TY - JOUR
T1 - Both short intense and prolonged moderate in vitro stimulation reduce the mRNA expression of calcium-regulatory proteins in rat skeletal muscle
AU - Mänttäri, Satu
AU - Ørtenblad, Niels
AU - Madsen, Klavs
AU - Pilegaard, Henriette
PY - 2013/1
Y1 - 2013/1
N2 - Sarcoplasmic and t-tubule membrane proteins regulating sarcoplasmic Ca 2+ concentration exhibit fibre-type-dependent isoform expression, and play central roles in muscle contraction and relaxation. The purpose of this study was to evaluate the effects of in vitro electrical stimulation on the mRNA expression of components involved in Ca2+ regulation in oxidative and glycolytic skeletal muscle. The mRNA level of Ca2+-ATPase (SERCA1, 2), calsequestrin (CASQ1, 2), ryanodine receptor (RyR1), and dihydropyridine receptor (Cacna1) was assessed in rat extensor digitorum longus (EDL) and soleus (SOL) muscles at 4 h of recovery following in vitro stimulations (either short intensive (SHO) 60 Hz, 5 min, or prolonged moderate (PRO) 20 Hz, 40 min). Stimulation induced acute regulation of the mRNA level of Ca2+-regulating proteins in a manner that does not follow typical fibre-type-specific transitions. In general, stimulation decreased mRNA content of all proteins studied. Most prominent down-regulation was observed for Cacna1 (26 and 32 % after SHO and PRO, respectively, in SOL; 19 % after SHO in EDL). SERCA1, SERCA2, CASQ1, CASQ2, and RyR1 mRNA content also decreased significantly in both muscles relative to resting control. Of notice is that hexokinase II mRNA content was increased in EDL and unchanged in SOL underlining the specificity of the down-regulation of mRNA of Ca2+ regulatory proteins. The results demonstrate contraction-induced down-regulation of mRNAs for the main components of Ca2+-regulating system in skeletal muscle. The down-regulation of both isoforms of SERCA and CASQ after a single electrical stimulation session suggests that adaptations to repeated stimulation involve further regulatory mechanisms in addition to acute mRNA responses.
AB - Sarcoplasmic and t-tubule membrane proteins regulating sarcoplasmic Ca 2+ concentration exhibit fibre-type-dependent isoform expression, and play central roles in muscle contraction and relaxation. The purpose of this study was to evaluate the effects of in vitro electrical stimulation on the mRNA expression of components involved in Ca2+ regulation in oxidative and glycolytic skeletal muscle. The mRNA level of Ca2+-ATPase (SERCA1, 2), calsequestrin (CASQ1, 2), ryanodine receptor (RyR1), and dihydropyridine receptor (Cacna1) was assessed in rat extensor digitorum longus (EDL) and soleus (SOL) muscles at 4 h of recovery following in vitro stimulations (either short intensive (SHO) 60 Hz, 5 min, or prolonged moderate (PRO) 20 Hz, 40 min). Stimulation induced acute regulation of the mRNA level of Ca2+-regulating proteins in a manner that does not follow typical fibre-type-specific transitions. In general, stimulation decreased mRNA content of all proteins studied. Most prominent down-regulation was observed for Cacna1 (26 and 32 % after SHO and PRO, respectively, in SOL; 19 % after SHO in EDL). SERCA1, SERCA2, CASQ1, CASQ2, and RyR1 mRNA content also decreased significantly in both muscles relative to resting control. Of notice is that hexokinase II mRNA content was increased in EDL and unchanged in SOL underlining the specificity of the down-regulation of mRNA of Ca2+ regulatory proteins. The results demonstrate contraction-induced down-regulation of mRNAs for the main components of Ca2+-regulating system in skeletal muscle. The down-regulation of both isoforms of SERCA and CASQ after a single electrical stimulation session suggests that adaptations to repeated stimulation involve further regulatory mechanisms in addition to acute mRNA responses.
U2 - 10.1007/s11010-012-1486-5
DO - 10.1007/s11010-012-1486-5
M3 - Journal article
C2 - 23111891
SN - 0300-8177
VL - 373
SP - 171
EP - 178
JO - Molecular and Cellular Biochemistry
JF - Molecular and Cellular Biochemistry
IS - 1-2
ER -