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Volume 39, Issue 3
Displaying 1-12 of 12 articles from this issue
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Toshikatsu YOKOTA1989 Volume 39 Issue 3 Pages 335-348
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSIn both cats and Japanese macaques, there are nociceptive specific (NS) and wide dynamic range (WDR) neurons in the shell region of the caudal ventrobasal (VB) complex of the thalamus. This comprises both the nucleus ventralis posteromedialis proper (VPM proper), and the nucleus ventralis posterolateralis (VPL). These two classes of nociceptive neurons are spatially segregated, WDR neurons being located both more anteriorly and in a narrow belt around the VB complex. Both NS and WDR neurons are somatotopically organized. These two classes of nociceptive neurons may constitute a thalamic link in the pain pathway from both the dorsal horn of the spinal cord and its trigeminal homologue, to the primary somatosensory cortex. Visceral sympathetic afferent inputs also project to the VPL part of the shell region of the caudal VB complex, there being viscerosomatic convergence onto both NS and WDR neurons. Visceral and cutaneous pain pathways thus appear to share a common projection locus in the shell region of the caudal VB complex.View full abstractDownload PDF (1400K) -
Ryuji MATSUO, Takashi YAMAMOTO, Kiyomitsu YOSHITAKA, Toshifumi MORIMOT ...1989 Volume 39 Issue 3 Pages 349-357
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSIn order to investigate the neural mechanisms of reflex salivary secretion, experiments were carried out on anesthetized, decerebrate rats from which the volumes of submandibular salivary secretion and the efferent discharges in the preganglionic parasymapathetic fibers innervating the submandibular gland were recorded. Salivary secretion was induced by either infusing a taste solution, or an aliquot of hot water (45-55°C) into the oral cavity, or by pinching the frontal parts of the oral region with a pair of forceps. The reflex salivation induced by noxious thermal and mechanical stimuli was markedly reduced by lesioning either the caudal (VC), or the interpolar (VI) trigeminal sensory nuclei. Taste-elicited salivary secretion was significantly reduced by lesioning the nucleus of the tractus solitarius (NTS). Of 43 preganglionic parasympathetic fibers sampled, 27 responded to both noxious mechanical and thermal stimulation of the oral region, and to electrical stimulation of the VC. Ten fibers responded only to taste stimulation and to electrical stimulation of the NTS. The remaining 6 fibers responded to both taste and noxious thermal stimulation of the oral region. These fibers responded well to NTS stimulation, but gave only a slight response to VC stimulation. These results suggest that two distinct neural pathways exist which mediate reflex salivation in the lower brain stem of the rat, i.e., the taste pathway via the NTS and the nociceptive pathway via the trigeminal sensory nuclei.View full abstractDownload PDF (723K) -
Osamu SHIDO, Yoriko YONEDA, Tetsuo NAGASAKA1989 Volume 39 Issue 3 Pages 359-369
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe effects of intracerebroventricular (icv) vasoactive intestinal polypeptide (VIP), secretin, glucagon, and cholecystokinin-octapeptide (CCK-8) on the thermoregulatory and cardiovascular systems were studied in conscious rats. The icv injection of VIP at a dose of 10μg produced hyperthermia with an increase in the positive difference between the interscapular brown adipose tissue (BAT) and colonic temperatures (TBAT-Tco), but had little effect on nonevaporative heat loss. Mean arterial blood pressure and heart rate increased following the icv VIP. The results were consistent at ambient temperatures (Ta) of 18, 23, and 28°C. The icv injection of secretin at doses of 1 and 10μg at Ta of 23°C produced hypothermia with a decrease in (TBAT-Tco) and elevated blood pressure without any change in heart rate. The 10μg of icv glucagon had no effect on the thermoregulatory and cardiovascular systems. The large dose of icv CCK-8 (10μg) induced persistent hyperthermia. Nonsulfated-form CCK-8 and CCK-tetrapeptide, however, were ineffective on all variables measured. These results indicate that the central VIP activates BAT thermogenesis and induces hyperthermia, but has a minimum effect on nonevaporative heat loss. Although VIP, secretin, and glucagon have similarities in terms of chemical structure, their effects on body temperature, BAT thermogenesis, and the cardiovascular system are quite different.View full abstractDownload PDF (776K) -
