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Volume 26, Issue 1
Displaying 1-8 of 8 articles from this issue
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Ei-ichi KOKUE, Toyoaki HAYAMA1976 Volume 26 Issue 1 Pages 1-8
Published: 1976
Released on J-STAGE: June 07, 2011
JOURNAL FREE ACCESSThe action of secretin (SN) on the exocrine pancreas in the chicken was studied in comparison with the rat and dog. Hydrochloric acid (0.1N), pepton (5%) and olive oil were introduced into the small intestine of conscious chickens with chronic pancreatic fistula and caused the volume and protein output to increase slightly in about two-thirds of the chickens tested. The percent increase of the volume output in anesthetized chickens by HCl instillation was only one-tenth of that in the rat. Acid extracts of the intestinal mucosa (80mg) from chickens when given intravenously to rats caused the volume of secretion from the rat pancreas to increase about twofold, whereas the extracts from the dogs' and rats' intestine increased the volume output 5.9 and 5.5times respectively. The increase of pancreatic secretion in chickens by intravenous injection of commercial SN was about one-third of that in the rat. The present studies indicate that SN or a SN-like hormone may be present in the chicken, but it plays only a minor physiological role.View full abstractDownload PDF (852K) -
Kenzo AKAZAWA, Makoto YAMAMOTO, Katsuhiko FUJII, Hidenobu MASHIMA1976 Volume 26 Issue 1 Pages 9-28
Published: 1976
Released on J-STAGE: June 07, 2011
JOURNAL FREE ACCESSA mechanochemical model for muscle contraction was presented which consisted of three subsystems: the regulatory mechanism of contraction by Ca ion, the cross-bridge cycle coupled with actin-myosin interaction and the dynamics of contraction with an external load. It was assumed that both the rate constant of the cross-bridge cycle and the net force of the cross-bridge were linear functions of the sliding velocity. Most parameters in the model were determined from the experimental data, but several were estimated by simulation techniques. The model adequately described the force-load-velocity relation, the rates of energy and heat output as well as some basic mechanical properties of muscle. Not only the steady-state contraction but also the twitch response could be explained by the model. Time courses of tension and shortening during isometric and isotonic twitches were calculated by the model on a digital computer. The calculated curves agreed satisfactorily with the experimental ones obtained from the frog semitendinosus muscle. The rate of tension rise of the isometric twitch was shown to attain the peak at nearly the same time as does the calculated Ca concentration curve.View full abstractDownload PDF (1781K) -
Norio AKAIKE, Masayasu SATO1976 Volume 26 Issue 1 Pages 29-40
Published: 1976
Released on J-STAGE: June 07, 2011
JOURNAL FREE ACCESSEffects of some bitter-tasting compounds on frog taste receptors were examined by recording glossopharyngeal nerve responses. The order of effectiveness of the compounds was quinine>brucine>formanilide>caffeine>urea. When the effects of quinine, brucine and caffeine on electrical responses in taste cells were examined, they all produced a depolarization associated with an increased input resistance. The action of the three compounds on taste receptors therefore, operates with a similar mechanism. The electrical responses in cells, produced by quinine, progressed slowly with time. Such effects with quinine are similar to those with procaine. After adaptation to quinine, the nerve responses to various chemical stimuli were gradually reduced in magnitude, while the electrical responses in taste cells during stimulation by chemicals became smaller. The mechanism of the effects of bitter stimuli are discussed in light of recent findings on the interaction of bitter stimuli with lipid monolayers and the extraction of lipid from bovine taste papillae by bitter stimuli.View full abstractDownload PDF (1142K) -
Hiromichi OHKAWA1976 Volume 26 Issue 1 Pages 41-52
Published: 1976
Released on J-STAGE: June 07, 2011
JOURNAL FREE ACCESSEffects of catecholamines and their inhibitors on the electrical activity of the smooth muscle of the guinea-pig stomach were studied by using pressure electrodes. The spontaneous electrical activity of antrum and corpus preparations consisted of slow waves with or without superimposed spikes. In quiescent fundus preparations, the spike activity and slow waves were generated by TEA. Catecholamines (noradrenaline, isoprenaline and adrenaline) suppressed or blocked the spike discharges and the generation of slow waves. However, the spike activity was enhanced at a higher concentration of phenylephrine in the antrum and fundus preparations. Inhibitory responses of the smooth muscles from whole regions to adrenaline, noradrenaline or isoprenaline were antagonized by propranolol or DCI but not by phentolamine or phenoxybenzamine. Therefore, inhibitory actions of these amines appear to involve beta-adrenoceptors. After treatment with tetrodotoxin, noradrenaline and isoprenaline blocked the spike activity and the generation of slow waves. Phenylephrine or adrenaline potentiated the spike activity in the presence of tetrodotoxin. After treatment with DCI or propranolol, phenylephrine potentiated the spike activity of the antrum and fundus preparations. These excitatory effects were antagonized by phentolamine or phenoxybenzamine. It is concluded that excitatory actions of these amines are mediated by alpha-adrenoceptors rather than via a nervous pathway.View full abstractDownload PDF (1184K) -
Ikuo HOMMA, Satoshi KURIHARA, Toshio SAKAI1976 Volume 26 Issue 1 Pages 53-61
Published: 1976
Released on J-STAGE: June 07, 2011
JOURNAL FREE ACCESSDantrolene sodium (1.0 to 10.0μg/ml) inhibited twitch tension, tetanus tension, and contracture induced by potassium and low concentration of caffeine in the frog toe muscles. The drug also inhibited rapid cooling contracture (RCC), i. e., contracture caused by rapidly cooling the muscle from room temperature to 0°C after immersing it in Ringer's solution containing a subthreshold concentration of caffeine. The drug also suppressed RCC in depolarized muscle fibres which were treated with high concentration of potassium. Comparing the effect of the drug on twitches augmented with nitrate and with caffeine, the former was more markedly inhibited than the latter.
