scholarly journals The Mechanism of Dual Responsiveness in Muscle Fibers of the Grasshopper Romalea microptera

1959 ◽  
Vol 43 (2) ◽  
pp. 377-395 ◽  
Author(s):  
J. A. Cerf ◽  
H. Grundfest ◽  
G. Hoyle ◽  
Frances V. McCann
Keyword(s):  
Membrane Potential ◽  
Muscle Fiber ◽  
Refractory Period ◽  
Muscle Fibers ◽  
Fiber Membrane ◽  
Graded Responses ◽  
Functional Aspects ◽  
Graded Activity ◽  
The Individual ◽  
Stimulation Of

Dually innervated Romalea muscle fibers which respond differently to stimulation of their fast and slow axons are excited by intracellularly applied depolarizing stimuli. The responses, though spike-like in appearance, are graded in amplitude depending upon the strength of the stimuli and do not exceed about 30 mv. in height. In other respects, however, these graded responses possess properties that are characteristic of electrically excitable activity: vanishingly brief latency; refractoriness; a post-spike undershoot. They are blocked by hyperpolarizing the fiber membrane; respond repetitively to prolonged depolarization, and are subject to depolarizing inactivation. As graded activity, these responses propagate decrementally. The fast and slow axons of the dually responsive muscle fibers initiate respectively large and small postsynaptic potentials (p.s.p.'s) in the muscle fiber. These responses possess properties that characterize electrically inexcitable depolarizing activity. They are augmented by hyperpolarization and diminished by depolarization. Their latency is independent of the membrane potential. They have no refractory period, thus being capable of summation. The fast p.s.p. evokes a considerable or maximal electrically excitable response. The combination, which resembles a spike, leads to a twitch-like contraction of the muscle fiber. The individual slow p.s.p.'s elicit no or only little electrically excitable responses, and they evoke slower smaller contractile responses. The functional aspects of dual responsiveness and the several aspects of the theoretical importance of the gradedly responsive, electrically excitable component are discussed.

scholarly journals Graded responses of human neutrophils induced by serum-treated zymosan

Blood ◽  
1985 ◽  
Vol 66 (5) ◽  
pp. 1182-1188 ◽  
Author(s):  
JC Whitin ◽  
DH Ryan ◽  
HJ Cohen
Keyword(s):  
Flow Cytometry ◽  
Membrane Potential ◽  
Fluorescent Probe ◽  
Dose Response ◽  
Dose Dependence ◽  
Human Neutrophils ◽  
Graded Responses ◽  
Dose Dependent ◽  
O2 Production ◽  
Stimulation Of

Abstract A modified zymosan preparation was used to probe the interaction of particulate stimuli with human neutrophils (PMNs). After extraction with alkali and detergent, the zymosan particles retained their ability to be opsonized in serum and to stimulate PMNs. Serum-treated zymosan (STZ) induced dose-dependent superoxide (O2-) production and membrane potential depolarization in the range of 1 to 10 mg/mL of STZ. The rate and extent of secretion of lysozyme and beta-glucuronidase were also dose-dependent in the range of 1 to 10 mg/mL of STZ. Cytochemical studies using nitroblue tetrazolium, however, showed that 92% of PMNs were stimulated to produce O2- at 0.1 mg/mL of STZ. The dose response of O2- production induced by STZ is therefore due to increasing O2- production by individual PMNs and not to the stimulation of more PMNs to produce O2-. Evidence for O2- production was found only in the area of PMN-zymosan contact, suggesting a mechanism for the graded responses of PMNs treated with particulate stimuli. In order to determine the nature of the dose dependence of depolarization (a measure of PMN activation), PMNs equilibrated with the fluorescent probe 3,3′- dipentyloxacarbocyanine were analyzed by flow cytometry. The results demonstrate that STZ induces a dose-dependent depolarization of the membrane potential of individual PMNs. These results also demonstrate that increasing concentrations of STZ can induce increasing PMN responses even when all of the PMNs have been activated. These results are consistent with the hypothesis that receptor-mediated particulate stimulation of PMNs is a phenomenon that results in graded PMN responses.

