Issei Takayanagi

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1. The effects of 12-O-tetradecanoyl 4 beta-phorbol 13-acetate (beta-TPA) on the inositol 1,4,5-trisphosphate (IP3) production, Ca2+ release from the intracellular Ca2+ stores and sensitization of contractile apparatus, induced by prostaglandin F2 alpha (PGF2 alpha) and U46619, a thromboxane A2-mimetic, were studied, using fura-2-loaded and -unloaded rat(More)
1. The stereoselectivities of beta-adrenergic partial agonists for the high affinity binding site of beta-adrenoceptors in the guinea-pig ciliary body, right atria and trachea were studied. 2. The inhibition curves by the S(-)-isomers of befunolol and carteolol were not significantly different from that by the R(+)-isomers in the guinea-pig ciliary body. 3.(More)
Nicotine-induced contraction of the isolated guinea pig bronchial preparation was abolished by capsaicin and a substance P (SP) antagonist [( D-Arg1,D-Pro2,D-Trp7,9,Leu11]SP). Nicotine increased the release of immunoreactive SP from the preparations. The nicotine-evoked release of immunoreactive SP from the bronchial preparation was reduced by hexamethonium(More)
1. Carbachol produced a relaxation of dilator muscle at a concentration lower than 1 microM and a contraction at a concentration higher than 1 microM. 2. We studied the effects of the M1-selective antagonist, pirenzepine, the M2-selective antagonist, himbacine, the M3-selective antagonist, 4-diphenyl-acetoxy-N-methylpiperidine methiodide (4-DAMP) and the(More)
Two kinds of spikes, a single-spike unit and burst unit, were obtained by a glass suction electrode recording from neurons in Auerbach's plexus of the guinea pig ileum. Both spikes were inhibited by tetrodotoxin but not by Mn<SUP>2+</SUP>. Frequency of the single-spike unit was increased by nicotine and high concentrations of acetyl choline. The(More)
Contractile responses to substance P, physalaemin and eledoisin, three members of the tachykinin family, were compared and characterized in rabbit iris sphincter smooth muscle. Eledoisin and physalaemin were approximately 5 times more potent than substance P, and the maximum responses to substance P and physalaemin were about 85 percent of those to(More)
The mechanisms of the beta-adrenoceptor-mediated relaxation induced by noradrenaline in guinea pig taenia caecum were investigated. Noradrenaline caused graded relaxation of this preparation. However, the concentration-response curves for noradrenaline were unaffected by propranolol (approximately 10(-5) M) or phentolamine (approximately 10(-5) M). The(More)
In organ bath studies, the selectivity of isolated femoral vein and artery of rabbit to isosorbide dinitrate (ISDN), 5-isosorbide mononitrate (ISMN), major metabolite of ISDN, and glyceryl trinitrate (GTN) was compared. The femoral vein and artery contracted by norepinephrine were relaxed by all the nitro compounds dose-dependently. Potency order was GTN(More)
1. The effects of ryanodine on changes in cytoplasmic Ca2+ level ([Ca2+]i) and muscle tension induced by maximum concentrations of phenylephrine (Phe; 1 microM), prostaglandin F2 alpha (PGF2 alpha, 10 microM), caffeine (Caf, 30 mM) and isoprenaline (Iso, 1 microM) were examined in rat aortic strips using fura-2. 2. In normal media, Phe and PGF2 alpha(More)
beta-Adrenoceptors in the guinea pig taenia caecum were investigated by measuring relaxation responses to agonists and by a radioligand binding assay using [3H]CGP 12177. The rightward shift of the isoprenaline concentration-response curve was observed by butoxamine, a beta 2-selective antagonist, and the pA2 value for butoxamine was 6.46. In control(More)