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Biomedical subjects

M Funakoshi

Publications and source records attributed to M Funakoshi.

At least 55 records · Page 3Linked to original sources
PubMed1988

Amiloride inhibition of responses of rat single chorda tympani fibers to chemical and electrical tongue stimulations.

Amiloride inhibition of single fiber responses of the rat chorda tympani to ionic chemical and electrical tongue stimulations was studied. Amiloride reduced responses to both chemical and electrical stimulations with NaCl or LiCl in most of the single fibers. However, the magnitude of reduction of the response by amiloride varied among the fibers and was greater for chemical than electrical stimulation with NaCl in each fiber. Thirty-two single fibers were divided into two groups, such as 18 high (HAS) and 14 low amiloride-sensitive (LAS) fibers. Percent responses (control, 100%) of the former group to chemical stimulus with NaCl after amiloride ranged from 1.1 to 42.5%, while those of the latter from 72.8 to 108.0%. In HAS fibers, amiloride also reduced responses to KCl and CaCl2, but to a smaller degree than those to NaCl and LiCl. Fifteen out of 18 HAS fibers more strongly responded to a chemical stimulus with 0.1 M NaCl than 0.01 M HCl, while the opposite was true for 13 out of 14 LAS fibers, although the threshold concentration for NaCl was rather lower in LAS fibers than in HAS fibers. These results suggest that there exist at least two different receptor mechanisms for NaCl or LiCl which are amiloride-sensitive and -insensitive, and the observed differences in relative specificities to ionic taste stimuli and sensitivities to amiloride among rat chorda tympani fibers are possibly due to a disproportional distribution of these two receptors.

Amiloride↗
PubMed1988

Voltage- and current-clamp recordings of the receptor potential in mouse taste cell.

Intracellular recordings were obtained using the current-clamp and voltage-clamp techniques. When the taste cell membrane was voltage-clamped, the sucrose stimulus induced an inward current accompanied by a membrane resistance increase while the NaCl stimulus induced an inward current accompanied by a membrane resistance decrease. These phenomena indicated that sucrose and NaCl have quite a different generation mechanism of taste responses.

Animals↗
PubMed1988

Cyclic nucleotides may mediate taste transduction.

Taste stimulus adsorption is believed to occur at the taste cell microvillous membrane. But due to technical difficulties of inserting glass electrodes into the mammalian taste cell, little is known about the mechanisms of taste transduction. Reliable intracellular recordings are necessary to determine the characteristics of taste cells. This has been accomplished previously in the mouse and is reported here. Recent experiments indicated that cyclic nucleotides can act on the inner surface of the membranes of a variety of cells to alter their ion-channel activity, and these substances might act as intracellular transmitters in taste cells. But tight junctions found at the apical membrane of mammalian taste cells do not allow stimuli to enter the taste bud, making it difficult to alter the environment of the taste cell by perfusing with chemical solutions. Here we report that cyclic AMP, cyclic GMP, EGTA or tetraethyl-ammonium electrophoretically injected into the mouse taste cell induce membrane depolarization and increased membrane resistance. These results suggest that a cyclic nucleotide enzymatic cascade, modulated by calcium ions, may mediate the potassium permeability that controls taste, in a way analogous to visual and olfactory transduction.

Animals↗
PubMed1987

Ion specificity of rat chorda tympani fibers to chemical and electrical tongue stimulations.

Responses of rat single chorda tympani fibers to ionic chemical stimuli and anodal tongue stimulations with ionic bathing solutions were examined. Fourteen out of 30 fibers showed the highest sensitivities to NaCl for both chemical and electrical stimulations, whereas the remaining 16 fibers showed almost no ion specificity for electrical stimulation even though most of them have the highest sensitivities to HCl for chemical stimulation. Ion specificity for electrical stimulation was significantly smaller than that for chemical stimulation.

Animals↗
PubMed1987

A quantitative study on the tail flick test in the rat.

Tail flick latency and response temperature were measured in awake rats. Both of these parameters varied with the change in rate of increase of radiant heat stimulus and the area of skin irradiated. The caloric factor applied to the tail before the response occurred was calculated approximately from the time-temperature curves monitored over the tail and the response latencies. The magnitude of the caloric factor over a tentative threshold temperature was the crucial factor for the induction of tail flick response, because it was similar for the various irradiating conditions. It was proposed that analgesic effects in the tail flick test may be expressed using this caloric factor which allows direct comparison of studies in which different base-line latencies are used.

Analgesia↗
PubMed1985

Lipids and apolipoproteins in patients treated with major tranquilizers.

