The Differences Gap Junction In The Expression And Function Of Cerebral Artery In Spontaneously Hypertensive And Normotensive Rat

Objective: To investigate the change of connexins(Cxs) in brain artery(BA) of spontaneously hypertensive rats(SHR) and normotensive Wistar rats.Methods: whole cell patch clamp investigate the electrophysiological properties of gap junction in BA between the SHR and Wistar rats. RT-PCR and Western blot were used to investigate the difference express of gap junction in BA between the SHR and Wistar rats. Application of transmission electron microscopy to observation the morphological change of gap junction between smooth muscle cells in BA.Results:(1) Whole cell patch clamp technique found the membrane capacitance and conductivity to artery smooth muscle cell in brain of SHR were obviously higher than normal Wistar rats(P<0.05). Indicate that gap junctional intercellular communication capacity enhancement between cerebral artery smooth muscle cell of SHR.(2) RT-PCR detected the expression of Cx37、Cx40、Cx43 and Cx45 m RNA to SHR and normotensive Wistar rat in brain artery. Compared with that of the normotensive rats, the level of Cx37 and Cx40 m RNA expression in MA from SHR was decreased by RT-PCR technology(P<0.01); Cx45 m RNA expression in MA from SHR was significantly increased compared with the normotensive rats(P<0.01), but no change in the expression of Cx43 m RNA(P>0.05).(3) Western blot detected the protein expression of connexin in brain artery to SHR and normotensive Wistar rat. The results show consistent with the transcript levels.Compared with normotensive rats, the protein expression of Cx37 and Cx40 was significantly reduced in brain artery of SHR(P<0.05); The protein expression of Cx43 in brain artery have no statistical difference between two kinds of rat(P>0.05), but the phosphorylation level of Cx43 was significantly higher than normotensive rats(P<0.01); The expression of Cx45 in brain artery of SHR was significantly higher than normotensive rats(P<0.01).(4) The number of gap junctions between smooth muscle cells was significantly higher to SHR in brain artery than normotensive rats by transmission electron microscopy.Conclusion: Through the experiment results indicate the gap junction communication between SHR brain artery smooth muscle cells is enhancement. Gap junction may by lowering the Cx37 and Cx40 on the vascular endothelial cells and elevating the expression of Cx45 to regulation of smooth muscle cells in the brain artery diastolic activity that will affect hypertension development and progression.