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Volume 35 (1985)
- Issue 6 Pages 875-
- Issue 5 Pages 693-
- Issue 4 Pages 535-
- Issue 3 Pages 375-
- Issue 2 Pages 179-
- Issue 1 Pages 1-
Volume 35, Issue 6
Displaying 1-19 of 19 articles from this issue
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Masayasu SATO1985 Volume 35 Issue 6 Pages 875-885
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSChemicals of diverse structures can elicit sweet response in humans, but marked species difference in response to sweet-tasting compounds exists among mammalinan species. In a number of species a distinct group of chorda tympani nerve fibers predominantly responds to sucrose and Na saccharin. Sweet response in certain mammals can be selectively blocked by a number of compounds, including gymnemic acid and ziziphin. Cu and Zn salts also selectively suppress chorda tympani nerve response to sweet stimuli in rodents. Probably Cu2+and Zn2+ compete with sweet stimuli for binding to receptor molecules. A recent attempt to isolate a protein from monkey tongues revealed the presence of a thaumatin-binding protein of M.W. of approximately 50, 000. This protein was predominantly found in taste papillae, with lesser amounts found in non-taste tissue.View full abstractDownload PDF (929K) -
Masatsugu NAKAI, Yoko YAMANE, Yukihisa UMEDA, Jin YAMAMOTO, Koichi OGI ...1985 Volume 35 Issue 6 Pages 887-901
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSElectrical stimulation of the intermediate portion of the solitary nucleus (SOL) is known to consistently elicit a pressor response and increase in the release of vasopressin (VP) in rats, when the cervical spinal cord and vago-sympathetic trunks are cut. The aim of the present study was to provide a methodological assessment for this technique, in order to quantify the central neuroendocrine function to release VP. Experiments were conducted on rats with cervical cordotomy and vagotomy, under 60% N2O anesthesia and artificial ventilation. The animals were maintained at their normal arterial blood pressure by infusing phenylephrine, which itself exerted little influence on the arterial plasma VP concentration (pVP) during SOL stimulation. In order to prevent blood loss, cross circulation with a donor rat was utilized in the blood sampling for pVP determination. We confirmed that this technique itself did not significantly affect the pVP level. A monopolar stimulus at a frequency of 50Hz was found to produce the pressor response most effectively. The current spread of the stimulation (0.5ms duration; 1s on/1s off; up to at least 120μA) did not induce a false-positive pressor response mediated by other structures adjacent to the SOL. We suggest that electrical stimulation of the SOL in rats with cervical cordotomy and vagotomy, for observing the pressor response and/or increase of pVP, represents a rapid approach for screening the overall function of the ascending efferent part of the reflex mechanisms to release VP.View full abstractDownload PDF (1176K) -
Keiji MARUTA, Yumiko MIZOGUCHI, Takuro OSA1985 Volume 35 Issue 6 Pages 903-915
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSEffects of polyamines (0.05-1.2mM) on the mechanical and electrical activities in the circular muscles of pre-(day 20 of pregnancy) and post-partum (10-15h after delivery) rat myometria were studied. In the prepartum preparations, spermine and spermidine, added to the Mg-free Krebs solution, depressed contractions in a dose-dependent manner, whereas cadaverine and putrescine potentiated them. The latter agents depressed contractions when preparations were treated with indomethacin. Plateau potentials were spontaneously generated in the Mg-free solution in the prepartum circular muscle. The duration of the plateau became shorter, and spike potentials supermounted on the plateau potential were depressed when spermine or spermidine was applied. In the postpartum preparations, spike activity was depressed by spermine and spermidine. In both pre- and post-partum preparations, the membrane activity was little affected by cadaverine and putrescine. In view of the above findings, it was hypothesized that polyamines in general took the place of divalent cations in causing membrane stabilization. Cadaverine and putrescine probably caused a potentiation of contraction by stimulating the synthesis of endogenous prostaglandins.View full abstractDownload PDF (995K) -
Yutaka IMOTO, Tsuguhisa EHARA, Masayosi GOTO1985 Volume 35 Issue 6 Pages 917-932