The concentrations of lipids and apolipoproteins in serum from men with chronic schizophrenia who were receiving major tranquilizers (17 receiving phenothiazines and 14 receiving a butyrophenone) were quantitated and compared with serum from male controls (n = 14). Concentrations of high-density lipoprotein cholesterol and apolipoproteins A-I and A-II were significantly lower in the patients than in the controls. Mean apolipoproteins C-II and C-III and very low-density lipoprotein cholesterol levels in the patients receiving phenothiazines were higher than levels in the patients receiving butyrophenone or in the controls. There were no significant differences in levels of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or apolipoproteins B and E. The triglyceride level in patients receiving phenothiazines (163 +/- 65 mg/dl) was higher than that in patients receiving butyrophenone (104 +/- 52 mg/dl). Our data suggest that, with respect to triglyceride metabolism, butyrophenone is more beneficial than are phenothiazines.

Adult↗
PubMed1985

Effect of soybean crude fiber on the concentrations of serum lipids and apolipoproteins in hyperlipemic subjects.

Effect of soybean crude fiber on the concentrations of serum lipids and apolipoproteins in hyperlipemic subjects was examined. The concentrations of serum triglycerides, VLDL triglycerides and VLDL cholesterol were decreased significantly following the administration of soybean crude fiber for 2 months. Neither were significant changes found in total cholesterol, LDL cholesterol, HDL cholesterol, apo A-I, apo A-II, apo C-II and apo B levels, nor in body weight before and after the administration of soybean crude fiber.

Adult↗
PubMed1984

Qualitative discrimination of gustatory stimuli in three different strains of mice.

Qualitative similarities and differences among various taste stimuli were examined by comparing the generalization patterns of a conditioned aversion from single chemicals to other compounds in 3 different strains of mice (BALB, C3H and C57BL mice). It was observed as a common characteristic in all 3 strains of mice that generalization gradients among sugars and saccharin Na appeared in the order sucrose--saccharin Na--fructose--glucose--maltose, in which the closer stimuli generalized more strongly to each other. Strain differences were found in sensitivities to D-phenylalanine and L-proline, which generalized to sugars and saccharin Na in C57BL mice, but not in BALB and C3H mice. These strain differences correspond quite well to those previously observed in the responses of single chorda tympani fibers to these amino acids in the 3 strains of mice. A hierarchical cluster analysis and a multidimensional scaling analysis showed that 15 compounds including the 4 basic taste stimuli (sucrose, NaCl, HCl and quinine-HCl) were classified into 7 different groups according to their behavioral similarities and some amino acids were not grouped with any of the 4 basic taste stimuli in the 3 strains of mice. These results suggest the possibility that mice perceive tastes of these amino acids in a way different from human taste primaries.

Animals↗
PubMed1984

Gustatory neural responses in three different strains of mice.

Taste sensitivity in mice and its strain variation were studied by examining integrated responses and single fiber discharges of the chorda tympani nerve to various taste stimuli in the 3 different strains of mice (BALB, C3H and C57BL mice). A comparison among integrated responses of the 3 strains demonstrated that C57BL mice possess the highest sensitivity to sucrose and the lowest to acids, whereas the opposite is true for BALB mice. These 3 strains of mice commonly possess higher sensitivity to divalent chloride salts than to NaCl. Measures of the breadth of responsiveness showed that single fibers of all 3 strains of mice are relatively more narrowly tuned to taste stimuli than those of rats and hamsters, although the specificity of fibers tends to be greater in the order of C57BL greater than C3H greater than BALB mice. A cluster analysis of fibers demonstrated that two distinct fiber types, a sweet- and Na-type, commonly exist in all 3 strains of mice. The most clear strain difference was found in the sensitivity to D-phenylalanine, which produced good responses in 'sweet-type' fibers of C57BL mice but not in those of C3H and BALB mice. This suggests the possibility that D-phenylalanine has a taste to C57BL mice that is similar to that of sucrose and that it tastes different to C3H and BALB mice.

Animals↗
PubMed1984

The mouse taste cell response to five sugar stimuli.

Intracellular recordings of mouse taste cell responses were made using glass microelectrodes filled with procion yellow dye solution. Only responses recorded from taste buds with fluorescent cells, as observed in subsequent histological preparations, were used in this study. The mouse taste cell depolarizes when stimulated with sucrose and is accompanied by either a resistance increase or no change. On the other hand, a NaCl stimulus produces a depolarization, hyperpolarization or null response and is accompanied by either a membrane resistance decrease or no change. Four sugars other than sucrose (maltose, fructose, glucose and lactose) produced the depolarization or null responses and were accompanied by an increase or no change in membrane resistance. From the above observations, it is suggested that each taste cell produces its own characteristic response profiles and membrane resistance changes for the five sugars and NaCl tested.

Animals↗