HYPERTENSION INCREASES CONNEXIN43 IN A TISSUE-SPECIFIC MANNER

Background Connexin43 (Cx43), a membrane protein involved in the contr ol of cell-to-cell communication, is thought to play a role in the con tractility of the vascular wall and in the electrical coupling of card iac myocytes. The aim of this study was to investigate the effects of experimental hypertension on Cx43 expression in rat aorta and heart. M ethods and Results Rats were made hypertensive after one renal artery was clipped (two kidney, one-clip renal model) or after the administra tion of deoxycorticosterone and salt (DOCA-salt model). After 4 weeks, all rats showed a similar increase in intra-arterial mean blood press ure and in the thickness of both the aortic wall and the heart. Northe rn blot analysis of aorta mRNA and immunolabeling for Cx43 showed that hypertensive rats expressed twice as much Cx43 in aorta as the contro l animals. In contrast, no difference in Cx43 mRNA or in the immunolab eled protein was observed in heart. Conclusions The results show that rats exhibiting a similar degree of blood pressure elevation, as the r esult of different mechanisms, feature a comparable increase in Cx43 g ene expression, which was observed in the aortic but not in the cardia c muscle. These data suggest that localized mechanical forces induced by hypertension are major tissue-specific regulators of Cx43 expressio n.