Sección Departamental de Fisiología Animal, Facultad de Farmacia, Universidad Complutense de Madrid, Plaza Ramón y Cajal s/n, Madrid, Spain.
Eur J Pharmacol. 2010 Sep 1;641(1):61-6. doi: 10.1016/j.ejphar.2010.05.004. Epub 2010 May 21.
This study was designed to determine whether K+ channels play a role in nitric oxide (NO)-dependent acetylcholine relaxation in porcine internal mammary artery (IMA). IMA segments were isolated and mounted in organ baths to record isometric tension. Acetylcholine-elicited vasodilation was abolished by muscarinic receptor blockade with atropine (10(-6)M). Incubation with indomethacin (3 x 10(-6)M), superoxide dismutase (150 U/ml) and bosentan (10(-5)M) did not modify the acetylcholine response ruling out the participation of cyclooxygenase-derivates, reactive oxygen species or endothelin. The relaxation response to acetylcholine was strongly diminished by NO synthase- or soluble guanylyl cyclase-inhibition using L-NOArg (10(-4)M) or ODQ (3 x 10(-6)M), respectively. The vasodilation induced by acetylcholine and a NO donor (NaNO(2)) was reduced when rings were contracted with an enriched K+ solution (30 mM), by voltage-dependent K+ (K(v)) channel blockade with 4-amynopiridine (4-AP; 10(-4)M), by Ca(2+)-activated K+ (K(Ca)) channel blockade with tetraethylammonium (TEA; 10(-3)M), and by apamin (5 x 10(-7)M) plus charybdotoxin (ChTx; 10(-7)M) but not when these were added alone. In contrast, large conductance K(Ca) (BK(Ca)), ATP-sensitive K+ (K(ATP)) and inwardly rectifying K+ (K(ir)) channel blockade with iberiotoxin (IbTx; 10(-7)M), glibenclamide (10(-6)M) and BaCl(2) (3 x 10(-5)M), respectively, did not alter the concentration-response curves to acetylcholine and NaNO(2). Na+-K+ ATPase pump inhibition with ouabain (10(-5)M) practically abolished acetylcholine and NaNO(2) relaxations. Our findings suggest that acetylcholine-induced relaxation is largely mediated through the NO-cGMP pathway, involving apamin plus ChTx-sensitive K+ and K(v) channels, and Na+-K+-ATPase pump activation.
本研究旨在探讨钾通道是否在猪内乳动脉（IMA）中一氧化氮（NO）依赖性乙酰胆碱舒张中发挥作用。分离并将 IMA 段置于器官浴中以记录等长张力。用毒蕈碱受体阻断剂阿托品（10(-6)M）消除乙酰胆碱引起的血管舒张。孵育吲哚美辛（3 x 10(-6)M）、超氧化物歧化酶（150 U/ml）和 bosentan（10(-5)M）不改变乙酰胆碱反应，排除环氧化酶衍生产物、活性氧或内皮素的参与。使用 L-NOArg（10(-4)M）或 ODQ（3 x 10(-6)M）分别抑制一氧化氮合酶或可溶性鸟苷酸环化酶，强烈减弱乙酰胆碱的松弛反应。当用富含 K+溶液（30 mM）收缩环时，乙酰胆碱和一氧化氮供体（NaNO(2)）诱导的血管舒张减少，电压依赖性 K+（K(v)）通道用 4-氨基吡啶（4-AP；10(-4)M）阻断，Ca2+激活的 K+（K(Ca)）通道用四乙铵（TEA；10(-3)M）阻断，并用 apamin（5 x 10(-7)M）加 charybdotoxin（ChTx；10(-7)M）阻断，但单独添加这些药物时则不然。相比之下，用 iberiotoxin（IbTx；10(-7)M）、glibenclamide（10(-6)M）和 BaCl(2)（3 x 10(-5)M）分别阻断大电导 K(Ca)（BK(Ca)）、ATP 敏感性 K+（K(ATP)）和内向整流 K+（K(ir)）通道，对乙酰胆碱和 NaNO(2)的浓度-反应曲线没有影响。用哇巴因（10(-5)M）抑制 Na+-K+ATP 酶泵，几乎消除了乙酰胆碱和 NaNO(2)的松弛作用。我们的发现表明，乙酰胆碱诱导的松弛主要通过 NO-cGMP 途径介导，涉及 apamin 加 ChTx 敏感的 K+和 K(v)通道以及 Na+-K+-ATP 酶泵的激活。