Stabilization and rectification of muscle fiber membrane by tetrodotoxin

1960 ◽  
Vol 198 (5) ◽  
pp. 934-938 ◽  
Author(s):  
Toshio Narahashi ◽  
Takehiko Deguchi ◽  
Norimoto Urakawa ◽  
Yoshio Ohkubo
Keyword(s):  
Muscle Fiber ◽  
Muscle Fibers ◽  
Membrane Resistance ◽  
Frog Muscle ◽  
Resting Potential ◽  
Fiber Membrane ◽  
Delayed Rectification ◽  
Intracellular Microelectrodes ◽  
Cathodal Current ◽  
Muscle Fiber Membrane

The mode of action of tetrodotoxin on the frog muscle fiber membrane has been analyzed with the aid of intracellular microelectrodes. Tetrodotoxin of 10–7 concentration made the applied cathodal current ineffective in producing action potential, whereas the resting potential and resting membrane resistance underwent little or no change. With 10–8 tetrodotoxin the muscle fibers responded with the small action potentials at high critical depolarizations. These results can be explained on the basis of the membrane being stabilized by inactivation of the sodium-carrying mechanism. Although delayed rectification was not observed in normal muscle fibers, it became apparent in the fibers rendered inexcitable by tetrodotoxin. This finding, together with other evidence in the existing literature, supports an applicability of the sodium theory to the frog muscle fibers.

Influence of nitrate and other anions on fast and slow contractions of crab muscle

1968 ◽  
Vol 46 (1) ◽  
pp. 1-9 ◽  
Author(s):  
H. L. Atwood
Keyword(s):  
Membrane Potential ◽  
Muscle Fiber ◽  
Membrane Resistance ◽  
Single Muscle ◽  
Fiber Membrane ◽  
Tension Development ◽  
Muscle Fiber Membrane ◽  
Slow Contraction ◽  
Potential Threshold ◽  
Bathing Fluid

The effects of bromide, nitrate, iodide, and thiocyanate ions on the neurally evoked fast and slow contractions of a crab muscle were investigated. Both types of contraction were depressed in bromide and nitrate. In iodide and thiocyanate, the slow contraction was often depressed but the fast contraction was potentiated. The foreign anions increased muscle fiber membrane resistance and the amplitudes of both fast and slow postsynaptic potentials. Records of tension development in single muscle fibers showed that more stimulating current was required to produce a given tension in nitrate than in the standard bathing fluid; this change was related to hyperpolarization of the muscle fiber membrane in nitrate. Potassium contractures also were inhibited by nitrate, because of the less effective depolarization of the cell membrane by potassium ion in the presence of nitrate. No marked shift in the membrane potential threshold for contraction occurred after treatment with the foreign anions.

Potassium activation and K spikes in muscle fibers of the mealworm larva (Tenebrio molitor)

1962 ◽  
Vol 203 (3) ◽  
pp. 588-594 ◽  
Author(s):  
Peter Belton ◽  
Harry Grundfest
Keyword(s):  
Muscle Fiber ◽  
Muscle Fibers ◽  
Membrane Conductance ◽  
Tenebrio Molitor ◽  
Resting Potential ◽  
Terminal Portion ◽  
Graded Responses ◽  
High K ◽  
Wide Range ◽  
Electrical Stimuli

Muscle fibers of larval mealworms ( Tenebrio molitor) can be set to a wide range of resting potentials (ca. –40 to –90 mv), while remaining responsive to electrical stimuli. The initial resting potential is maintained long after K+0 is increased to levels well above the normal value (ca. 40 mEq/liter). However, spikes or graded responses are markedly affected by the level of K+0. For levels between 40 and 150 mEq/liter the terminal portion of the responses may become prolonged depolarizations, and for K+0 above about 200 mEq/liter positive overshoots occur. These changes follow the Nernst relation for K+0 > 20 mEq/liter. Thus, the membrane of the muscle fiber at rest is not a K electrode, but changes to the latter state during a response, indicating occurrence of K activation. The "K spikes" which develop in high K+0 lack an early depolarizing component, which is comparable to that subsumed under the Na activation and inactivation processes of the Hodgkin-Huxley theory. The K spikes may last for many seconds and are associated with increased membrane conductance throughout this time. The K spikes are probably terminated by a process of depolarizing K inactivation.

Innervation and reinnervation of cricothyroid muscle in the rabbit

1961 ◽  
Vol 201 (6) ◽  
pp. 1199-1202 ◽  
Author(s):  
A. Van Harreveld ◽  
S. Tachibana
Keyword(s):  
Muscle Fiber ◽  
Intracellular Recording ◽  
Muscle Fibers ◽  
Cricothyroid Muscle ◽  
Motor Nerves ◽  
Polyneuronal Innervation ◽  
Stimulation Of

The m. cricothyroideus of the rabbit is innervated by two motor nerves (n. laryngeus superior and n. laryngeus medius). No indication of extensive polyneuronal innervation was found in gold stained isolated muscle fibers and groups of fibers. Double end plates were found on about 2.5% of the fibers. It could not be ascertained whether they were supplied by different motor fibers or by branches of the same fiber. Intracellularly recorded spike potentials were observed in the same muscle fiber by stimulation of the two motor nerves in 6% of the fibers examined. The use of intracellular recording as a criterion for polyneuronal innervation was discussed. After resection of the n. laryngeus medius a fargoing reinnervation of the muscle by the n. laryngeus superior takes place.

