Role of a novel tetrodotoxin-resistant sodium channel in the nitrergic relaxation of rattlesnake corpus cavernosum
نویسنده
چکیده
Main outcome measures Cumulative concentration-response curves were constructed for acetylcholine (ACh), sodium nitroprusside (SNP), 5-cyclopropyl-2-[1-(2-fluorobenzyl)-1H-pyrazolo [3,4-b]pyridine-3-yl]pyrimidin-4-ylamine (BAY 41-2272), and tadalafil in CCC precontracted with phenylephrine. Relaxation induced by electrical field stimulation (EFS) was also done in the absence and presence of Nw nitroL-arginine methyl ester (L-NAME;100 μM), 1H-[1, 2, 4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 μM) and tetrodotoxin (TTX; 1 μM). Results The hemipenes consisted of two functionally concentric corpora cavernosa, one of them containing radiating bundles of smooth muscle fibers (confirmed by a-actin immunostaining). Endothelial and neural nitric oxide synthases were present in the endothelium and neural structures, respectively; whereas soluble guanylate cyclase and PDE5 were expressed in trabecular smooth muscle. ACh and SNP relaxed isolated CCC, with the relaxations being markedly reduced by L-NAME and ODQ, respectively. BAY 41-2272 and tadalafil caused sustained relaxations with potency (pEC50) values of 5.84 +0.17 and 5.10 + 0.08 (N = 3–4), respectively. In precontracted CCC, EFS caused frequency-dependent relaxations that lasted three times longer than those in mammalian CC. Although these relaxations were almost abolished by either L-NAME or ODQ, they were unaffected by TTX. In contrast, EFS-induced relaxations in marmoset CC were abolished by TTX.
منابع مشابه
اثر سیروز صفراوی بر پاسخهای شلشدگی القاء شده با تحریک الکتریکی اعصاب غیرآدرنرژیک غیرکولینرژیک در کورپوس کاورنوزوم موشهای صحرایی: نقش مسیر نیتریکاکساید و کانابینوئیدهای اندوژن
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