Hiroshi MIYOSHI, Issei SEYAMA1989 Volume 39 Issue 3 Pages 371-383
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe characteristics of sodium currents (INa) in single frog ventricular cells were studied with the oil gap method. This method improves time-and space-control of the membrane potential under the voltage clamp, thereby making possible accurate analysis of fast events of INa. In this preparation the threshold of INa was about -60mV and the reversal potential was 58mV, which is close to the value calculated by the Nernst equation for sodium ions. Because the instantaneous current-voltage (I-V) relationship is linear, the ease of permeation of sodium ions through Na+ channels is well expressed by the chord conductance. The falling phase of INa and the time course of recovery from inactivation follow a time course of single exponential function. The time constants for on- and off-processes of inactivation at the same membrane potential are very close to each other, indicating only a single state of inactivation. Though almost all properties of INa were well described by Hodgkin-Huxley's model, a clear delay of onset of inactivation was demonstrated by two-pulse experiment. In this report the modified kinetics scheme was proposed which can account for both a delay of onset of inactivation development and a falling phase of INa that follows a single exponential time course.View full abstractDownload PDF (877K) -
Hiroaki TAKEKURA, Toshitada YOSHIOKA1989 Volume 39 Issue 3 Pages 385-396
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe relationships between ultrastructural and metabolic profiles in different types of single muscle fiber after hindlimb suspension in rats were examined. Glycolytic (lactate dehydrogenase, LDH; phosphofructokinase, PFK) and oxidative (succinate dehydrogenase, SDH; malate dehydrogenase, MDH) enzyme activities in extensor digitorum longus (EDL) and soleus (SOL) muscles were measured. Relative mitochondrial and lipid droplet volumes were also measured in single muscle fiber of different types. Glycolytic enzyme activity in EDL muscle and oxidative enzyme activity in soleus muscle decreased following suspension for 2 weeks. LDH and PFK activities in fast-twitch (FG, fast-twitch glycolytic; FOG, fast-twitch oxidative glycolytic) fibers and oxidative enzymes in FOG and FG fibers decreased following suspension. Relative mitochondrial volume decreased significantly in all types (SO, slow-twitch oxidative; FOG, and FG) of fibers following suspension. The mitochondrial volume in SO fiber of the control group was significantly (p<0.01) higher than that of suspended group; however, SDH and MDH activities were not different between the control and suspended groups. The structural and metabolic changes following hindlimb suspension were influenced by different factors, respectively. Changes in ultrastructural and metabolic profiles in response to the hindlimb suspension differed according to the type of fibers.View full abstractDownload PDF (899K) -
Katsuji TAKEDA, Tomoko OOHARA, Kaoru TABEI, Yasushi ASANO1989 Volume 39 Issue 3 Pages 397-410
