Effects of pioglitazone and rosiglitazone on vascular function of mesenteric resistance arteries in rat genetic hypertension

Abstract

Glitazones exhibit beneficial effects in the vascular system, both on large vessels and at a microcirculatory level. We previously reported the effects of glitazones in the aorta of spontaneously hypertensive rats (SHR). We focus now on the acute and long-term actions of these drugs on mesenteric resistance arteries of the SHR. Incubation with pioglitazone or rosiglitazone (10⁻⁵ mol/l) improved endothelium-dependent relaxations to acetylcholine and the endothelial modulation of phenylephrine contractions. Acetylcholine relaxations that were abolished by N(G)-nitro-L-arginine methylester were partly recovered by the glitazones, but no effects of these drugs were observed in the presence of indomethacin or indomethacin + L-NAME. Glitazones did not change the contractions to U46619 or the endothelium-independent relaxation to sodium nitroprusside. Three-week oral pioglitazone or rosiglitazone treatment (3 and 10 mg/kg/day, respectively) confirmed the acute experiments. Thus, in microvessels, glitazones improve endothelial function in such a way that they do not alter endothelial nitric oxide release but reduce the production of vasoconstrictor prostanoids from endothelial cells.