FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W1999035891> ?p ?o ?g. }

• W1999035891 endingPage "34" @default.
• W1999035891 startingPage "1" @default.
• W1999035891 abstract "1. The effects of graded concentrations of caffeine on the Na efflux were investigated. External application of 10 m M caffeine usually caused a biphasic response, viz. a fall, followed by a rise in the Na efflux. 1 and 5 m M caffeine usually caused stimulation. Only the stimulatory phase of this response depended on the presence of external Ca2+. 2. Internal application of 100 m M caffeine caused a small rise in the Na efflux, the magnitude of which was independent of external Ca2+ and comparable to that obtained with external application of 1 m M caffeine. This action, however, could be greatly augmented by pre-treating the fibre with 5 × 10−5 M ouabain. 3. The rise in Na efflux caused by external application of 10 m M caffeine could be greatly augmented by pre-treating the fibre with 5 × 10−5 M ouabain. The observed stimulatory response was biphasic, more so in the absence of external Ca2+. Restoration of external Ca2+ following the onset of the second stimulatory phase resulted in further rise of the Na efflux. Measurements of the Na efflux during treatment with graded concentrations of ouabain and 10 m M caffeine showed that the rate coefficient for Na efflux varied with the ouabain concentration in the range 10−8-10−4 M. Measurements of the ouabain-insensitive Na efflux before and during treatment with 10 m M caffeine in bathing media containing varying concentrations of Ca, disclosed the existence of two Ca2+-thresholds, one in the 0–2·5 m M range and the other in the 12·5–15 m M range. 4. Comparisons were made between the effects on the Na efflux of 10 m M caffeine followed by external acidification, and external acidification, followed by 10 m M caffeine. The magnitude of the response of the ouabain-insensitive Na efflux to external acidification before treatment with 10 m M caffeine was greater than that found when external acidification followed external application of the alkaloid. It also was considerably greater than that of the response to external application of 10 m M caffeine before external acidification. 5. External application of 10 m M procaine prevented 10 m M caffeine from stimulating the Na efflux, and from inducing contractures. Internal application of 100 m M-EGTA reduced the response of the Na efflux to 10 m M caffeine, and also prevented the fibre from contracting. External application of 10−4 M diphenylhydantoin reduced the response of the Na efflux to 10 m M caffeine but failed to prevent the development of contractures. 6. Internal application of 0·05 M-cGMP, cAMP or its dibutyryl derivative caused a large rise in the Na efflux. The magnitude of the effects observed in ouabain-poisoned fibres was often greater than that in unpoisoned fibres. Internal application of 2·5 units/ml. phosphodiesterase beforehand failed to reduce the magnitude of the stimulatory response to injected cyclic nucleotides. Injected phosphodiesterase also failed to reduce the response of the Na efflux to 10 m M caffeine. 7. External application of 10 m M caffeine to unpoisoned and ouabain-poisoned fibres caused a fall of approximately 10 mV in the membrane potential. In unpoisoned fibres this effect was transitory. The response of the membrane potential to internal application of graded concentrations of CaCl2 was biphasic. When low concentrations of CaCl2 were used the membrane potential underwent a small rise but when high concentrations were used the opposite was found. These results could not be repeated with graded concentrations of MgCl2. 8. The effects of graded concentrations of caffeine on tension development were also studied. Strong contractures were observed with caffeine concentrations as low as 4 m M, while peak tetanus tension was usually exceeded with 7–8 m M concentrations. The tension—external Ca2+ curve was sigmoidal in shape. 9. Electron microscopic studies showed that 10 m M caffeine in ASW caused little or no distension and disorganization of cisternal fine structure. Such structural changes, however, were far more pronounced in fibres suspended in Ca2+-free ASW and then treated with 10 m M caffeine in Ca2+-free ASW. Fibres soaked in Ca2+-free ASW had ruptured mitochondria and mitoplasts, whereas those additionally treated with 10 m M caffeine had relatively intact mitochondria. 10. The main conclusions drawn from this work are: (i) that caffeine stimulates the ouabain-insensitive Na efflux (and inhibits the transport enzyme) by raising the internal free Ca2+ concentration; (ii) that in the presence of inhibition of the transport enzyme, the magnitude of the stimulatory response to 10 m M caffeine depends not only on the external Ca2+ concentration but mainly on the residual level of activity of the transport enzyme; (iii) that the Ca2+-sensitive and CO2-sensitive components of the ouabain-insensitive Na efflux, though not the same, may overlap at the level of the plasma membrane or share a common metabolic step away from the membrane; (iv) that cyclic nucleotides participate in the control of the magnitude of the ouabain-insensitive Na efflux, and that the phosphodiesterase system under the present experimental conditions does not seem to be involved in the mechanism underlying the stimulatory action of caffeine; (v) that the membrane potential changes caused by caffeine fail to explain the stimulatory response of the Na efflux, as well as contracture of these fibres; (vi) that the contractile machinery in these fibres is considerably more sensitive to caffeine than that in vertebrate muscle and the muscles of other arthropods, and (vii) that the Ca2+ released by the sarcoplasmic reticulum which leads to a biphasic response of the Na efflux is the result of cisternal disorganization caused by caffeine." @default.
• W1999035891 created "2016-06-24" @default.
• W1999035891 creator A5002595395 @default.
• W1999035891 creator A5022310246 @default.
• W1999035891 creator A5036351425 @default.
