Effect of taurine on sarcoplasmic reticulum function and force in skinned fast-twitch skeletal muscle fibres of the rat.
We examined the effect of taurine on depolarisation-induced force responses and sarcoplasmic reticulum (SR) function in mechanically skinned skeletal muscle fibres from the extensor digitorum longus (EDL) of the rat. Taurine (20 mM) produced a small but significant (P < 0.01) decrease in the sensitivity of the contractile apparatus to Ca(2+) (increase in the [Ca(2+)] corresponding to 50 % of maximum force of about 7 %; n = 10) and in maximum force (92.0 +/- 1.0 % of controls) in the skinned fibres. Taurine had no statistically significant effect on the slope of the force-pCa curve. Depolarisation-induced force responses in the skinned fibres were markedly increased in peak value by 20 mM taurine, to 120.8 +/- 5.3 % of control measurements (P = 0.0006, n = 27). Taurine (20 mM) significantly increased the SR Ca(2+) accumulation in the skinned fibres by 34.6 +/- 9.3 % compared to control conditions (measured by comparing the integral of caffeine contractures in fibres previously loaded with Ca(2+) in the absence or presence of taurine; P = 0.0014, n = 10). Taurine (20 mM) also increased both the peak and rate of rise of caffeine-induced force responses in the fibres by 29.2 +/- 9.7 % (P = 0.0298, n = 6) and 27.6 +/- 8.9 % (P = 0.037), respectively, compared with controls. This study shows that taurine is a modulator of contractile function in mammalian skeletal muscle. Taurine may increase the size of depolarisation-induced force responses by augmenting SR Ca(2+) accumulation and release.
Bakker
Anthony J
AJ
Department of Physiology, The University of Western Australia, Nedlands, WA 6907, Australia. abakker@cyllene.uwa.edu.au
Berg
Helen M
HM
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D004594:Electrophysiology; D006652:Histological Techniques; D009119:Muscle Contraction / Q000187:drug effects; D018656:Muscle Fibers, Fast-Twitch / Q000187:drug effects* / Q000502:physiology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012519:Sarcoplasmic Reticulum / Q000187:drug effects* / Q000502:physiology*; D013654:Taurine / Q000494:pharmacology*
D013654:Taurine; D002110:Caffeine; D002118:Calcium