Search PubMed⌕ Search

Biomedical subjects

K Morimoto

Publications and source records attributed to K Morimoto.

At least 685 records · Page 38Linked to original sources
PubMed1982

Role of monoamines in afferent synaptic transmission in frog taste organ.

To examine physiological and pharmacological characteristics of synaptic transmission from taste cells to afferent nerve terminals in frog taste organ, changes in the glossopharyngeal nerve discharges and responses to chemical stimulation of the tongue were examined by intra-arterially perfusing the tongue with Ringer solution containing monoamines and their related substances. Noradrenaline (NA), dopamine (DA), and adrenaline (AD) produced an increase in the spontaneous glossopharyngeal nerve discharges as well as an enhancement of taste responses to various kinds of chemical stimuli, but they did not affect tactile response. NA was the most effective of the three. Monoamine-releasing agents, tyramine and 6OHDA, enhanced spontaneous nerve discharges but depressed taste responses. Antimonoaminergic agents, phentolamine and phenoxybenzamine (alpha-blockers), increased nerve discharges and depressed taste responses, but did not affect tactile response. DCI (beta-blocker), except at high concentrations, affected neither nerve discharges nor taste responses. Pre-treatment of frogs with monoamine-depleting agents, alpha-MPT and 6OHDA, depressed taste responses. Reserpine enhanced the effect of alpha-MPT. The depressed taste responses recovered after perfusion of the tongue with NA. From the results obtained, the possibility of NA being a transmitter at the afferent synapse in the frog taste organ was discussed.

Action Potentials↗
PubMed1982

Active and inactive renins in human urine.

Urinary excretions of active and inactive renin were studied in normal subjects and in patients with hypertensive or renal disease. Excessive excretion of active and inactive renins was observed in some patients with no significant correlation to their plasma levels or the degree of proteinuria. Inactive renin excretion correlated to active renin excretion, but the clearance was lower than that of the active form. No correlation was found between the urinary kallikrein excretion and the active/inactive renin ratio in the urine or the plasma. Urinary renin activity was increased by acidification and by trypsin treatment, but not by cold exposure. Both active and inactive renins in the urine showed multiple peaks corresponding to molecular weights between 45,000 and 64,000 by gel filtration.

Cold Temperature↗
PubMed1982

Neural factors affecting the muscle activity of the human mesotubarium ovarica at ovulatory phase.

Histochemical and in vitro investigations of the autonomic innervation in the human mesotubarium ovarica (MTO) are described here in the course of our studying its physiologic role in the capture of released oocytes at ovulation. The present results imply that the muscle activity of MTO is under the excitatory control of cholinergic nerves and under a reciprocal (predominantly excitatory) control of adrenergic nerves, and that both adrenergic and cholinergic neural factors (at least postsynaptic ones) are related in the enhancement of the muscle activity of MTO around the time of ovulation.

Acetylcholine↗
PubMed1982

[An ultrastructural study of capillary permeability of rabbit ovarian follicles using horseradish peroxidase as a tracer (author's transl)].

In the previous study, using carbon tracer, we reported the ultrastructural evidences which suggested the increased capillary permeability of preovulatory rabbit ovarian follicles. In the present study, another tracer, horseradish peroxidase (HRP 50 A in diameter, mw. 40,000), being smaller than carbon particle, was used to examine the permeability of perifollicular capillaries. HRP left capillaries and appeared in the follicular cavity immediately after the injection into aorta, through all stages of follicular development. In the capillaries, the narrow interendothelial clefts (about 100-200 A in width) were observed through preovulatory stages. Fenestrations were noted at 3,4,6 hours after the hCG injection, and interendothelial gaps (about 1,000-10,000 A in width) were seen at 10, 12 hours. HRP passed through these structures and infiltrated the capillary basal lamina and the basal lamina of the follicle and went through the intercellular spaces between granulosa cells. Therefore, the increased permeability of perifollicular capillaries, just prior to ovulation, were not so obvious as when carbon particles were used. On the other hand, carbon particles, injected via marginal ear vein, were incorporated in the endothelial vesicles 15 min. after its administration and retained beneath the basal lamina outside the follicle within 60 min. These observations indicated that "blood follicle barrier" consisting of capillary endothelium, basal lamina, basal lamina of the follicle and granulosa layer played an inhibitory role to large molecules but not to small molecules.

Animals↗
PubMed1981

Progesterone-induced smooth muscle-like cells in the subperitoneal nodules produced by estrogen. Experimental approach to leiomyomatosis peritonealis disseminata.

In order to examine the pathogenesis and histogenesis of leiomyomatosis peritonealis disseminata (LPD), guinea pigs were treated with various doses of estradiol benzoate (E) (40, 80, 100, and 200 microgram/day, three times a week, by intramuscular injection). After treatment for 3 months, each dose of E produced lesions simulating the disseminated pattern of LPD. Ultrastructurally, the nodules were considered to be composed of cells resembling those of fibroblast. In guinea pigs, pretreatment with estradiol benzoate (100 microgram/day, three times a week intramuscularly for 3 months followed by combination treatment with E and progesterone (P) (0.5 and 1.0 mg/day, once a week, intramuscularly) for 1 to 3 months produced nodules similar to those with estrogen alone. Ultrastructurally, these nodules were composed of cells resembling smooth muscle and decidual cells. According to these results, we conjectured that estrogen differentiates and proliferates cells with the features of fibroblast-like cells from the subcoelomic totipotential mesenchyme, and these cells are differentiated into smooth muscle-like cells and decidua-like cells under the influence of both estrogen and progesterone, resulting in the production of multiple subperitoneal nodules.

