OBJECTIVETo explore the impact of niflumic acid (NFA) on connexin 43 (Cx43) expression in smooth muscle cells of mesenteric small artery from spontaneously hypertensive rats (SHR).

METHODSBlood pressure of Wistar rats and spontaneously hypertensive rats (SHR) was measured by the tail cuff method. Relaxation and contraction of mesenteric small artery from Wistar rat and SHR were evaluated by pressure myograph system under various concentrations of NFA. Protein Cx43 expression on primary cultured mesenteric smooth muscle cells from Wistar rats and SHR was detected in the absence and presence of various NFA concentrations by Western blot.

RESULTSPhenylephrine resulted in mesenteric small arteries contraction [(193 ± 13.5) µm], while NFA (3×10(-4) mol/L) could relax the artery [(275 ± 17.1) µm]. The relaxation response in Wistar rats was significantly stronger than that in SHR (P < 0.05). Cx43 expression of the first level branch and the third branch mesenteric artery of SHR were higher than the corresponding branch vessels of Wistar rats, and the Cx43 expression of the third branches of mesenteric artery was higher than that of the first branch (F = 1 014.43, P < 0.01). Cx43 expression in primary cultured mesenteric smooth muscle cells was significantly downregulated post NFA treatment in a concentration dependent manner.

CONCLUSIONIn the SHR mesenteric small arteries, Cx43 may be involved in smooth muscle cells communication, thereby affecting vascular contraction and relaxation responses.NFA could downregulate the expression of Cx43 in SHR mesenteric artery vascular smooth muscle cells and induce vasodilation.