Abstract:Aim To explore the modification of inositol 1,4,5-trisphosphate receptor type Ⅰ(IP3RⅠ) expression by calcineurin in calcification of vascular smooth muscle cells. Methods Rat aortic vascular smooth muscle cells after subculture were randomly divided into control group,calcification group and cyclosporine A(CsA) group.Rat aortic vascular smooth muscle cell calcification model was constructed by NaH2PO4.Expression of IP3RⅠand calcineurin was determined by RT-PCR and Western blot methods.Alkaline phosphatase(ALP) Activity and Ca2+ concentration were determined by colorimetric method.CaN activity was determined by ELISA. Results Expressions of IP3RⅠand CaNB mRNA and protein increased in calcification group compared with control group(P<0.01).Expressions of IP3RⅠand CaNB mRNA and protein decreased in CsA group compared with calcification group(P<0.01).Ca2+ concentration and CaN and ALP activities of rat aortic smooth muscle cells increased in calcification group compared with control group(P<0.01).ALP activity and Ca2+ concentration increased in CsA group compared with calcification group(P<0.05 or P<0.01).CaN activity decreased in CsA group compared with calcification group(P<0.01). Conclusions CaN can enhance the expression of IP3RⅠmRNA and protein in cell calcification.

Abstract:Aim To research the cross regulation of cGMP-dependent protein kinase(PKG) and calcineurin(CaN) in vascular smooth muscle cells(SMC) proliferation. Methods Primary vascular SMC from rat aorta were used as the experimental model.Expression of CaN and PKG was assayed using immunoblotting.Cell growth was determined by MTT assay. Results The results showed that phenylephrine(PE)-induced expression and activity of CaN protein was reduced by S-nitroso-N-acetylpenicillamine(SNAP) and Sp-8-pCPT-cGMP,but increased by Rp-8-pCPT-cGMP.The OD ratio of PKG Iα mRNA expression in 0.5 mg/L cyclosporin A(CsA) group resembled control group while in 5 mg/L CsA group was significantly higher than control group(p<0.01).Although the result of 5 mg/L CsA+10 μmol/L PE group was lower than 5 mg/L CsA group(the expression of mRNA decreased 32.2%;the production of PKG Iα protein decreased 36.7%,p<0.01),but still higher than control group obviously(p<0.05).In SMC pretreated with CsA,absorbance of cells stimulated by PE decreased by 36.67%,but it could not be further altered by the additional treatment of SNAP,Sp-8-pCPT-cGMP and Rp-8-pCPT-cGMP. Conclusion PKG and CaN can cross-regulate in vascular smooth mucle cells proliferation.

Abstract:Aim To observe the effect of cyclosporin A( a inhibitor of calcineurin). On cardioprotection induced by ischemia preconditioning (IPC) and explore the role of calcineurin (CaN) signal pathway in IPC. Methods The model of ischemia /reperfusion (I/R) was produced in isolated rat heart. The cardic functions and the activity of myocardium calcineurin were mersured. Results It was found that IPC apparently attenuated the inhibition of cardic function induced by I/R. Compared with I/R group, in IPC group coronary perfusion flow(CPF),+LVdp/dt max and -LVdp/dt max decreased by 39%(P<0.01),33%(P<0.01) and 52%(P<0.01) respectively. Myocardial calcium content decreased by 21%(P<0.01). However CsA, the inhibitor of CaN, can conteract the cardioprotection effect of IPC. In addition, the activity of cardiac calcineurin was activated by cardiac I/R, compared with control group, the activity of CaN increased by 1.9 folds; ischemia preconditoning alone activated the activity of cardiac calcineurin and increased by 2.3 folds (P<0.01) compared with control group. Before ischemia preconditioning administration of CsA completely blocked the activation of calcineurin stimulated by IPC. Compared with IPC group, its activity decreased by 75%(P<0.01). Conclusion The results suggest that IPC-induced cardioprotective efffects are mediated by calcineurin pathway.