Skip to main content
. Author manuscript; available in PMC: 2013 Jan 26.
Published in final edited form as: Nat Med. 2010 Feb 28;16(3):279–285. doi: 10.1038/nm.2092

Fig. 4. The IDO pathway metabolite Kyn regulates vascular tone.

Fig. 4

(a) Relaxation of porcine coronary arteries in response to addition of Trp. Fresh porcine circumflex arteries with intact or denuded endothelium (EC) were incubated for 20 h at 37 °C in M199 in the absence or presence of 400 ng IFNγ/mL. Arteries were then removed, washed and incubated with 300 μM N-nitro-l-arginine methyl ester and 10 μM indomethacin for 30 min and pre-contracted with U-46619 to 50-60% of maximum force. Relaxation was determined in response to addition of Trp (8 mM final concentration). *P<0.05 versus EC-denuded and 1-Me-Trp-treated groups. (b) Contraction of porcine coronary artery in response to U-46619 in control preparations (❍) and in preparations pre-treated with 6 mM Kyn for 1 h (●). *P<0.05 versus control. (c) Relaxation of denuded vessel rings (▲) or rings with intact EC in response to added DMSO (❍, vehicle control) or Kyn (●). *P<0.05 versus control. (d, e) Trp, Kyn or sodium nitroprusside (SNP) was injected into spontaneously hypertensive rats via the femoral vein to give final blood concentrations ranging from 0.15 – 1.5 mM (for Kyn and Trp) and 0.15 – 1.5 μM (SNP), with systolic blood pressure being monitored continuously. We assumed a total blood volume of 17 mL for the 250 g rats used. (d) Typical blood pressure responses elicited by 1.5 mM of either Kyn or Trp, or 1.5 μM SNP. (e) Dose-dependent changes in systolic blood pressure following injection of Kyn (●), Trp (Δ) or SNP (❍). The results show mean±SEM of four (a), six (b, c) or three (e) independent experiments.