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSChanges in membrane currents seen in Ca-free, EGTA (1mM)- containing Tyrode solution (EGTA Tyrode), were studied in isolated guinea-pig ventricular cells, under the voltage clamp performed with a "GΩ seal" patch electrode. Application of the EGTA Tyrode (calculated [Ca]0=1.3×10-9M) first eliminated the usual calcium current, but induced an extra inward current within 2min. The reversal potential of this current, as judged by the direction of the current change, was about +25mV (without correction of a liquid junction potential of -12mV), but above this voltage a decaying outward current was observed. The decay of these inward and outward currents during depolarization was slow, but a large, nearly time-independent component was evident. These currents, regardless of their polarity and time course, were reduced by application of verapamil (10-5M) and Mg (5mM), and were inactivated by pre-depolarizations. In Na-free EGTA Tyrode, the inward current disappeared but the outward current persisted at high voltages. These results suggest that in ventricular cells, reduction of external Ca concentrations to a nanomolar range induces a Ca channel current composed of an inward current carried by Na, and an outward current, presumably carried by K ions. Because of the persistence of the apparently non-inactivating Ca channel current, the net membrane current evoked at voltages around 0mV remained close to zero, or even inward, after the decay of the time-dependent component, which was completed within a few hundreds ms. This characteristic I-V relation was considered to be linked to the development of the long-lasting action potentials, with a plateau maintained at around 0mV, in EGTA Tyrode.View full abstractDownload PDF (1095K) -
Noriyuki IWATSUKI, Yoshio MARUYAMA, Osamu MATSUMOTO, Akinori NISHIYAMA1985 Volume 35 Issue 6 Pages 933-944
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSIsolated acinar cells from rat and mouse parotid glands were studied with patch-clamp whole-cell current recordings. Acetylcholine (ACh) stimulation caused a transient inward current at a membrane potential of -70mV, and a sustained outward current at a membrane potential of 0mV, in quasi physiological Na+, K+ ion gradients, except the zero-Cl- ion gradient condition across the membrane. The reversal potential obtained from the ACh-evoked steady current was about -75 mV, in this ionic condition. When major Cl- ions of both the pipette and the bath solution were replaced, either by glutamate or by sulphate, only a large outward current was observed, at a membrane potential of -60mV, in the presence of ACh. The addition of Ca2+-ionophore A23187 caused responses similar to those evoked by ACh. The reversal potential of A23187-induced current was close to the K+ equilibrium potential of -90mV, in a Cl--free condition. When K+-free NaCl solution was used in the pipette and the bath, A23187 caused only a large inward current, at a membrane potential of -60mV. The reversal potential of A23187-evoked current was about -15mV, in a symmetrical K+-free, NaCl condition. These results suggest that the ACh and A23187 activate Cl- as well as K+ conducting pathways via an increase in [Ca2+]i in the parotid acinar cells. The A23187-evoked large K+ current could not be explained solely by a rise in open probability of the channels.View full abstractDownload PDF (889K) -
Masayoshi HIMUKAI1985 Volume 35 Issue 6 Pages 945-952
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe properties of carnosine (Car) and glycylglycine (Gly-Gly), transported across the mucosal border, were studied in isolated guinea pig everted ileum. The initial influxes of both dipeptides could be described by single Michaelis-Menten kinetics, having a nearly equal value of maximum influx. Mutual inhibition studies showed that the inhibition observed between Car and Gly-Gly was fully competitive, indicating that both Car and Gly-Gly share a common carrier. Although carrier-mediated influxes of the dipeptides were independent of Na+, the addition of the dipeptides into the mucosal solution evoked sudden and sustained increments of mucosal negativity. The changes in short-circuit current (ΔIsc) evoked by the peptides increased as the Na+ concentration in the solution was increased, although both dipeptides evoked small increases in Isc, even in the absence of Na+ In spite of these common properties of transport and transport-related electrical phenomena, it was seen that the maximum change in transmural potential difference (ΔPDt max) evoked by Car was about half that of Gly-Gly. Such a discrepancy between coincident Jmax values and values of ΔPDt max suggests that the mechanism of induction of ionic flow is different for these two dipeptides.View full abstractDownload PDF (533K) -
Hiroshi KAWATA1985 Volume 35 Issue 6 Pages 953-972
