O Yagasaki

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Oral or intravenous administration of allethrin, a synthetic derivative of the pirethrin-based insecticides, produces neurotoxic symptoms consisting of mild salivation, hyperexcitability, tremors and convulsions which result in death. Intracerebroventricular injection of allethrin to mouse at about one-nineth the dose of intravenous administration, produced(More)
Stimulation of the hypogastric nerve to the guinea pig vas deferens induced biphasic contraction consisting of a rapid transient phase (mediated by ATP) and a delayed tonic phase (mediated by norepinephrine, NE), whereas stimulations in the presence of selective antagonists caused each contractile phase separately. Stimulation in the absence of antagonist(More)
To clarify the mechanism of exocytosis in neurotransmitter release, the fusion of synaptic vesicles with presynaptic membranes prepared from rat brain synaptosomes and concomitant acetylcholine (ACh) release induced by fusion of them were studied in vitro. Fusion of the synaptic vesicles with presynaptic membranes was measured by a fluorescence-dequenching(More)
1. Quantal release of transmitter was measured intracellularly at mouse neuromuscular junctions in the presence and absence of ryanodine (Rnd). 2. Rnd at concentrations up to 1 microM did not significantly alter the frequency of miniature endplate potentials (m.e.p.ps) in the presence or absence of Ca2+, suggesting that Rnd is unlikely to alter the internal(More)
1. The effects of several conditions and agents on the twin-pulse facilitation of the release of transmitter at the mouse neuromuscular junction in low-Ca2+ high-Mg2+ bathing solutions were examined. 2. Twin-pulses gave two endplate potential (epps) with first (m2) and second (m2) quantal contents. The ratio of m2/m1 was taken as a measure of the degree of(More)
1. Prostaglandin E (PGE) may be essential for maintaining the sensitivity of the myenteric plexus of guinea-pig ileum to nicotine. The contributions of prostaglandins to nervous activity evoked by different stimuli have now been investigated by measuring the amount of acetylcholine (ACh) released from the myenteric plexus of the guinea-pig ileum. 2. The(More)
Release of acetylcholine (ACh) by prostaglandin E1 from the nerve terminals of the guinea-pig longitudinal muscle strip was studied in order to reveal the effect of PGE1 on myenteric plexus activity. The ACh released was collected in the presence of physostigmine (2.1 microgram ml-1) and choline (0.1 microgram ml-1) at 38 degrees C. Five to 100 ng ml-1 PGE1(More)
1. The mediators of non-adrenergic non-cholinergic (NANC) relaxation of the longitudinal muscle of rat proximal, middle and distal colon were examined in vitro. 2. Electrical transmural stimulation (TMS) of proximal, middle and distal segments of rat colon induced NANC relaxations which were inhibited by tetrodotoxin (1 microM), but not by atropine (1(More)
The susceptibility of thymocytes from STS/A to radiation-induced cell death was compared with that of thymocytes from BALB/cHeA. After in vitro exposure to 12 Gy X-ray, thymocytes were incubated at 37 degrees C for 8 h and then cell mortality was assessed by 0.02% erythrosin B exclusion. Cell death took place from 2 h in the incubation period, reaching a(More)
The effects of L-type calcium channel antagonists and omega-conotoxin on the contractile responses of guinea pig vas deferens were examined in vitro. Electrical stimulation of the postganglionic hypogastric nerve induced biphasic contraction consisting of rapid phasic and delayed tonic components. L-type calcium channel antagonists, such as diltiazem,(More)