Fig. 5.
Peripheral administration of irisin reduced blood pressure. Blood pressure and cardiac contractility were measured in control (SD) or spontaneously hypertensive (SHR) rats. IgG Fc peptide and r-irisin were delivered via femoral vein injection. (a) Control IgG Fc peptide did not change blood pressure; r-irisin (2–4 μg) significantly reduced blood pressure (upper panel). Neither IgG Fc nor r-irisin changed cardiac contractility (lower panel). (b) r-irisin(2–8 μg) significantly reduced blood pressure in SHR. (c) Vasoactivity of mesenteric artery rings with or without endothelium was measured. The rings were pre-constricted with 10−6 M phenylephrine (PE). When the contraction of rings reached plateau level, relaxation in response to r-irisin was assayed in the presence or absence of 10 μM glibenclamide (a KATP channel blocker)