Ropivacaine-Induced Contraction Is Attenuated by Both Endothelial Nitric Oxide and Voltage-Dependent Potassium Channels in Isolated Rat Aortae

Figure 4

(a) and (b) The effect of 4-aminopyridine (4-AP), tetraethylammonium (TEA), barium chloride, and glibenclamide on ropivacaine concentration-response curves in endothelium-intact aortae without or with 1×10⁻⁴ M N ^ω-nitro-L-arginine methyl ester (L-NAME). (c) The effect of 4-AP and TEA on phenylephrine concentration-response curves in endothelium-intact aortae. (a) and (b) Data are shown as the mean ± SD and expressed as a percentage of the maximal contraction induced by isotonic 60 mM KCl. N indicates the number of rats from which descending thoracic aortic rings were derived. (a) 100% = 2.38±0.27 g (𝑛=10), 100% = 2.48±0.47 g (𝑛=6), 100% = 2.20±0.22 g (𝑛=6), 100% = 2.32±0.31 g (𝑛=5), and 100% = 2.39±0.31 g (𝑛=5) for untreated endothelium-intact aortae and endothelium-intact aortae treated with 2×10⁻³ M 4-AP, 2×10⁻³ M TEA, 3×10⁻⁵ M barium chloride, and 1×10⁻⁵ M glibenclamide, respectively. (b) 100% = 2.37±0.22 g (𝑛=6), 100% = 2.81±0.37 g (𝑛=6), 100% = 2.71±0.30 g (𝑛=6), and 100% = 2.77±0.14 g (𝑛=6) for untreated endothelium-intact aortae, endothelium-intact aortae pretreated with 1×10⁻⁴ M L-NAME alone, endothelium-intact aortae pretreated with 1×10⁻⁴ M L-NAME plus 2×10⁻³ M 4-AP, and endothelium-intact aortae pretreated with 1×10⁻⁴M L-NAME plus 2×10⁻³ M TEA, respectively. (c) Data are shown as the mean ± SD and expressed as a percentage of the maximal contraction induced by isotonic 60 mM KCl (100% = 2.74±0.32 g (𝑛=5), 100% = 2.77±0.35 g (𝑛=5), and 100% = 2.66±0.38 g (𝑛=5) for untreated endothelium-intact aortae and endothelium-intact aortae treated with 2×10⁻³ M 4-AP and 2×10⁻³ M TEA, resp.). N indicates the number of descending thoracic aortic rings. (a): ^∗𝑃<0.001 versus control. (b) ^∗𝑃<0.001, ^†𝑃<0.01 and ^#𝑃<0.05 versus control. ^§𝑃<0.001 versus 1×10⁻⁴M L-NAME alone. (c) ^∗𝑃<0.001 and ^†𝑃<0.01 versus control.