Detail of "86247-86-1"

Reference

Actions of nipradilol (K-351), a new a- and b-adrenoceptor blocker, on the rabbit portal vein

Actions of nipradilol (K-351), a new a- and b-adrenoceptor blocker, on the rabbit portal vein. Nanjo, Tamaki; Kitamura, Kenji (Fac. Med., Kyushu Univ., Fukuoka 812, Japan). Jpn. J. Pharmacol., 35(4), 359-69 (English) 1984. CODEN: JJPAAZ. ISSN: 0021-5198. DOCUMENT TYPE: Journal CA Section: 1 (Pharmacology) Section cross-reference(s): 2 Nipradilol [81486-22-8], but not denitronipradilol [86247-86-1], inhibited the norepinephrine (NE) [51-41-2]-induced depolarization and contraction of the rabbit portal vein. The NE-induced contraction and depolarization were also blocked by prazosin, but not by yohimbine. Therefore, nipradilol possesses an a1-blocking action. The order of potency was prazosin > nipradilol > yohimbine > denitronipradilol = 0. With applications of field stimulations to muscle tissues, the smooth muscle membrane was depolarized with a latency of several seconds, and the action potential was generated. These phenomena were blocked by tetrodotoxin (TTX), prazosin, or nipradilol, but not by yohimbine. Isoproterenol (Isop) [7683-59-2] inhibited the 30 mM K+-induced contraction, and this inhibitory action was dose-dependently blocked by denitronipradilol, nipradilol, or propranolol. The potency of the b-blocking actions of nipradilol was much the same as that obsd. by propranolol and denitronipradilol. When nipradilol (10-5M) was applied to the tissue, the amplitude of the 30 mM K+ contraction was slightly reduced. Such inhibitory action was not obsd. by application of denitronipradilol. The Ki values of nipradilol for blocking actions on the NE-induced contraction and Isop-induced relaxation were of the same order, 10-7M. Therefore, the potencies of a1-blocking and b-blocking actions of nipradilol may be the same in the rabbit portal vein. Thus, vasodilating action of nipradilol on the rabbit portal vein is mainly due to its a1-blocking action; the nitroglycerin-like action induced by the nitrate residue may be less important for relaxation of the rabbit portal vein.