The effect of caffeine and tetracaine on the time course of potassium contractures of single muscle fibres.

Caputo, Carlo

doi:10.1113/jphysiol.1976.sp011275

Cited by 71 publications

(117 citation statements)

References 25 publications

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“…A similar effect of 0.5 mM Ni2+ was observed on the long term effect of Ca2+ reduction (not shown here). These results agree with those of CAPUTO (1972CAPUTO ( , 1981, who indicated that Ni2+ can substitute for Ca2+ in excitation-contraction coupling (E-C coupling). Corresponding to the 5 and 10 mM Mg2+, 1 and 3 mM Ni2+ in low Ca2+ solution markedly inhibited the peak tensions of both components (Fig.…”

Section: Resultssupporting

confidence: 92%

“…CAPUTO (1981) assumed that external Ca2+ stabilizes one of the steps of E-C coupling that regulates Ca release from the SR. The results of CAPUTO (1972CAPUTO ( , 1981 and our present data indicate that Ni2+ can substitute for external Ca2+ in developing tension and in maintaining a normal time course of the secondary component (Fig. 4) and suggest that at least Ca influx (BIANCHI and SHANES, 1959;BIANCHI, 1968) or a slow inward Ca current (BEATY and STEFANI, 1976;STANFIELD, 1977;SANCHEZ and STEFANI, 1978) may be excluded from the possible mechanisms of the direct effect of external Ca2+ on K contractures STEFANI, 1981, 1982).…”

Section: Discussionmentioning

confidence: 52%

“…3c and 4c) may be explained from the viewpoint of the biphasic K contractures; such different effects may be due to the difference between the actions of these divalent cations on the activation mechanism of the initial component and those of the secondary component. CAPUTO (1972CAPUTO ( , 1981 and CAPUTO and FERNANDEZ DE BOLANOS (1979) have proposed a model to interpret the peak tension and the time course of K contractures in terms of an activation and an inactivation mechanism (Caputo model). LUTTGAU and SPIECKER (1979) and COTA and STEFANI (1981, 1982 explained the effect of external Cat + reduction and the effect of Mgt + on the Cat reduction according to this model.…”

Section: Discussionmentioning

confidence: 99%

“…These results indicate that external Ca2+ exerts a direct effect on the K contractures. On the other hand, CAPUTO (1972CAPUTO ( , 1981 showed that the marked shortening of the time course of K contractures caused by Ca2+ reduction is completely removed by Ni2+ and concluded that extracellular calcium does not play a direct role in maintaining the normal time course of K contractures. Thus, there is discrepancy among the views of LUTTGAU and SPIECKER (1979), STEFANI (1981, 1982), and CAPUTO (1972CAPUTO ( , 1981.…”

mentioning

confidence: 99%

“…On the other hand, CAPUTO (1972CAPUTO ( , 1981 showed that the marked shortening of the time course of K contractures caused by Ca2+ reduction is completely removed by Ni2+ and concluded that extracellular calcium does not play a direct role in maintaining the normal time course of K contractures. Thus, there is discrepancy among the views of LUTTGAU and SPIECKER (1979), STEFANI (1981, 1982), and CAPUTO (1972CAPUTO ( , 1981. The time course of K contractures is known to be biphasic (the initial and the secondary components) in frog single twitch muscle fibers (CosTANTIN, 1971;TAKAUJI et al, 1980TAKAUJI et al, , 1982b, and the secondary component is markedly inhibited by external Ca2+ reduction (TAKAUJI et a!.,1980).…”

mentioning

confidence: 99%

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Effects of external calcium reduction on biphasic potassium contractures and action of divalent cations on the calcium reduction in frog single twitch muscle fibers.

Tsutsuura¹,

Takauji²,

Nagai³

1984

Jpn.J.Physiol

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The effects of external Ca2+ reduction on the biphasic potassium (K) contractures and the action of divalent cations under conditions of the Ca2+ reduction were examined in detail, using frog single twitch muscle fibers. The peak tension of the initial component of 80 mM K+ contractures was greatly potentiated by exposing the fiber to low Ca2+ solution for 30 sec, and the degree of this potentiation was decreased with increasing the exposing time. In contrast, the peak tension of the secondary component was rapidly inhibited by Ca2+ reduction. The potentiation of the initial component was removed by 3 mM Mg2+ or 0.5 mM Ni2+. The inhibition of the secondary component, especially the shortening of its time course, was reversed partially by 3 mM Mg2 + and almost completely by 0.5 mM Ni2 + . The difference between the inhibitory effect of 10 mM Mg2+ or 1-3 mM Ni2+ on the initial component and that on the secondary component was also demonstrated. The tension development of the secondary component was completely inhibited by external Ca2+ reduction for 20 min, but it was observed in the presence of 3 mM Mg2+, although its time course was shorter. These results indicate that the actions of Mg2+ and Ni2+ on the initial component differ from those on the secondary component and suggest the possible mechanisms of the actions of these divalent cations on the biphasic K contractures.Key Words: frog single twitch muscle fiber, biphasic K contractures, external Ca2+ reduction, direct effect of Cat +, Mg2+ and Ni2+ effects. LUTTGAU and SPIECKER (1979) have recently reported that by external Ca2+ reduction in the presence of Mg2+, the peak tension of the maximum contractures is slightly affected, while the time course of the contractures is shortened. STEFANI (1981, 1982) reported that under the same conditions the peak con-