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe regulation of proton transport and cytosolic pH+ was studied in rat papillary collecting duct (PCD) cells in culture using a pH+-sensitive fluorescence probe, 2, 7-bis-carboxyethyl-5, 6-carboxyfluorescein (BCECF). Data were obtained from confluent monolayers grown on glass coverslips and dipped in a H+CO3--free medium, pH+ 7.40. The resting intracellular pH+ (pH+i) was 7.16±0.03 (n=20). When PCD cells had been acidified by pretreatment with NH+4Cl, pH+i immediately recovered toward the resting value. Two mechanisms participated in this recovery: a Na++-dependent mechanism which could be inhibited by amiloride (indicative of Na++-H++ exchanger) and a Na++-independent process (a proton ATPase). The pH+i recovery from acid loading was inhibited by amiloride to about 55% of the control recovery (half-maximal effect at 100μM). The rate of pH+i recovery after the readdition of Na++ to a sodium-free medium exhibited saturation kinetics (half maximal rate at 28mM). Dicyclohexylcarbodiimide (DCCD), an inhibitor of a plasma membrane proton ATPase, and the depletion of cellular ATP induced by 2mM potassium cyanide (KCN) also partially inhibited the rate of pH+i recovery after cell acidification with a NH+4Cl load. When PCD cells were treated with 1mM DCCD, amiloride almost completely inhibited pH+i, recovery. Amiloride and the removal of external Na++ had induced a gradual fall in pH+i to a new resting value and rapidly recovered when Na++ was added. We conclude that PCD cells grown in culture have at least two proton transport mechanisms: a Na++-H++ exchanger and a plasma membrane proton ATPase. The kinetics of these processes can be reliably assessed by the pH+-sensitive fluorescent probe, BCECF. Both the Na++-H++ exchanger and the plasma membrane proton ATPase may contribute to urinary acidification.View full abstractDownload PDF (1026K) -
Yoshimi MIYAMOTO, Kyuichi NIIZEKI, Koichi KAWAHARA, Katsuhiko DOI1989 Volume 39 Issue 3 Pages 411-420
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSIn order to know the role of cardiodynamic factors for exercise hyperpnea, ventilation and several cardiorespiratory variables were measured simultaneously in human subjects during exercise. Cardiac output (Q) and mixed venous CO2 content (CvCO2) were determined by a rebreathing method. The correlation coefficients (r) for the relationships between minute expiratory ventilation (VE) and each of end-tidal CO2 tension (PETCO2), Q, CvCO2, CO2 flow into the lung (QCO2, the product of Q and CvCO2), oxygen consumption (VO2), and CO2 output (VCO2) were determined during the steady-state exercise up to 90W. The correlation was highly significant (r=0.84-0.99, p<0.001) in each case except for PETCO2 (r=0.13, N.S.). The highest correlation was observed in the VE-VCO2 relationship. It was assume that VCO2 released from the pulmonary capillaries into the alveoli is the most likely stimulus leading to exercise hyperpnea. Arterial CO2 oscillation may be regarded as a potential linkage between VCO2 and VE.View full abstractDownload PDF (699K) -
Kazuhiro SUGAHARA, Taketoshi KIYOTA, Tomoko BABA, Mari NAKAMURA, Tohru ...1989 Volume 39 Issue 3 Pages 421-428
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSActive ion transport by the airway epithelium plays an important role in maintaining the effective defense mechanisms of theairway by regulating the volume and composition of the airway fluid. We investigated the abilities of adrenergic agents, cholinergic agents, and chemical mediators to modulate ion transport in canine tracheal epithelium, using Ussing-type chambers. Transepithelial electric potential difference (PD), resistance (R), and short circuit current (SCC) of the tracheal epithelium were measured before and during exposure to a drug or after a change in the perfusate composition. The mean values and S.E. (N=41) of PD, R, and SCC during the control period were -18±4mV (luminal negative to submucosa), 240±42Ω•cm2, and 50±5μA/cm2, respectively. Ouabain (10-4M), an inhibitor of Na+-K+-ATPase, in the mucosal bath abolished PD and SCC. Replacement of luminal Na by choline reversibly reduced PD and SCC. These findings suggest that PD and SCC of the tracheal epithelium are maintained by the transcellular transport of luminal Na toward the mucosa. Isoproterenol (10-5M), epinephrine (10-4M), and norepinephrine (10-4M) markedly increased both PD and SCC. Acetylcholine (10-4M) and histamine (10-4M) did not alter SCC significantly. Prostaglandin E1 (10-6M) and F2α (10-5M) slightly increased PD and SCC. These results indicate that adrenergic and cholinergic agents induce different patterns of effect on ion transport (adrenergic-dominant) in the tracheal epithelium. Thus, the effects of autonomic agents and chemical mediators on ion transport may explain, in part, the pathogenesis of airway disorders observed in many respiratory diseases.View full abstractDownload PDF (566K) -