On the basis of these results, the possibility that the drug acts mainly by inhibiting the movement of “trigger calcium” which in turn releases calcium from the sarcoplasmic reticulum is discussed.View full abstractDownload PDF (866K) -
Kyozo KOKETSU, Masaki NAKAMURA1976 Volume 26 Issue 1 Pages 63-77
Published: 1976
Released on J-STAGE: June 07, 2011
JOURNAL FREE ACCESSBullfrog sympathetic ganglion cells produced hyperpolarizing (Ad-hyperpolarization) and depolarizing (Ad-depolarization) responses when adrenaline (Ad) was directly applied to ganglia. The nature of Ad-hyperpolarization recorded by the sucrose-gap method was analysed in the present experiment, in order to clarify its electrogenesis. The amplitude of Ad-hyperpolarization was increased or decreased while ganglion cell membranes were hyperpolarized or depolarized, respectively, by applying a moderate conditioning current to the ganglia. The Adhyperpolarization was depressed in K+-rich solutions as well as in K+-deficient solutions. It was not significantly altered by replacing the extracellular total Cl ions by equimolar glutamate or thiosulfate ions. Ad-hyperpolarization was depressed and finally abolished in the Na+-free Tris solution, and was reversibly eliminated in the solution where Na ions weretotally replaced by equimolar Li ions. It was enhanced when a preparation was previously perfused in the K+-free, Na+-rich solution for certain periods, during which the intracellular Na+ concentration might be increased. Ad-hyperpolarization was depressed by lowering the temperature and by the action of ouabain, and the amplitude of Ad-hyperpolarization was markedly increased in the presence of TEA. The ionic mechanism underlying the generation of Ad-hyperpolarization was discussed on the basis of these present experimental results, and it was suggested that Ad-hyperpolarization might be generated by an electrogenic sodium pump.View full abstractDownload PDF (1569K) -
Yutaka IGARASHI, Yoshitaka SAITO, Masayoshi HIMUKAI, Takeshi HOSHI1976 Volume 26 Issue 1 Pages 79-92
Published: 1976
Released on J-STAGE: June 07, 2011
JOURNAL FREE ACCESSThe nature of maltose- and trehalose-induced electrical potential increments across everted small intestines of toads were investigated. A Michaelis-Menten-like relation was seen between the amplitude of PD increments (ΔPD) and the mucosal concentration of disaccharides over a wide range of concentration, but, at a higher concentration range, Lineweaver-Burk type plot of data always deviated from the linear line for the low and moderate concentration range.The extrapolation of the linear segment of the plots intercepted the ordinate at the same point as that of the line for the glucose-induced potential increments. Both the disaccharide-and the glucose-evoked potentials were not additive and were equally sensitive to phlorizin.Tris depressed the disaccharideevoked potentials to about the same extent as that of inhibition of enzyme activities.The amplitude and time course of the disaccharideinduced potentials, however, could not be accounted for by the mucosal concentration of liberated glucose. These qualitative and quantitative characteristics were explained properly on the basis of a simple well-type local pool for liberated glucose assumed to exist at the brush border. In conclusion, a close functional linkage between brush border membrane disaccharidase activities and the electrogenic hexose transport is well reflected in the disaccharide-evoked potentials in the small intestine.View full abstractDownload PDF (1533K) -
Akinori NOMA, Hiroshi IRISAWA1976 Volume 26 Issue 1 Pages 93-99
Published: 1976
Released on J-STAGE: June 07, 2011
JOURNAL FREE ACCESSTo clarify the role of Ca ion in the rising phase of the sinoatrial (S-A) node action potential, the sigmoidal relationship between the maximum rate of rise of the action potential and the maximum diastolic potential was examined at various concentrations of Ca. The membrane potential was changed by applying a current across a single sucrose gap. The sigmoidal curve shifted toward the positive potential without a change in maximum value when the Ca concentration was increased from nominal “zero” to 10mm. Therefore, it is concluded that Ca ion modifies the inactivation process of Na current which is responsible for the rapid rising phase of the S-A node action potential. The duration of the action potential and the maximum diastolic potential were decreased with an increase in Ca concentration. The observation that the overshoot of the action potential increased by 12 mV for a tenfold increase in concentration of Ca (within the range of 0.1-5.0 mm) suggests that the inward current of Ca ion may be responsible for the overshoot of the S-A node action potential.View full abstractDownload PDF (606K)
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