scholarly journals Permeability of Alkali Metal Cations in Lobster Muscle

1968 ◽  
Vol 51 (3) ◽  
pp. 399-425 ◽  
Author(s):  
Harold Gainer ◽  
Harry Grundfest
Keyword(s):  
Membrane Potential ◽  
Muscle Fiber ◽  
Single Muscle ◽  
Alkali Metal Cations ◽  
Fiber Membrane ◽  
Osmotic Permeability ◽  
Hyperosmotic Condition ◽  
Time Courses ◽  
Muscle Fiber Membrane ◽  
External K

Single muscle fibers from lobster walking legs are effectively impermeable to Na, but are permeable to K. They shrink in hyperosmotic NaCl; they swell in low NaCl media which are hyposmotic or which are made isosmotic with the addition of KCl. In conformity, the membrane potential is relatively insensitive to changes in external Na, while it responds according to the Nernst relation for changes in external K. When the medium is made isosmotic or hyperosmotic with RbCl the volume and membrane potential changes are of essentially the same magnitudes as those in media enriched with KCl. The time courses for attaining equilibrium are slower, indicating that Rb is less permeant than K. Substitution of CsCl for NaCl (isosmotic condition) produces no change in volume of the muscle fiber. Addition of CsCl (hyperosmotic condition) causes a shrinkage which attains a steady state, as is the case in hyperosmotic NaCl. Osmotically, therefore, Cs appears to be no more permeant than is Na. However, the membrane depolarizes slowly in Cs-enriched media and eventually comes to behave as an ideal Cs electrode. Thus, the electrode properties of the lobster muscle fiber membrane may not depend upon the diffusional relations of the membrane and ions, and the osmotic permeability of the membrane for a given cation may not correspond with the electrophysiologically deduced permeability. Comparative data on the effects of NH4 and Li are also included and indicate several other degrees of complexity in the cell membrane.

scholarly journals Length-dependent electromechanical coupling in single muscle fibers.

1976 ◽  
Vol 68 (6) ◽  
pp. 653-669 ◽  
Author(s):  
A M Gordon ◽  
E B Ridgway
Keyword(s):  
Membrane Potential ◽  
Calcium Release ◽  
Muscle Fibers ◽  
Membrane Properties ◽  
Constant Current ◽  
Equilibrium Potential ◽  
Muscle Membrane ◽  
Single Muscle ◽  
Fiber Membrane ◽  
Length Dependence

In single muscle fibers from the giant barnacle, a small decrease in muscle length decreases both the calcium activation and the peak isometric tension produced by a constant current stimulus. The effect is most pronounced if the length change immediately precedes the stimulation. In some cases, the decrease in tension with shortening can be accounted for almost entirely by a decrease in calcium release rather than changes in mechanical factors such as filament geometry. During the constant current stimulation the muscle membrane becomes more depolarized at longer muscle lengths than at the shorter muscle lengths. Under voltage clamp conditions, when the membrane potential is kept constant during stimulation, there is little length dependence of calcium release. Thus, the effect of length on calcium release is mediated through a change in membrane properties, rather than an effect on a subsequent step in excitation-contraction coupling. Stretch causes the unstimulated fiber membrane to depolarize by about l mV while release causes the fiber membrane to hyperpolarize by about the same amount. The process causing this change in potential has an equilibrium potential nearly 10 mV hyperpolarized from the resting level. This change in resting membrane potential with length may account for the length dependence of calcium release.

scholarly journals Graded responses of human neutrophils induced by serum-treated zymosan

Blood ◽  
1985 ◽  
Vol 66 (5) ◽  
pp. 1182-1188
Author(s):  
JC Whitin ◽  
DH Ryan ◽  
HJ Cohen
Keyword(s):  
Flow Cytometry ◽  
Membrane Potential ◽  
Fluorescent Probe ◽  
Dose Response ◽  
Dose Dependence ◽  
Human Neutrophils ◽  
Graded Responses ◽  
Dose Dependent ◽  
O2 Production ◽  
Stimulation Of