• W1999035891 creator A5087976701 @default.
• W1999035891 date "1974-10-01" @default.
• W1999035891 modified "2023-10-14" @default.
• W1999035891 title "The effects of caffeine on sodium transport, membrane potential, mechanical tension and ultrastructure in barnacle muscle fibres" @default.
• W1999035891 cites W1567637403 @default.
• W1999035891 cites W1641717686 @default.
• W1999035891 cites W1874138979 @default.
• W1999035891 cites W1966294002 @default.
• W1999035891 cites W1970311357 @default.
• W1999035891 cites W1973995482 @default.
• W1999035891 cites W1987315602 @default.
• W1999035891 cites W1988692398 @default.
• W1999035891 cites W1996795798 @default.
• W1999035891 cites W2002238526 @default.
• W1999035891 cites W2013019312 @default.
• W1999035891 cites W2015556821 @default.
• W1999035891 cites W2018323396 @default.
• W1999035891 cites W2021661801 @default.
• W1999035891 cites W2029845383 @default.
• W1999035891 cites W2031490162 @default.
• W1999035891 cites W2042216906 @default.
• W1999035891 cites W2053955141 @default.
• W1999035891 cites W2071804256 @default.
• W1999035891 cites W2093831431 @default.
• W1999035891 cites W2094693858 @default.
• W1999035891 cites W2107387783 @default.
• W1999035891 cites W2116520996 @default.
• W1999035891 cites W2128903096 @default.
• W1999035891 cites W2131463554 @default.
• W1999035891 cites W2144102948 @default.
• W1999035891 cites W2147662621 @default.
• W1999035891 cites W2160652522 @default.
• W1999035891 cites W2172042059 @default.
• W1999035891 cites W2230924357 @default.
• W1999035891 cites W2337742065 @default.
• W1999035891 cites W2417378968 @default.
• W1999035891 cites W4245428601 @default.
• W1999035891 cites W4298038538 @default.
• W1999035891 doi "https://doi.org/10.1113/jphysiol.1974.sp010691" @default.
• W1999035891 hasPubMedCentralId "https://www.ncbi.nlm.nih.gov/pmc/articles/1330597" @default.
• W1999035891 hasPubMedId "https://pubmed.ncbi.nlm.nih.gov/4373569" @default.
• W1999035891 hasPublicationYear "1974" @default.
• W1999035891 type Work @default.
• W1999035891 sameAs 1999035891 @default.
• W1999035891 citedByCount "37" @default.
• W1999035891 crossrefType "journal-article" @default.
• W1999035891 hasAuthorship W1999035891A5002595395 @default.
• W1999035891 hasAuthorship W1999035891A5022310246 @default.
• W1999035891 hasAuthorship W1999035891A5036351425 @default.
• W1999035891 hasAuthorship W1999035891A5087976701 @default.
• W1999035891 hasBestOaLocation W19990358911 @default.
• W1999035891 hasConcept C12554922 @default.
• W1999035891 hasConcept C134018914 @default.
• W1999035891 hasConcept C178790620 @default.
• W1999035891 hasConcept C185592680 @default.
• W1999035891 hasConcept C200082930 @default.
• W1999035891 hasConcept C24998067 @default.
• W1999035891 hasConcept C2778500429 @default.
• W1999035891 hasConcept C2779133857 @default.
• W1999035891 hasConcept C537181965 @default.
• W1999035891 hasConcept C55493867 @default.
• W1999035891 hasConcept C86803240 @default.
• W1999035891 hasConceptScore W1999035891C12554922 @default.
• W1999035891 hasConceptScore W1999035891C134018914 @default.
• W1999035891 hasConceptScore W1999035891C178790620 @default.
• W1999035891 hasConceptScore W1999035891C185592680 @default.
• W1999035891 hasConceptScore W1999035891C200082930 @default.
• W1999035891 hasConceptScore W1999035891C24998067 @default.
• W1999035891 hasConceptScore W1999035891C2778500429 @default.
• W1999035891 hasConceptScore W1999035891C2779133857 @default.
• W1999035891 hasConceptScore W1999035891C537181965 @default.
• W1999035891 hasConceptScore W1999035891C55493867 @default.
• W1999035891 hasConceptScore W1999035891C86803240 @default.
• W1999035891 hasIssue "1" @default.
• W1999035891 hasLocation W19990358911 @default.
• W1999035891 hasLocation W19990358912 @default.
• W1999035891 hasLocation W19990358913 @default.
• W1999035891 hasOpenAccess W1999035891 @default.
• W1999035891 hasPrimaryLocation W19990358911 @default.
• W1999035891 hasRelatedWork W1976959646 @default.
• W1999035891 hasRelatedWork W1986568396 @default.
• W1999035891 hasRelatedWork W1999035891 @default.
• W1999035891 hasRelatedWork W2009659059 @default.
• W1999035891 hasRelatedWork W2014206408 @default.
• W1999035891 hasRelatedWork W2025949212 @default.
• W1999035891 hasRelatedWork W2051447067 @default.
• W1999035891 hasRelatedWork W2091746893 @default.
• W1999035891 hasRelatedWork W2091893505 @default.
• W1999035891 hasRelatedWork W2165133705 @default.
• W1999035891 hasVolume "242" @default.
• W1999035891 isParatext "false" @default.
• W1999035891 isRetracted "false" @default.
• W1999035891 magId "1999035891" @default.

• next