Chronic inflammation promotes the development of hypertension and is associated with increased T?cell infiltration and cytokine production in impaired organs. Gap junction protein connexin?43?(Cx43), is ubiquitously expressed in immune cells and plays an important role in T?cell proliferation and activation, and cytokine production. However, the correlation between Cx43 in T?cells and the hypertensive inflammatory response remains unknown. Thus, in this study, we wished to examine this correlation. First, our results revealed that hypertension caused significant thickening of the vascular wall, inflammatory cell infiltration into part of the renal interstitium and glomerular atrophy, and it increased the tubular damage scores in the kidneys of spontaneously hypertensive rats?(SHRs). Moreover, the SHRs exhibited stenosis in the central artery wall ofthe spleen with increased serum levels of interleukin?(IL)-2 and IL-6 compared with normotensive Wistar-Kyoto?(WKY) rats. The spleens of the SHRs exhibited a significantly decreased percentage of CD4+CD25+?(Treg) T?cells. However, the percentages of CD3+, CD4+ and CD8+ T?cell and the levels of CD4+Cx43 and CD8+Cx43 did not differ significantly between the SHRs and WKY rats. In cultured lymphocytes from the SHRs and WKY rats, low percentages of Treg cells and reduced cytokine?(IL-2 and IL-6) mRNA expression levels were observed in the lymphocytes obtained from the SHRs and WKY rats treated with the connexin blocker, Gap27, or concanavalin?A?(ConA) plus Gap27. The effects of ConA and Gap27 differed between the SHRs and WKY rats. On the whole, our findings demonstrate that the splenic Treg cell-mediated suppression in SHRs may be involved in hypertensive inflammatory responses. Cx43 in the gap junctional channel may regulate lymphocyte activation and inflammatory cytokine production.