Effects of trans‐ versus cis‐resveratrol on adrenergic contractions of the rat tail artery and role of endothelium

Figure 1. Representative chart recordings demonstrating the effects of 26‐µM trans‐resveratrol (resveratrol) and its vehicle on phenylephrine (PE)‐induced contractions of vascular rings from the proximal portion of the rat tail artery with endothelium removal achieved with saponin. Shown is a transient increase in contraction immediately after administration of resveratrol followed by delayed sustained decrease (above). Lack of such effects are shown after administration of vehicle (below). Similar effects were observed among vascular rings with endothelium‐intact. Each PE = 0.5 µM

Figure 2. Effect of endothelium removal on the magnitude of the second PE‐induced contractions observed prior to addition of trans‐resveratrol (resveratrol) or its vehicle. *p < .05 versus Endo‐intact represents a statistically significant difference from two‐factor ANOVA not only when vehicle and resveratrol data are combined, but also when analyzed separately

Figure 3. Effect of endothelium removal on initial (8–9 min) maximal changes in second PE‐induced contractions after addition of trans‐resveratrol (resveratrol) or its vehicle (a) and the time course of such changes as observed from 2 to 20 min (b). Calculated as percent change in magnitude of PE‐induced contractions observed immediately before addition of resveratrol or its vehicle to the magnitude observed later at the various time points. For a, the duration of 8–9 min was calculated from the mean time to peak increases after addition of resveratrol and applied then to the vehicle group in order to calculate its related percent changes. *p < .05 versus vehicle represents a statistically significant difference from two‐factor ANOVA for comparisons between resveratrol and vehicle in both endothelium‐intact and endothelium‐removed rings but not for removal of the endothelium itself. All vascular rings administered resveratrol demonstrated transient increases in PE‐induced contractions

Figure 4. Effect of endothelium removal on final (2 hr) changes in second PE‐induced contractions observed after the addition of trans‐resveratrol (resveratrol) or its vehicle (a) and the time course of such changes as observed from 20 to 130 min (b). Calculated as percent change in magnitude of contractions observed immediately before addition of resveratrol or its vehicle to the magnitude observed later at the various time points. At all times from 40 to 130 min, two‐factor ANOVA revealed an overall statistically significant main factor effect of endothelium removal (p < .05) for both resveratrol‐ and vehicle‐treated rings, but only when analyzed in combination not separately by Bonferroni's mean comparisons *p < .05 versus vehicle represents a statistically significant effect from two‐factor ANOVA for comparisons of resveratrol versus vehicle in both endothelium‐intact and endothelium‐removed rings

Figure 5. Spearman's correlation coefficients (r) relating final (2 hr) changes to initial (8–9 min) changes in PE‐induced contractions following addition of trans‐resveratrol (resveratrol) or its vehicle to arterial rings with endothelium‐intact or endothelium‐removed. Spearman's correlation coefficients were statistically significant after addition of resveratrol to both endothelium‐intact and endothelium‐removed arterial rings but smaller in magnitude after addition of vehicle to all rings and then only significant for endothelium‐intact rings

Figure 6. Initial (6 min) and final (2 hr) changes in PE‐induced contractions after addition of trans‐ and cis‐resveratrol to rat tail arterial rings; calculated as percent change in the magnitude of the PE‐induced contractions observed immediately before such additions. The duration of 6 min was the average time to the initial peak increases after addition of the trans‐resveratrol and was therefore applied then to the cis‐resveratrol group in order to calculate its related percent changes. p < .05 indicates statistically significant differences between the trans‐ versus cis‐resveratrol, at both the 6‐min and the 2‐hr times

Figure 7. The comparative chemical structures of trans‐ and cis‐resveratrol