cAMP transfer across MEGJ mediates regulatory effect of Ang2 on hypo-reactivity after hypoxia in vascular smooth muscle cells / 中国病理生理杂志

ABSTRACT

AIM:To observe the cyclic adenosine monophosphate(cAMP)transfer across myoendothelial gap junctions(MEGJ)in the regulatory effect of angiopoietin-2(Ang2)on hyporeactivity after hypoxia in vascular smooth mus-cle cells(VSMCs ).METHODS:The double-sided cell co-culture model of vascular endothelial cells(VECs )and VSMCs was set up.The protein expression of inducible nitric oxide synthase(iNOS)was determined by Western blot.The contraction of VSMCs was detected via the leakage of FITC-labeled bovine serum albumin.Alexa Fluor 488-cAMP was used as the tracer to observe the cAMP transfer across MEGJ from VECs to VSMCs.RESULTS:In cultured VECs and VSMCs alone ,the cAMP concentrations were both significantly increased after exogenous Ang 2 treatment and hypoxia ,and more in VECs than that in VSMCs(P<0.05).In the double-sided cell co-culture model,the difference was weakened,and the increase in cAMP concentration in VSMCs after exogenous Ang 2 treatment and hypoxia was antagonized by connexin 43(Cx43)small interfering RNA(siRNA)(P<0.05).Alexa Fluor 488-cAMP in VECs transfered into VSMCs after exoge-nous Ang2 treatment and hypoxia,which was also antagonized by Cx43 siRNA(P<0.05).The cAMP antagonist inhibited the protein expression of iNOS in the VSMCs and the hyporeactivity of the VSMCs after exogenous Ang 2 treatment and hy-poxia(P<0.05).CONCLUSION:Ang2 may regulate the protein expression of iNOS in VSMCs and the hyporeactivity of VSMCs after hypoxia through the cAMP transfer across MEGJ.