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1. Descending inhibition in the proximal and distal portions of rat colon was studied separately, in vitro. 2. In the proximal colon, localized distension with a small balloon caused three types of response (contraction; relaxation; relaxation, then contraction) of the circular muscle on the anal side of the distended region. 3. Distension caused descending(More)
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)
Possible mediators of descending inhibition in the rat proximal colon were studied. Localized distension with a small balloon caused relaxation of the circular muscle on the anal side of the distended region. This relaxation was still observed after the colonic segment had been desensitized to ATP, neurotensin and vasoactive intestinal peptide, so these(More)
The role of sialic acid in the frequency of miniature endplate potentials (MEPPs) was examined using neuraminidase and gangliosides in the mouse diaphragm. Neuraminidase increased and decreased MEPP frequency in normal K+ and high K+ solution, respectively. The effects were dependent on the presence of Ca2+ in extracellular medium. Neuraminidase liberated(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)
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)
Cadmium ion (Cd2+) was examined for effects on frequency of miniature end-plate potentials (m.e.p.p.s) under several conditions in mouse diaphragm muscles. Cd2+ depressed potassium (K+)-stimulated rise in m.e.p.p. frequency, acting antagonistically to Ca2+, whereas in the absence of K+ stimulation Cd2+ produced a time- and concentration-dependent rise in(More)
The effects of local distension of the intestinal wall on the release of acetylcholine (ACh) from the adjacent non-distended part were studied with the segment os isolated guinea pig ileum. Local distension of the intestinal wall induced the increased release of ACh in the distended part and in its anal side but not in its oral side. Such aboral release of(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)