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Effects of Verapamil and Gadolinium on Caffeine-Induced Contractures and Calcium Fluxes in Frog Slow Skeletal Muscle Fibers


Shabala, Lana and Sanchez-Pastor, E and Trujillo, X and Shabala, SN and Miniz, J and Huerta, M, Effects of Verapamil and Gadolinium on Caffeine-Induced Contractures and Calcium Fluxes in Frog Slow Skeletal Muscle Fibers, Journal of Membrane Biology, 221, (1) pp. 7-13. ISSN 0022-2631 (2008) [Refereed Article]

DOI: doi:10.1007/s00232-007-9079-z


In this work, we tested whether L-type Ca2+ channels are involved in the increase of caffeine-evoked tension in frog slow muscle fibers. Simultaneous net Ca2+ fluxes and changes in muscle tension were measured in the presence of caffeine. Isometric tension was recorded by a mechanoelectrical transducer, and net fluxes of Ca2+ were measured noninvasively using ion-selective vibrating microelectrodes. We show that the timing of changes in net fluxes and muscle tension coincided, suggesting interdependence of the two processes. The effects of Ca2+ channel blockers (verapamil and gadolinium) were explored using 6 mm caffeine; both significantly reduced the action of caffeine on tension and on calcium fluxes. Both caffeine-evoked Ca2+ leak and muscle tension were reduced by 75% in the presence of 100 μm GdCl3, which also caused a 92% inhibition of net Ca2+ fluxes in the steady-state condition. Application of 10 μm verapamil to the bath led to 30% and 52% reductions in the Ca2+ leak caused by the presence of caffeine for the peak and steady-state values of net Ca2+ fluxes, respectively. Verapamil (10 μm) caused a 30% reduction in the maximum values of caffeine-evoked muscle tension. Gd3+ was a more potent inhibitor than verapamil. In conclusion, L-type Ca2+ channels appear to play the initial role of trigger in the rather complex mechanism of slow fiber contraction, the latter process being mediated by both positive Ca2+-induced Ca2+ release and negative (Ca2+ removal from cytosol) feedback loops. © 2007 Springer Science+Business Media, LLC.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Microbiology
Research Field:Microbial ecology
Objective Division:Health
Objective Group:Public health (excl. specific population health)
Objective Field:Food safety
UTAS Author:Shabala, Lana (Associate Professor Lana Shabala)
UTAS Author:Shabala, SN (Professor Sergey Shabala)
ID Code:49995
Year Published:2008
Web of Science® Times Cited:4
Deposited By:Agricultural Science
Deposited On:2008-04-09
Last Modified:2014-12-17

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