Abstract
Adjuvant arthritis (AA) is a condition that involves systemic oxidative stress. Unexpectedly, it was found that sarcoplasmic reticulum Ca2 +-ATPase (SERCA) activity was elevated in muscles of rats with AA compared to controls, suggesting possible conformational changes in the enzyme. There was no alteration in the nucleotide binding site but rather in the transmembrane domain according to the tryptophan polar/non-polar fluorescence ratio. Higher relative expression of SERCA, higher content of nitrotyrosine but no increase in phospholipid oxidation in AA SR was found. In vitro treatments of SR with HOCl showed that in AA animals SERCA activity was more susceptible to oxidative stress, but SR phospholipids were more resistant and SERCA could also be activated by phosphatidic acid. It was concluded that increased SERCA activity in AA was due to increased levels of SERCA protein and structural changes to the protein, probably induced by direct and specific oxidation involving reactive nitrogen species.
Abbreviations | ||
AA | = | adjuvant arthritis |
a.u. | = | arbitrary units |
BSA | = | bovine serum albumin |
Cai | = | intracellular calcium |
= | free calcium ions | |
Co | = | control |
DNPH | = | dinitrophenylehydrazine |
FITC | = | fluorescein-5-isothiocyanate |
GSH | = | reduced glutathione |
I | = | fluorescence intensity |
IC50 | = | half maximal inhibitory concentration |
LC-MS | = | liquid chromatography-mass spectrometry |
NO | = | nitric oxide |
pATP | = | negative logarithm of the concentration of ATP |
PA | = | phosphatidic acid |
PCs | = | phosphatidylcholines |
PEs | = | phosphatidylethanolamines |
PLs | = | phospholipids |
pCafree | = | negative logarithm of the concentration of free Ca2 + ions |
RA | = | rheumatoid arthritis |
RFUs | = | relative fluorescence units |
RNS | = | reactive nitrogen species |
ROS | = | reactive oxygen species |
SERCA | = | sarcoplasmic/endoplasmic reticulum Ca2 +-ATPase |
SR | = | sarcoplasmic reticulum |
TBARS | = | thiobarbituric acid reactive substances |
Abbreviations | ||
AA | = | adjuvant arthritis |
a.u. | = | arbitrary units |
BSA | = | bovine serum albumin |
Cai | = | intracellular calcium |
= | free calcium ions | |
Co | = | control |
DNPH | = | dinitrophenylehydrazine |
FITC | = | fluorescein-5-isothiocyanate |
GSH | = | reduced glutathione |
I | = | fluorescence intensity |
IC50 | = | half maximal inhibitory concentration |
LC-MS | = | liquid chromatography-mass spectrometry |
NO | = | nitric oxide |
pATP | = | negative logarithm of the concentration of ATP |
PA | = | phosphatidic acid |
PCs | = | phosphatidylcholines |
PEs | = | phosphatidylethanolamines |
PLs | = | phospholipids |
pCafree | = | negative logarithm of the concentration of free Ca2 + ions |
RA | = | rheumatoid arthritis |
RFUs | = | relative fluorescence units |
RNS | = | reactive nitrogen species |
ROS | = | reactive oxygen species |
SERCA | = | sarcoplasmic/endoplasmic reticulum Ca2 +-ATPase |
SR | = | sarcoplasmic reticulum |
TBARS | = | thiobarbituric acid reactive substances |