN stimuli of the same intensity were used while varying the mean length of the spindle. Subthreshold receptor potentials, local responses, and propagated action potentials were recorded simultaneously from the first Ranvier node of the afferent stem fiber, thus providing detailed insight into the spike-initiating process within a sensory receptor. Relevant features of the PRN stimulus were evaluated by a preresponse averaging technique. Up to tau = 2 ms before each action potential the encoder selected a small set of steeply rising stretch transients. A second component of the preresponse stimulus ensemble (tau = 2-5 ms) opposed the overall stretch bias. Since each steeply rising stretch transient evoked a steeply rising receptor potential that guaranteed the critical slope condition of the encoding site, this stimulus profile was most effective in initiating action potentials. The dynamic range of the muscle spindle receptor extended from resting length, L0, to about L0 + 100 microns. At the lower limit (L0) the encoding membrane was depolarized to its firing level and discharged action potentials spontaneously. When random stretches larger than the upper region of the dynamic range were applied, the spindle discharged at the maximum impulse rate and displayed no depolarization block or "overstretch" phenomenon. Random stretches applied within the dynamic range evoked regular discharge patterns that were firmly coupled to the PRN. The afferent discharge rate increased, and the precision of phase-locking improved when the intensity of the PRN stimulus was increased around a constant mean stretch; or the mean prestretch level was raised to higher values while the intensity of the PRN stimulus was kept constant. In the case when the PRN stimulus covered the entire dynamic range, the temporal pattern of the afferent discharge remained constant for at least 10 consecutive sequences of PRN. A spectral analysis of the discharge patterns averaged over several sequences of PRN was employed. At the same stimulus intensity the response spectra displayed low-pass filter characteristics with a 10-dB bandwidth of 300 Hz and a high-frequency slope of -12 dB/oct. Increasing the mean intensity of the PRN stimulus or raising the prestretch level increased the response power.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Ultraslow contractile inactivation in frog skeletal muscle fibers.

1990 ◽  
Vol 96 (1) ◽  
pp. 47-56 ◽  
Author(s):  
C Caputo ◽  
P Bolaños
Keyword(s):  
Skeletal Muscle ◽  
Time Course ◽  
Muscle Fibers ◽  
Membrane Depolarization ◽  
Frog Muscle ◽  
Slow Time ◽  
Inactivation Curve ◽  
Lanthanum Ions ◽  
Skeletal Muscle Fibers ◽  
Spontaneous Relaxation

After a contracture response, skeletal muscle fibers enter into a state of contractile refractoriness or inactivation. Contractile inactivation starts soon after membrane depolarization, and causes spontaneous relaxation from the contracture response. Here we demonstrate that contractile inactivation continues to develop for tens of seconds if the membrane remains in a depolarized state. We have studied this phenomenon using short (1.5 mm) frog muscle fibers dissected from the Lumbricalis brevis muscles of the frog, with a two-microelectrode voltage-clamp technique. After a contracture caused by membrane depolarization to 0 mV, from a holding potential of -100 mV, a second contracture can be developed only if the membrane is repolarized beyond a determined potential value for a certain period of time. We have used a repriming protocol of 1 or 2 s at -100 mV. After this repriming period a fiber, if depolarized again to 0 mV, may develop a second contracture, whose magnitude and time course will depend on the duration of the period during which the fiber was maintained at 0 mV before the repriming process. With this procedure it is possible to demonstrate that the inactivation process builds up with a very slow time course, with a half time of approximately 35 s and completion in greater than 100 s. After prolonged depolarizations (greater than 100 s), the repriming time course is slower and the inactivation curve (obtained by plotting the extent of repriming against the repriming membrane potential) is shifted toward more negative potentials by greater than 30 mV when compared with similar curves obtained after shorter depolarizing periods (10-30 s). These results indicate that important changes occur in the physical state of the molecular moiety that is responsible for the inactivation phenomenon. The shift of the inactivation curve can be partially reversed by a low concentration (50 microM) of lanthanum ions. In the presence of 0.5 mM caffeine, larger responses can be obtained even after prolonged depolarization periods, indicating that the fibers maintain their capacity to liberate calcium.

Effects of BAPTA on force and Ca2+ transient during isometric contraction of frog muscle fibers

1998 ◽  
Vol 275 (2) ◽  
pp. C375-C381 ◽  
Author(s):  
Y.-B. Sun ◽  
C. Caputo ◽  
K. A. P. Edman
Keyword(s):  
Mechanical Performance ◽  
Muscle Fibers ◽  
Frog Muscle ◽  
Clear Correlation ◽  
Bathing Solution ◽  
Control Value ◽  
Contractile System ◽  
Intracellular Ca ◽  
Cross Bridges ◽  
Reduced State

The effects of 1,2-bis(2-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid (BAPTA) on force and intracellular Ca2+ transient were studied during isometric twitches and tetanuses in single frog muscle fibers. BAPTA was added to the bathing solution in its permeant AM form (50 and 100 μM). There was no clear correlation between the changes in force and the changes in Ca2+ transient. Thus during twitch stimulation BAPTA did not suppress the Ca2+ transient until the force had been reduced to <50% of its control value. At the same time, the peak myoplasmic free Ca2+concentration reached during tetanic stimulation was markedly increased, whereas the force was slightly reduced by BAPTA. The effects of BAPTA were not duplicated by using another Ca2+ chelator, EGTA, indicating that BAPTA may act differently as a Ca2+ chelator. Stiffness measurements suggest that the decrease in mechanical performance in the presence of BAPTA is attributable to a reduced number of active cross bridges. The results could mean that BAPTA, under the conditions used, inhibits the binding of Ca2+ to troponin C resulting in a reduced state of activation of the contractile system.

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