Abdominal Neoplasms↗
PubMed1981

Physiological characteristics of low threshold mechanoreceptor afferent units innervating frog skin.

A total of ninety-three mechanoreceptor afferent units with fast conducting axons in the sciatic nerve innervating the plantar and lateral surface of the hind foot were isolated for electrophysiological recording in anaesthetized frogs (Rana catesbeiana). Sixty-three rapidly adapting (RA) units and thirty slowly adapting (SA) units were differentiated from each other mainly on the presence of an "off' response and a slope-locked "on' response to ramp stimulation in RA units and on the persistence of discharges of the SA units during steady pressure on the receptive field. RA units were subdivided into two subgroups; RA type I units and RA type II units. The RA type I units had small well-demarcated receptive fields in which the unit was uniformly sensitive, and low indentation amplitude and velocity thresholds. The RA type II units had receptive fields consisting of several sensitive spots, associated with skin warts in the warty skin, high indentation thresholds, and the fastest conduction velocities (mean 19.9+/-4.4 m/sec) among the three groups of the units studied. RA type I units showed U-shaped tuning curves with a best tuning frequency at around 2 Hz, while tuning curves of SA units were flat from 0.1 (the lowest frequency examined) to 1 Hz. RA type II units could only follow the first cycle of continuous sinusoidal stimulation at any frequency. The relation between the indentation velocity and amplitude of the ramp and the spike discharges was analysed quantitatively.

Action Potentials↗
PubMed1981

Calcium current-dependent and voltage-dependent inactivation of calcium channels in Helix aspersa.

1. Inactivation of the Ca channels has been examined in isolated nerve cell bodies of Helix aspersa using the suction pipette method for voltage clamp and internal perfusion.2. Satisfactory suppression of outward currents was essential. This was achieved over most of the voltage range by substitution of Cs ion for K ion and by the use of TEA intra- and extracellularly and 4-AP extracellularly. A small time- and voltage-dependent non-specific current remained at potentials above +60 mV.3. In these solutions, Ca current approaches E(Ca) but cannot be detected in the outward direction. The Ca channel appears to be impermeable to Cs and Tris ions.4. Inactivation of Ca currents occurs as a bi-exponential process. The faster rate is 10-20 times the slower rate and is about one twentieth the rate of activation. The development of inactivation during a single voltage-clamp step and the onset of inactivation produced by prepulses followed after brief intervals by a test pulse, have roughly similar time courses.5. The rates of inactivation increase monotonically at potentials more positive than about -25 mV. The amount of steady-state inactivation increases with membrane depolarizations to potentials of about +50 mV. At more positive potentials, steady-state inactivation is reduced.6. Intracellular EGTA slows the faster rate of inactivation of I(Ca) and reduces the amount of steady-state inactivation measured with a standard two pulse protocol. The effect is specifically related to Ca chelation and hydrogen ions are not involved. This component of inactivation is referred to as Ca current-dependent inactivation and is consistent with observations that increased Ca(i) inactivates the Ca channel. The process does not depend upon current flow alone since Ba currents of comparable or greater magnitude have smaller initial rates of inactivation. Furthermore, application of Ba ion intracellularly in large concentrations has no effect on steady-state inactivation.7. The bi-exponential inactivation process that persists in the presence of EGTA(i) is similar to that occurring when extracellular Ba ion carries current through the Ca channel. Steady-state inactivation also persists and is similar in the two cases. Therefore it is concluded that inactivation is voltage-dependent as well as Ca current-dependent.8. Diffusion models that included reasonable values for the effect of binding on diffusion, even when combined with declining influxes, did not account for this ;mixed' form of calcium- and voltage-dependent inactivation. A compartmental model in which the particular kinetic model of voltage-dependent inactivation was not critical described the Ca current-dependent inactivation.

Animals↗
PubMed1981

Distribution of cephalothin to the exudate in comparison with the plasma or lymph concentrations in croton oil-induced inflammatory rats.

The transport of cephalothin (CET) to the exudate was investigated in croton oil-induced inflammatory rats following the intramuscular administration of CET-aqueous solution, CEt-O/W emulsion, or CET-W/O emulsion. The lymphatic transport of CET was the highest following the administration of W/O emulsion. The exudate level of CET was in a decreasing order of W/O emulsion, O/W emulsion, and aqueous solution. In the rat whose blood vessels at femoral rectus, the site of administration, were ligated, the plasma level was decreased by the administration of aqueous solution, but not by W/O emulsion. The exudate level of CET was significantly higher in case of W/O emulsion. Possible mechanisms involved are discussed.

Animals↗