A modified zymosan preparation was used to probe the interaction of particulate stimuli with human neutrophils (PMNs). After extraction with alkali and detergent, the zymosan particles retained their ability to be opsonized in serum and to stimulate PMNs. Serum-treated zymosan (STZ) induced dose-dependent superoxide (O2-) production and membrane potential depolarization in the range of 1 to 10 mg/mL of STZ. The rate and extent of secretion of lysozyme and beta-glucuronidase were also dose-dependent in the range of 1 to 10 mg/mL of STZ. Cytochemical studies using nitroblue tetrazolium, however, showed that 92% of PMNs were stimulated to produce O2- at 0.1 mg/mL of STZ. The dose response of O2- production induced by STZ is therefore due to increasing O2- production by individual PMNs and not to the stimulation of more PMNs to produce O2-. Evidence for O2- production was found only in the area of PMN-zymosan contact, suggesting a mechanism for the graded responses of PMNs treated with particulate stimuli. In order to determine the nature of the dose dependence of depolarization (a measure of PMN activation), PMNs equilibrated with the fluorescent probe 3,3′- dipentyloxacarbocyanine were analyzed by flow cytometry. The results demonstrate that STZ induces a dose-dependent depolarization of the membrane potential of individual PMNs. These results also demonstrate that increasing concentrations of STZ can induce increasing PMN responses even when all of the PMNs have been activated. These results are consistent with the hypothesis that receptor-mediated particulate stimulation of PMNs is a phenomenon that results in graded PMN responses.

Physiological, morphological, and histochemical properties of cat external anal sphincter

1988 ◽  
Vol 255 (6) ◽  
pp. G772-G778 ◽  
Author(s):  
J. Krier ◽  
T. Adams ◽  
R. A. Meyer
Keyword(s):  
Muscle Fiber ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Succinic Dehydrogenase ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Motor Axons ◽  
Fast Twitch Muscle ◽  
Fast Twitch ◽  
Stimulation Of

The contractile properties, morphology, and the distribution of striated muscle fiber types of the external and sphincter (EAS) were determined using axial force measurements, fiber size cross-sectional area measurements, and histochemistry. Electrical stimulation of motor axons in pudendal nerve at supramaximal intensities (10 V, 0.05 ms duration) elicited twitch contractions of EAS. The time to peak force after a single pulse ranged from 37 to 42 ms. The time for relaxation to half-maximal twitch force ranged from 20 to 29 ms. Repetitive stimulation of motor axons (0.1-3.0 Hz) produced potentiation and fatigue of single twitch contractile force, suggesting that the EAS of the cat is comprised predominantly of fast-twitch muscle fibers. Confirmation of skeletal muscle fiber types was determined by histochemistry. Frozen serial cross sections of EAS were incubated to demonstrate succinic dehydrogenase (SDH) and myosin adenosine triphosphatase after alkaline preincubation (pH 10.4). Based on these reactions, muscle fibers were classified as fast glycolytic (FG) (high ATPase, low SDH), fast oxidative-glycolytic (FOG) (high ATPase, high SDH), and slow oxidative (SO) (low ATPase, high SDH). The mean percentage +/- SE of each histochemical type was the following: FG, 73.5 +/- 3.9; FOG, 22.8 +/- 3.7; and SO, 3.7 +/- 0.6. These results indicate that the predominant fiber type for the EAS is FG. The EAS of the cat is considered a nominally fast-twitch muscle.

scholarly journals Testing the Classification of Static γ Axons Using Different Patterns of Random Stimulation

1999 ◽  
Vol 81 (6) ◽  
pp. 2823-2832 ◽  
Author(s):  
Julien Petit ◽  
Robert W. Banks ◽  
Yves Laporte
Keyword(s):  
Muscle Fiber ◽  
Muscle Fibers ◽  
Muscle Spindles ◽  
Intrafusal Fiber ◽  
Intrafusal Muscle ◽  
Intrafusal Muscle Fibers ◽  
Initial Peak ◽  
Stimulation Of ◽  
Intrafusal Muscle Fiber

Testing the classification of static γ axons using different patterns of random stimulation. The possibility of using randomly generated stimulus intervals (with a Poisson distribution) to identify the type(s) of intrafusal fiber activated by the stimulation of single static γ axons was tested in Peroneus tertius muscle spindles of anesthetized cats. Three patterns of random stimulation with different values of mean intervals [20 ± 4.47, 30 ± 8.94, and 40 ± 8.94 (SD) ms] were used. Single static γ axons activating, in single spindles, either the bag2 fiber alone or the chain fibers alone or both types of intrafusal fiber were prepared. Responses of spindle primary endings elicited by the stimulation of γ axons were recorded from Ia fibers in cut dorsal root filaments. Cross-correlograms between stimuli and spikes of the primary ending responses, autocorrelograms, interval histograms of responses, and stimulations were built. The characteristics of cross-correlograms were found to be related not only to the type of intrafusal muscle fibers activated but also to the parameters of the stimulation. Moreover some cross-correlograms with similar characteristics were produced by the activation of different intrafusal muscle fibers. It also was observed that, whatever the type of intrafusal muscle fiber activated, cross-correlograms could exhibit oscillations after an initial peak, provided the extent in frequency of the primary ending response was small; these oscillations arise in part from the autocorrelation of the primary ending responses. Therefore, cross-correlograms obtained during random stimulation of static γ axons cannot be used for unequivocally identifying the type(s) of intrafusal muscle fiber these axons supply.

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