Rand M J, Li C G
Department of Pharmacology, University of Melbourne, Victoria, Australia.
Eur J Pharmacol. 1993 Sep 14;241(2-3):249-54. doi: 10.1016/0014-2999(93)90210-9.
In aortic rings, hydroxocobalamin (30 microM) reduced the relaxant actions of S-nitrosocysteine (0.1-3 microM), S-nitrosoglutathione (0.1-3 microM) and S-nitroso-N-acetylpenicillamine (SNAP, 0.01-3 microM), but did not affect the relaxant action of S-nitroso-coenzyme A (0.1-3 microM). In anococcygeus muscles, hydroxocobalamin (30 microM) had little effect on relaxations produced by nitrosocysteine (0.1-3 microM) and SNAP (0.01-1 microM), and enhanced those produced by nitrosoglutathione (0.1-3 microM) and nitroso-coenzyme A (0.1-3 microM). Since hydroxocobalamin is thought to act like haemoglobin by sequestering NO, some of the effects of hydroxocobalamin were compared with those of haemoglobin. Haemoglobin (10 microM) inhibited relaxations of aortic rings produced by nitrosocysteine and nitrosoglutathione and relaxations of anococcygeus muscles produced by nitrosocysteine, nitrosoglutathione and SNAP. Thus the effects of hydroxocobalamin on nitrosothiol-induced relaxations differ between the rat aorta and anococcygeus muscle, and depend on the exact nature of the nitrosothiol; however, the effects of haemoglobin did not differ qualitatively between the two tissues. Since hydroxocobalamin reduced relaxations of rat anococcygeus muscles elicited by NO, but not those elicited by nitrergic nerve stimulation or nitrosothiols, the nitrergic transmitter more closely resembles a nitrosothiol than free NO. Of those tested, the best correspondence was with nitrosocysteine; however, there were some differences between it and the transmitter.
在主动脉环中，羟钴胺素（30微摩尔）可降低S-亚硝基半胱氨酸（0.1 - 3微摩尔）、S-亚硝基谷胱甘肽（0.1 - 3微摩尔）和S-亚硝基-N-乙酰青霉胺（SNAP，0.01 - 3微摩尔）的舒张作用，但不影响S-亚硝基辅酶A（0.1 - 3微摩尔）的舒张作用。在肛尾肌中，羟钴胺素（30微摩尔）对亚硝基半胱氨酸（0.1 - 3微摩尔）和SNAP（0.01 - 1微摩尔）引起的舒张作用影响不大，而增强了亚硝基谷胱甘肽（0.1 - 3微摩尔）和亚硝基辅酶A（0.1 - 3微摩尔）引起的舒张作用。由于羟钴胺素被认为通过螯合一氧化氮而发挥类似血红蛋白的作用，因此将羟钴胺素的一些作用与血红蛋白的作用进行了比较。血红蛋白（10微摩尔）可抑制亚硝基半胱氨酸和亚硝基谷胱甘肽引起的主动脉环舒张以及亚硝基半胱氨酸、亚硝基谷胱甘肽和SNAP引起的肛尾肌舒张。因此，羟钴胺素对亚硝基硫醇诱导的舒张作用在大鼠主动脉和肛尾肌之间存在差异，并且取决于亚硝基硫醇的确切性质；然而，血红蛋白在这两种组织中的作用在性质上没有差异。由于羟钴胺素可降低大鼠肛尾肌由一氧化氮引起的舒张，但不影响由氮能神经刺激或亚硝基硫醇引起的舒张，因此氮能递质更类似于亚硝基硫醇而非游离的一氧化氮。在测试的物质中，与亚硝基半胱氨酸的对应性最好；然而，它与递质之间仍存在一些差异。
