Effect of saponin treatment on the sarcoplasmic reticulum of rat, cane toad and crustacean (yabby) skeletal muscle

Launikonis, Bradley S. and Stephenson, D. George (1997) Effect of saponin treatment on the sarcoplasmic reticulum of rat, cane toad and crustacean (yabby) skeletal muscle. Journal of Physiology, 504 2: 425-437. doi:10.1111/j.1469-7793.1997.425be.x


Author Launikonis, Bradley S.
Stephenson, D. George
Title Effect of saponin treatment on the sarcoplasmic reticulum of rat, cane toad and crustacean (yabby) skeletal muscle
Journal name Journal of Physiology   Check publisher's open access policy
ISSN 0022-3751
Publication date 1997-10-01
Sub-type Article (original research)
DOI 10.1111/j.1469-7793.1997.425be.x
Volume 504
Issue 2
Start page 425
End page 437
Total pages 13
Place of publication Oxford
Publisher Blackwell for the Physiological Society
Language eng
Abstract 1. Mechanically skinned fibres from skeletal muscles of the rat, toad and yabby were used to investigate the effect of saponin treatment on sarcoplasmic reticulum (SR) Ca2+ loading properties. The SR was loaded submaximally under control conditions before and after treatment with saponin and SR Ca2+ was released with caffeine. 2. Treatment with 10 mu g ml(-1) saponin greatly reduced the SR Ca2+ loading ability of skinned fibres from the extensor digitorum longus muscle of the rat with a rate constant of 0.24 min(-1). Saponin concentrations up to 150 mu g ml(-1) and increased exposure time up to 30 min did not further reduce the SR Ca2+ loading ability of the SR, which indicates that the inhibitory action of 10-150 mu g ml(-1) saponin is not dose dependent. The effect of saponin was also not dependent on the state of polarization of the transverse-tubular system. 3. Treatment with saponin at concentrations up to 100 mu g ml(-1) for 30 min did not affect the Ca2+ loading ability of SR in skinned skeletal muscle fibres from the twitch portion of the toad iliofibularis muscle but SR Ca2+ loading ability decreased markedly with a time constant of 0.22 min(-1) in the presence of 150 mu g ml(-1) saponin. 4. The saponin dependent increase in permeability could be reversed in both rat and toad fibres by short treatment with 6 mu M Ruthenium Red, a potent SR Ca2+ channel blocker, suggesting that saponin does affect the SR Ca2+ channel properties in mammalian and anuran skeletal muscle. 5. Treatment of skinned fibres of long sarcomere length (> 6 mu m) from the claw muscle of the yabby (a freshwater decapod crustacean) with 10 mu g ml(-1) saponin for 30 min abolished the ability of the SR to load Ca2+, indicating that saponin affects differently the SR from skeletal muscles of mammals, anurans and crustaceans. 6. is concluded that at relatively low concentrations, saponin causes inhibition of the skeletal SR Ca2+ loading ability in a species dependent manner, probably by increasing the Ca2+ loss through SR Ca2+ release channels.
Keyword Physiology
Calcium-release
Ca-2+ Release
Fast-twitch
Fibers
Contraction
Excitation
Mg2+
Stimulation
Ryanodine
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biomedical Sciences Publications
 
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Created: Tue, 14 Aug 2007, 03:01:34 EST