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSSome features of the electrically induced contracture were investigated by means of the partition polarization method in the toe muscles of a bullfrog. Under the current clamp condition and in the presence of tetrodotoxin, a biphasic contracture was induced by strong depolarizing pulses, 1sec, in duration. The contracture was depressed either by lengthening the pulse interval or by reducing the external calcium concentration. Furthermore, the contracture was augmented by applying conditioning depolarization and inhibited by conditioning hyperpolarization without accompanying any noticeable changes in the test depolarization. Caffeine at a concentration of 1mM depressed the inhibitory effect of pre-hyperpolarization. Strong hyperpolarizing pulses had no effect on the caffeine contracture, whereas a similar pre-hyperpolarization markedly suppressed the phenomenon on the post-contracture potentiation of twitch, induced by a powerful sustained depolarization. From these results it was suggested that calcium ions in the vicinity of the myoplasmic site of the transverse tubular membrane may play some role in generating and regulating the contracture. The possibility of direct contribution of calcium entering from the cell exterior in contracture generation, especially for the slow component, and its regulation was also discussed.View full abstractDownload PDF (1332K) -
Effects of Neurotensin on the Non-adrenergic Inhibitory Neurotransmission in the Guinea-pig DuodenumHiromichi OHKAWA1985 Volume 35 Issue 6 Pages 973-983
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe effects of neurotensin on the non-adrenergic inhibitory neurotransmission in the guinea-pig duodenum were investigated. The resting membrane potential of the duodenal smooth muscle cells was reduced by neurotensin at the concentration of 3×10-8M or more. The amplitude of the non-adrenergic inhibitory potentials was decreased by neurotensin (1-3×10-8M). In the Ca2+-free solution, the amplitude of the inhibitory potentials was also decreased. The increased amplitude of the non-adrenergic inhibitory potentials evoked in the high calcium solution (Ca2+, 5mM) was decreased by neurotensin (10-8M). Neither atropine (1.4×10-6M) nor propranolol (3.4×10-6M) blocked the inhibitory action of neurotensin (10-8M) on the inhibitory potential. The frequency of the spontaneous action potentials of the duodenal smooth muscle cells was strongly increased with accompanying depolarization by neurotensin 8×10-8M. The tonic contraction of the duodenal smooth muscles was produced by neurotensin (3-8×10-8M). The results obtained suggest that neurotensin relates to the non-adrenergic inhibitory pathway in the control mechanism on intestinal motility.View full abstractDownload PDF (736K) -
Nobumasa HARA, Masashi SAWADA, Takashi MAENO1985 Volume 35 Issue 6 Pages 985-1012
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe ionic mechanism of the effect of intracellularly injected adenosine 3′, 5′-cyclic monophosphate (cAMP) on the membrane of identified neuron L5 of Aplysia kurodai was investigated with conventional voltage-clamp and ion-substitution techniques. The intracellular elevation of cAMP caused an inward current (IcAMP), which was not accompanied by a significant change in membrane conductance at potentials more hyperpolarized than -60mV. The current increased over the voltage range (-50 to -30mV) associated with a conductance decrease and decreased at potentials more hyperpolarized than -60mV. Elevated intracellular cAMP was found to enhance a region of negative slope resistance in steady-state I-V relations. Duration of the IcAMP was greatly prolonged by bath-applied isobutylmethylxanthine (50μM), but imidazole (10mM) had an opposite effect on the IcAMP. Tolbutamide (5mM), a protein kinase inhibitor, reduced the IcAMP. The current was not affected by the presence of bath-applied TTX (50μM), ouabain (50μM), or triaminopyrimidine (5mM). Reduction of [Na+]0 reversibly decreased the IcAMP. Li+ could largely substitute for Na+. Alterations of [K+]0, and bath application of 4-AP (5mM) and TEA (30mM) did not affect the IcAMP, In the presence of Na+, Cl-, and divalent cations such as Ca2+ and Ba2+ inhibited the IcAMP. These results suggest that fast elevation of intracellular cAMP induces a TTX-resistant slow Na+ inward current, and the current might be due to activation of cAMP-dependent protein kinase.View full abstractDownload PDF (2229K) -
Junichiro YAMAMOTO, Utako OKAMOTO, Shigeru MORITA, Noriyuki ASADA, Mis ...1985 Volume 35 Issue 6 Pages 1013-1021
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSIt has been speculated that the modified form of plasminogen, a precursor of proteolytic enzyme plasmin in plasma, plays an important role in fibrinolysis in the blood. The present study was undertaken to examine the production by α2-macroglobulin-plasmin complexes. α2-macroglobulin-plasmin complexes were purified from urokinase-activated plasma by affinity chromatography on lysine-Sepharose and gel filtration on Ultrogel AcA 22. The plasmin complex converted native plasminogen into the modified form more easily in the presence of ε-aminocaproic acid. The modification of native plasminogen by α2-macroglobulin-bound plasmin was completely inhibited by aprotinin, and partly by soybean trypsin inhibitor. α2-macroglobulin-bound plasmin produced modified plasminogen in human plasma where potent plasmin inhibitors exist, though the degree of production was small. The present results support the speculation of the important role of the modified form in vivo.View full abstractDownload PDF (673K) -
