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Biomedical subjects

F Ito

Publications and source records attributed to F Ito.

At least 289 records · Page 16Linked to original sources
PubMed1977

Frog muscle spindles with unbranched myelinated afferent axons: the response to stretch and the length of the first myelinated segment.

1. Twenty-five muscle spindles innervated by unbranched myelinated axons in the capsule were isolated from sartorius muscle in young frogs (2-2--9-5 g in weight, 28-47 mm in rostro-caudal length). 2. The lengths and the diameters of the first myelinated segments varied from 30 to 170 mum and from 9 to 20 mum respectively. There was no relationship between the lengths and the diameters. 3. Dynamic and static components were analysed from discharge rates of the muscle spindles during ramp-and-hold stretches of 0-8 mm from different initial lengths. The values of the dynamic components to a certain stretch stimulation increased with shortening in the length of the first myelinated segment. The values of the static components were independent in length. 4. The amplitudes of action potentials recorded from the spindle terminal decreased during the dynamic phase of the stretch. The ratio of amplitude decrease at the end of the dynamic phase versus the initial length depended upon the length of the first myelinated segment. 5. These results suggest that the discharges during stretch may arise at the first node, though the spontaneous discharges may be generated at the terminal.

Action Potentials↗
PubMed1976

Sensory terminal responses of frog muscle spindle recorded across vaseline gap onto intrafusal muscle fibre.

When electrical activities of the sensory terminal in the frog muscle spindle were recorded across a vaseline gap which was oriented transversely to the intrafusal muscle bundle (IFM-gap), large and small spikes occurred in coincidence with propagated and abortive spikes respectively recorded across the axon-gap. The IFM-gap placed on the receptor region displayed triphasic spikes in which the first small positive deflection occurred approximately 0.2 ms prior to the propagated and abortive spikes. No such deflection was observed when the IFM-gap was placed more than 50 mum away from the receptor region. Increasing the distance from the receptor region to the IFM-gap resulted in an exponential decay in the amplitudes of both the large and small spikes. Regardless of the position of the IFM-gap relative to the receptor region, bimodal distributions in the amplitude histograms of the large spikes, and large variations in the shapes of the small spikes were observed. These results indicate that the IFM-gap responses may represent electrical activity of the non-myelinated branches, along which propagated impulses may arise from at lest two separate origins, while abortive spikes arise from many more sites.

Action Potentials↗
PubMed1975

Skin reaction, inhibition of macrophage migration, and lymphocyte transformation with tuberculin active peptide (TAP) and arabinogalactan obtained from tubercle bacilli.

Arabinogalactan purified from heat-killed tubercle bacilli failed to elicit a delayed type of skin reaction and had no ability to induce in vitro lymphocyte blast formation in sensitized guinea pigs. It was, however, inhibitory to migration of bronchoalveolar washing cells by the indirect test, but not by the direct test, and capable of eliciting an immediate type of skin reaction and anaphylaxis when injected into sensitized guinea pigs. Tuberculin active peptide (TAP) was active in all of in vitro and in vivo cell-mediated immune responses, but not in immediate responses.

Anaphylaxis↗
PubMed1974

Structural and functional asymmetries of myelinated branches in the frog muscle spindle.

1. Most of the axons innervating single-type muscle spindles in the frog sartorius muscle divide into myelinated branches at a node; one of the branches subdivides (Bs) and the other does not (Bn).2. Electrical responses at the afferent nerve terminal of the isolated spindles were recorded extracellularly and intracellularly with micro-electrodes, concurrently with the terminal responses by the paraffin gap method.3. By recording spontaneous orthodromic and provoked antidromic impulses and by stimulating the nerve terminals with micro-electrodes and inactivating the terminals with micro-application of potassium ion, it was deduced that propagated and abortive spikes are almost always generated at the terminal of Bn (Tn), not at the terminals of Bs (Ta and Tb).4. The site of impulse initiation, as determined in (3), was found, after measurement of the lengths of the myelinated branches in each preparation, to be essentially the terminal nearest the parent axon.5. Selective inactivation of Tn by far-ultra-violet light removed both propagated and abortive spikes. Both types of spikes survived after irradiation of Ta and Tb, although the relationship between spike frequency and spindle stretch was altered. The same results were obtained after transection of the branches with a laser microbeam.

Animals↗