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Section: Resultssupporting

confidence: 92%

Section: Discussionmentioning

confidence: 52%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Effects of external calcium reduction on biphasic potassium contractures and action of divalent cations on the calcium reduction in frog single twitch muscle fibers.

Tsutsuura¹,

Takauji²,

Nagai³

1984

Jpn.J.Physiol

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Pharmacological Investigations of Excitation‐Contraction Coupling

Caputo

1983

Comprehensive Physiology

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The sections in this article are: Excitation‐Contraction Coupling Phenomena Active State Regulation of Calcium Release Mechanically Effective Period Contractile Threshold Potassium Contracture Tension Development With Voltage Clamp Calcium Indicators Calcium‐Induced Calcium Release Depolarization‐Induced Calcium Release Membrane Potential Changes at SR Level Pharmacological and Experimental Modifications of ECC Effect of Extracellular Calcium Effect of Hypertonic Solutions Transverse‐Tubule Disrupture (Glycerol Treatment) Effects of Anions Effects of Cations Drugs That Activate or Potentiate Contraction Drugs That Depress Contraction Other Treatment

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Contraction in a muscle with negligible sarcoplasmic reticulum: The longitudinal retractor of the sea cucumber Isostichopus badionotus (Selenka), holothuria aspidochirota

et al. 1978

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The longitudinal retractor muscles of the body wall of the sea cucumber Isostichopus badionotus have small cells joined in small bundles by extensive areas of tight surface contact between the cells and on projections a t the center of the bundles. The cells have only a few small mitochondria and negligible sarcoplasmic reticulum. It might be expected that such cells would be poor in intracellular storage sites for calcium for excitation-contraction coupling. However, we have found that it requires up to ten hours incubation of the isolated muscles in calcium-free solutions of chelating agents to abolish contractility in the calcium-free solutions. After that, contraction is directly calcium dependent. Contractility was assessed by measuring either force or shortening during potassium depolarization across a sucrose gap. Caffeine induces contraction even in calcium-free solutions. Thus the physiological evidence indicates that there are internal storage sites for calcium, even though there is scarcely any sarcoplasmic reticulum. On morphological grounds we suggest that there are also superficial sarcolemmic storage sites for calcium. This is suggested by the great increase in sarcolemmic area provided by extraordinary extensions of each cell into the lumen of the bundle.The common large sea cucumber of Bermuda, Zsostichopus badionotus (Selenka) , moves extremely slowly with accompanying marked changes in length. The body wall is rigid and firm, and yet deforms remarkably in response to maintained stress or during locomotion. These features of the activity of the entire animal are mirrored in certain well-known physiological peculiarities of the longitudinal retractor muscles of the body wall, which are extremely slow (Levin and Wyman, '2'7) and can contract to a small fraction of the resting length (Galambos, '41) as can an entire individual Zsostichopus badionotus.One of the more striking pecularities of the isolated longitudinal retractor is that it will stretch "indefinitely" when subjected to a slight stretching force. Van Weel ('55) recorded the effect of gradual stretching under a small load, on the longitudinal retractor muscles from six species of holothurians, includingstichopus tropicdis. The results show that the muscle offers considerable "elastic" resistance to the sudden application of a heavier weight, although maintained application of a lesser weight induces continued "viscous" stretching. Van Weel stretched a longitudinal retractor for a very long time with a moderate load and found that the muscle increased to about three times its normal length, before it became thin enough to snap in the middle "as a 'thread' of plastic -material which is pulled out snaps." In reporting the work-speed curve for the longitudinal muscle of Holothuria nigra, which also slips in length under tension, Levin and Wyman ('27) commented that the muscle was so fragile that it "frequently gave

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The effect of caffeine and tetracaine on the time course of potassium contractures of single muscle fibres.

Cited by 71 publications

References 25 publications

Effects of external calcium reduction on biphasic potassium contractures and action of divalent cations on the calcium reduction in frog single twitch muscle fibers.

Effects of external calcium reduction on biphasic potassium contractures and action of divalent cations on the calcium reduction in frog single twitch muscle fibers.

Pharmacological Investigations of Excitation‐Contraction Coupling

Contraction in a muscle with negligible sarcoplasmic reticulum: The longitudinal retractor of the sea cucumber Isostichopus badionotus (Selenka), holothuria aspidochirota

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