Sadayoshi TAGUCHI, Yuko HATA, Kazuo ITOH1985 Volume 35 Issue 6 Pages 1023-1032
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSTwenty four male Sprague-Dawley rats, 35 days old, were randomly assigned to one of four groups: 2 resting control groups and 2 swimming groups. The sea level-control and the sea level-swimming groups were housed 5 weeks at 1, 011hPa (760mmHg) while the hypoxic control and swimming groups were housed for 1 week at 678hPa, followed by 4 weeks at 611hPa. The swimming rats were subjected to a swimming program of 30min, 6 days/week for 5 weeks. Both hypoxia groups developed significantly higher Hb and Hct levels than the sea level groups. The glycogen content in the extensor digitorum longus (EDL) and the deep portion of the vastus lateralis (DVL) muscles of the sea level-swimming group were significantly greater as compared to the hypoxia swimming group. The succinate dehydrogenase (SDH) activity in the sea level-control group was significantly lower in the EDL muscle than in the 3 other groups, and in the DVL muscle lower than that of the sea level-swimming group. Histochemically, hypoxia and swimming training induced significant increases in the fast-twitch-oxidative-glycolytic (FOG) fibers (6-11%) in soleus muscle, and decreases in the slow-twitch-oxidative (SO) fibers. The EDL muscles had significantly higher percentages of FOG fibers in the hypoxia and swimming groups than in the sea level-control group. On the basis of the present study it seems probable that hypoxia is a triggering factor for the conversions of muscle fiber types and the increase in oxidative capacity.View full abstractDownload PDF (783K) -
Hisato SAKAMOTO, Takeshi HOSHI1985 Volume 35 Issue 6 Pages 1033-1049
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe mechanism of secretory supply of K+ into the diluting segment of nephron was studied in Triturus kidneys by observing Ba2+ effects on electrical phenomena related to K+ movements and other electrical properties of the segment. Ba2+ (1-2mM) applied into the luminal fluid completely blocked K+ movement into the lumen during the stop-flow of the intraluminal K+-free solution. Also, Ba2+ inhibited transepithelial K+ diffusion potential induced by alterations in the intraluminal K+ concentration and increased transtubular resistance (Rt). A rapidly decaying time course of the K+ diffusion potential and its high peak amplitude (near the maximum expected from an imposed concentration difference) suggest that the diffusion potential was generated across the paracellular pathways. Step-changes in the Na+ concentration induced similar but smaller diffusion potentials, which were also inhibited by Ba2+. Replacement of Cl- with SO42- converted the time courses of both K+ and Na+ diffusion potentials to a sustained type. These suggest that the pathway has a specially high permeability to K+ and lower permeabilities to Na+ and Cl-. Triaminopyrimidine and kinetin similarly blocked K+ movement during stop-flow of a K+-free solution. The low Rt, a unique property of the segment, could be ascribed to the leakiness of the paracellular pathway from the comparison of input resistances of cells and cell surface areas between this segment and the proximal tubule. Based on these findings and other reported data, a novel mechanism of K+ supply was proposed which assumed the presence of a local pool of a high K+ concentration in the paracellular pathway and secretory movement of K+ through intercellular junctional complexes.View full abstractDownload PDF (1395K) -
Juro IRIUCHIJIMA, Shogo SAKATA1985 Volume 35 Issue 6 Pages 1051-1063
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSRegional differences in sympathetic vasoconstrictor tone were studied in conscious rats. In each rat an electromagnetic flow probe was chronically implanted around the common carotid, superior mesenteric, or renal artery, or the terminal aorta. An indwelling catheter for the measurement of arterial pressure was inserted into the terminal aorta via the right femoral artery. Peripheral resistance was calculated by dividing arterial pressure by flow. The per cent decrease in peripheral resistance on the ganglion blockade with hexamethonium bromide was used as a measure of regional sympathetic vasoconstrictor tone. A significant decrease in peripheral resistance, assumed to indicate a substantial tonic discharge to resistance vessels, was observed in conscious rats only in the carotid and renal areas and not in the superior mesenteric and hindquarter (supplied by the terminal aorta) areas. Since ganglion blockade also diminished the sum of the mean regional flows, cardiac output was estimated to decrease on the ganglion blockade. This suggests that capacitance vessels are also receiving a sizable vasoconstrictor tone, because the ganglion blockade did not elevate right atrial pressure. Pentobarbital anesthesia markedly inhibited the assumed tone to the renal area and was estimated to newly generate a tone to the hindquarters.View full abstractDownload PDF (983K) -
