Click on image to view larger version.
Figure 2 Percent change in mean luminal diameter of the left anterior descending artery (LAD) coronary artery from baseline, in response to maximal intracoronary acetylcholine infusion (10–4 mol/liter). *p < 0.01 versus morning control; 
p < 0.01 versus afternoon control; 
p < 0.05, response in GTN group versus non-GTN group. 
= Nitroglycerin group. 
= Nonnitroglycerin group.