Furukawa K, Itoh T, Kajiwara M, Kitamura K, Suzuki H, Ito Y, Kuriyama H
J Pharmacol Exp Ther. 1981 Jul;218(1):248-59.
Effects of 2-nicotinamidoethyl nitrate (2-NN) on smooth muscle cells of porcine and guinea-pig coronary arteries were investigated by the microelectrode and double sucrose-gap methods and from isometric contractions. In the dose over 2 X 10(-6) M in the guinea-pig coronary artery and over 5 X 10(-6) M in the large and small porcine coronary arteries, the membrane was hyperpolarized and the ionic conductance of the membrane was increased. This hyperpolarization appeared more dominantly in low [K]0. The action was estimated to be due to increase in the K-conductance of the membrane in both species. The spike with an overshoot evoked by electrical stimulation in the presence of tetraethylammonium chloride (TEA) was suppressed by 2-NN, mainly due to hyperpolarization of the membrane and not to suppression of Ca-carriers at the membrane. The contraction evoked by electrical depolarization, acetylcholine (ACh), excess [K]0 or repetitive short pulse stimulation was suppressed in the presence of 2-NN with a concentration similar to that which hyperpolarized the membrane. The suppression of the mechanical response is postulated to be mainly due to hyperpolarization of the membrane and in part to suppression of the Ca-mobilization from the storage sites in the cell. The former seems to be the main action of 2-NN on the coronary arteries in both species. Definite differences on 2-NN actions between the large and small porcine coronary arteries were not observed, but the contraction evoked in the large coronary artery was suppressed slightly more by 2-NN. Vasodilation which occurs with application of 2-NN is discussed in relation to that induced by nitroprusside or nitroglycerin.
采用微电极、双蔗糖间隙法并通过等长收缩研究了2-烟酰胺基乙基硝酸盐（2-NN）对猪和豚鼠冠状动脉平滑肌细胞的作用。在豚鼠冠状动脉中，剂量超过2×10⁻⁶ M，在猪的大、小冠状动脉中剂量超过5×10⁻⁶ M时，细胞膜发生超极化，膜的离子电导增加。这种超极化在低[K]₀时更为明显。据估计，在这两种动物中，该作用是由于细胞膜K电导增加所致。在存在四乙铵（TEA）的情况下，电刺激诱发的有超射的锋电位被2-NN抑制，这主要是由于细胞膜超极化，而非抑制细胞膜上的钙载体。在存在与使细胞膜超极化浓度相似的2-NN时，电去极化、乙酰胆碱（ACh）、过量[K]₀或重复短脉冲刺激所诱发的收缩受到抑制。推测机械反应的抑制主要是由于细胞膜超极化，部分是由于抑制细胞内储存部位的钙动员。前者似乎是2-NN对这两种动物冠状动脉的主要作用。未观察到猪的大、小冠状动脉在2-NN作用上有明显差异，但2-NN对大冠状动脉诱发的收缩抑制作用略强。讨论了应用2-NN时出现的血管舒张与硝普钠或硝酸甘油诱导的血管舒张的关系。