Shigeo NAKAJIMA1985 Volume 35 Issue 6 Pages 1065-1077
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe pressure-velocity and pressure-volume relationships were determined in the isolated rabbit left ventricle in order to evaluate ventricular function during global ischemia (low pressure perfusion) and under reperfusion after a 10min complete coronary occlusion (reperfusion after coronary occlusion). Reducing coronary perfusion pressure, the maximum isovolumic pressure (P0) decreased, but the maximum ejection velocity (Vmax) did not. The slope of the end-systolic pressure-volume relationship (Emax) decreased without any significant change in the volume-axis intercept. On the other hand, under reperfusion after coronary occlusion, both P0 and Vmax ware depressed considerably, but Emax quickly recovered to the control level. Thus, Vmax and Emax show different behavior depending on the ischemic conditions. To analyze the relaxation process under low pressure perfusion and reperfusion after coronary occlusion, the pressure-velocity relations during the relaxation phase were determined by the isovelocity method. Similar to the relation for contraction phase, the relation obtained here could be adequately approximated by a hyperbolic equation. Under the control condition, the relaxation velocity was always lower than the contraction velocity at the corresponding pressure level, and the ratio of the maximum filling velocity (Rmax) to Vmax was relatively constant. Although both Rmax and Rmax/Vmax were little affected by the low pressure perfusion, Vmax and Rmax, especially Vmax, decreased when the ventricle was reperfused after coronary occlusion, resulting in an increased Rmax/Vmax.View full abstractDownload PDF (963K) -
Ken HOTTA, Yoshimichi YAMAMOTO, Toshiharu OBA1985 Volume 35 Issue 6 Pages 1079-1083
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSChange of intracellular free Ca in smooth muscle was monitored using Quin 2, Ca sensitive fluorescence dye. Upon electrical stimulus, increase of light emission from the sample occurred in two phases. Procaine and caffeine inhibited and facilitated, respectively, the 2nd phase of intensity change, which coincided with the mechanical response. It is concluded that the released Ca from intracellular store sites may play a key role for the mechanical activation of smooth muscles.View full abstractDownload PDF (299K) -
Takashi NAKAHARI, Manabu MIYAMOTO, Koichi SANO, Hideyo YOSHIDA, Yusuke ...1985 Volume 35 Issue 6 Pages 1085-1090
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSMicroscopic observations were made of volume changes in ECF of the dog submandibular glands during resting state and stimulated state without blood supply. The interlobular space, one of the compartments of ECF, decreased significantly during stimulation when blood supply was absent. The results show that the interlobular space plays an important role as a reservoir of fluid in salivary secretion.View full abstractDownload PDF (632K) -
Kenichiro ODA1985 Volume 35 Issue 6 Pages 1091-1095
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSTo investigate the relationship between motor endplate size and muscle fiber diameter, analyses of 125I-α-bungarotoxin autoradiographs and acetylcholinesterase staining were performed in different muscle groups of the rat. These revealed 1) there is a linear correlation between endplate size and fiber diameter in each muscle group, and 2) each muscle group has a characteristic ratio of endplate size to fiber diameter; the ratios were markedly higher in extraocular muscles than in limb muscles.View full abstractDownload PDF (536K) -
Ke HSU1985 Volume 35 Issue 6 Pages 1097-1100
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSMonophasic action potentials of about 70 and 10mV were recorded by inserting a microelectrode into the axon and the myelin sheath of an intact myelinated fiber, respectively. When the intra-axonal or the intra-myelinic microelectrode was used for both stimulation and recording, only the anodal current was effective in inducing action potentials. The inter-nodal membrane was, therefore, intrinsically inexitable.View full abstractDownload PDF (318K) -
Hiroyuki SOEDA, Fujio SAKUDO, Kenichi NODA1985 Volume 35 Issue 6 Pages 1101-1105
Published: 1985
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSNaCl at various concentrations applied to the dorsal surface of the bullfrog tongue induced slow potential changes across the tongue. They were almost in parallel with changes in impulse discharges simultaneously recorded from the glossopharyngeal nerve.View full abstractDownload PDF (325K)
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