Background— Peroxisome proliferator–activated receptor-γ (PPARγ) agonists are commonly used to treat diabetes, although their PPARγ-dependent effects transcend their role as insulin sensitizers. Thiazolidinediones lower blood pressure (BP) in diabetic patients, whereas results from conventional/tissue-specific PPARγ experimental models suggest an important pleiotropic role for PPARγ in BP control. Little evidence is available on the molecular mechanisms underlying the role of vascular smooth muscle cell–specific PPARγ in basal vascular tone.

Methods and Results— We show that vascular smooth muscle cell–selective deletion of PPARγ impairs vasoactivity with an overall reduction in BP. Aortic contraction in response to norepinephrine is reduced and vasorelaxation is enhanced in response to β-adrenergic receptor (β-AdR) agonists in vitro. Similarly, vascular smooth muscle cell–selective PPARγ knockout mice display a biphasic response to norepinephrine in BP, reversible on administration of β-AdR blocker, and enhanced BP reduction on treatment with β-AdR agonists. Consistent with enhanced β2-AdR responsiveness, we found that the absence of PPARγ in vascular smooth muscle cells increased β2-AdR expression, possibly leading to the hypotensive phenotype during the rest phase.

Conclusion— These data uncovered the β2-AdR as a novel target of PPARγ transcriptional repression in vascular smooth muscle cells and indicate that PPARγ regulation of β2-adrenergic signaling is important in the modulation of BP.