Influence of thioredoxin system on myocardial Ito in rats with diabetic mellitus
LI Xue-yong
ZENG Wei
LIU Gang
ZHENG Ming-qi
TIAN Fu-li
SUN Yi
BU Xue-qin
SUN He-jian
Abstract：Objective To study the influence of thioredoxin system (Trx) on transient outward potassium current (Ito) of left ventricular myocardial cells in rats with diabetic mellitus (DM).Methods DM model was established in rats by using STZ (DM group,n=25), and other rats without using STZ were included in control group (n=20). CardiomyocyteIto was recorded by applying whole-cell patch clamp method, and content of redox-active molecules was detected by using spectrophotometer. The oxidation degree of protein thiols was reviewed by using DTNB method. The myocardial cells from DM rats were cultured in vitro with insulin for observing the changes of Ito before and after culturing, and then the cells were treated with auranofin or 13-cis-retinoic acid (Trx inhibitors) for observing the change ofIto before and after treating.Results There were 22 rats survived in DM group and 20 in control group. Compared with control group, the levels of Trx reductase (TrxR) and glutathione reductase (GR) decreased significantly in DM group [TrxR: (70.3±4.9) mU/mgvs. (147.9±18.2) mU/mg; GR: (34.4±2.4) mU/mg vs. (53.1±1.9) mU/mg,P<0.05], and levels of Trx and glutaredoxin (Grx) increased significantly [Trx: (15.6± 1.8) mU/mgvs. (9.2±1.9) mU/mg; Grx: (36.5±6.1) mU/mgvs. (14.7±1.0) mU/mg,P<0.05]. At the same time, left ventricular myocardial free thiols decreased significantly in DM group compared with control group [(6.1±0.3) nmol/mgvs. (10.2±0.8) nmol/mg, P<0.05]. The density ofIto decreased significantly in DM group compared with control group [(16.8±2.4) pApFvs. (30.6±2.8) pApF,P<0.05], which increased significantly after insulin treating for 4-5 h (31.2±2.1pApF,P<0.05). Auranofin or 13-cis-retinoic acid reduced significantly the density ofIto treated with insulin (P<0.05).Conclusion The decrease of Trx function can induce the significant decrease of density ofIto.
Keywords：Myocardial cellsDiabetis mellitusIto potassium channelPatch clampThioredoxin system
Publication Date：2013-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：4( 645-648 )