Characterization of Endothelium-Dependent Relaxation in the Saphenous Artery and Its Caudal Branches in Young and Old Adult Sprague Dawley Rats

Figure 1. Anatomical representation of hind limb arteries in male Sprague Dawley rat. The femoral artery (orange) is identified as the artery prior to bifurcation into popliteal and epigastric arteries. The saphenous arteries were separated into proximal (green), middle (red), and distal (blue) segments based on distance to the femoral artery. The caudal branch (purple) is one of the bifurcations of the saphenous artery.

Figure 2. The effects of NO synthase inhibitor L-NAME on phenylephrine-induced contractions of (a) femoral, (b) proximal, (c) middle, (d) distal saphenous artery segments, and (e) caudal branches from young Sprague Dawley rats. The results are expressed as mean ± S.E.M of (n) rats. Lines represent best-fit four parameter sigmoidal dose response curves. # p < 0.05, vs. Emax control; ‡ p < 0.05, vs. −logEC50 control by Student’s t-test.

Figure 3. The effects of NO synthase inhibitor L-NAME on U46618-induced contractions of (a) proximal, (b) middle, (c) distal saphenous artery segments, and (d) caudal branches from (circle symbols) young and (square symbols) old Sprague Dawley rats. The results are expressed as mean ± S.E.M of (n) rats. Differences in best-fit curve parameters were compared by 2-way ANOVA, followed by Bonferroni post-hoc test. Lines represent best-fit four parameter sigmoidal dose response curves. # p < 0.05, vs. Emax young + control; ‡ p < 0.05, vs. −log EC50 young + control; § p < 0.05, Emax L-NAME vs. control; ¶ p < 0.05, −log EC50 L-NAME vs. control.

Figure 4. Acetylcholine-induced relaxations of (a) proximal, (b) middle, (c) distal saphenous artery segments, and (d) caudal branches from (circle symbols) young and (square symbols) old Sprague Dawley rats. The results are expressed as mean ± S.E.M of (n) rats. Lines represent best-fit four parameter sigmoidal dose response curves for controls. Differences in best-fit curve parameters for controls were compared by Student’s t-test. # p < 0.05, ## p < 0.01, ### p < 0.001, vs. Emax young; † p < 0.05, vs. nH young. Differences in relaxations in control vs. L-NAME treatment were compared by 2-way ANOVA with Bonferroni post hoc. * p < 0.05, ** p < 0.01, *** p < 0.001, vs. age-matched control.

Figure 5. PAR2-specific agonist-induced relaxations of (a) proximal, (b) middle, (c) distal saphenous artery segments, and (d) caudal branches from (circle symbols) young and (square symbols) old Sprague Dawley rats. The results are expressed as mean ± S.E.M of (n) rats. Solid lines represent best-fit four parameter sigmoidal dose response curves for controls. Differences in best-fit curve parameters for controls were compared by Student’s t-test. ## p < 0.01, vs. Emax young control. Differences in relaxations of control vs. L-NAME treatment were compared by 2way ANOVA with Bonferroni post hoc. * p < 0.05, ** p < 0.01, *** p < 0.001, vs. age-matched control.

Figure 6. Nitroprusside-induced relaxations of proximal, middle, distal saphenous artery segments, and caudal (end) branches from (white and grey bars) young and (black and striped bars) old Sprague Dawley rats. Arteries treated as either controls (white and black bars) or with L-NAME (grey and striped bars). Relaxation % is the reversal of active tension by addition of 1 µM nitroprusside in U46619-precontracted arteries. The results are expressed as mean ± S.E.M (young, n = 3–18; old, n = 3–6). Differences in relaxations of young vs. old were compared by 2way ANOVA with Bonferroni post hoc. *** p < 0.001, vs. treatment-matched artery in young group.