Panagiota KOUNINIOTOU-KRONTIRI, Stylianos TSAKIRIS1989 Volume 39 Issue 3 Pages 429-440
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe mean miniature end-plate potential (m.e.p.p.) frequency and the acetylcholinesterase (AChE) activity have been examined in the rat diaphragm, in relation to the time of Li+ action. Substitution of LiCl for NaCl caused increase in m.e.p.p. frequency, the final level of which depended on Li+ concentration in the bath solution. Incubation of diaphragm homogenate with NaCl caused initially a slight increase of AChE activity, reaching a plateau after 20min. Substitution of LiCl for NaCl produced an increase in AChE activity to a maximum, followed by a decrease to a minimum. The activity consequently returned to a steady level. During complete substitution of LiCl for NaCl, the maximum value of AChE activity coincided with the maximum m.e.p.p. frequency (Fmax) induced by Li+; the minimum value correlated with the precise instant that the frequency reached a plateau. The addition of prostigmine caused: a) blockade of AChE activity, and b) prostigmine concentration-dependent decrease of Fmax and/or disappearance of m.e.p.p.s from neuromuscular junctions treated with Li+. These results are discussed in terms of correlation between changes of AChE activity induced by Li+ and variations of spontaneous quantal release of the transmitter from nerve terminals of the rat diaphragm treated with Li+.View full abstractDownload PDF (895K) -
Kyuichi NIIZEKI, Yoshimi MIYAMOTO, Katsuhiko DOI1989 Volume 39 Issue 3 Pages 441-446
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSCardiac output was determined by impedance cardiography (Q(imp)) and a rebreathing method (Q(reb)) during exercise of loads up to 90W. The correlation between Q(imp) and Q(reb) was generally good, but it was found in two of four subjects that Q(imp) was slightly lower than Q(reb) at the higher exercise levels. The regression equation for both Q values was: Q(imp)=0.91Q(reb)+0.25 (l/min, r=0.87, p<0.001).View full abstractDownload PDF (360K) -
Tetsuya IZAWA, Takao KOMABAYASHI, Kazuhiro SUDA, Shouhachiro SHINODA, ...1989 Volume 39 Issue 3 Pages 447-454
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSAn acute dynamic exercise provokes the translocation of β-adrenergic receptors (β-AR) from light vesicle fractions to sarcolemmal membranes in rat myocardium. However, 15min after an acute exercise the density of β-AR in both fractions returned to the pre-exercise level. The mean maximal activity of adenylate cyclase in response to isoproterenol roughly paralleled the redistribution of β-AR. The dose-response curves, however, were substantially shifted to the right with increase in EC50 for isoproterenol stimulation of adenylate cyclase. Thus, the sensitivity of sarcolemmal β-AR was found to be blunted 15min afterwards.View full abstractDownload PDF (601K) -
Hachiro INOMATA, Tomofumi MIMATA, Makoto WAKUI, Ke-Yi ZHANG1989 Volume 39 Issue 3 Pages 455-460
Published: 1989
Released on J-STAGE: July 28, 2006
JOURNAL FREE ACCESSThe actions of noradrenaline (NA) on the smooth muscle of the guinea-pig vas deferens in tetraethylammonium (TEA) medium have been studied under constant-current and voltage-clamp conditions. The marked changes observed during exposure to NA are 1) slowness in the rising phase of the action potential, delay in the falling phase and reduction in the amplitude, and 2) depression of the voltage-dependent Ca2+ current with a negative shift of its reversal potential as well as with a reduction in its conductance. These findings might suggest that NA application stimulates the voltage-independent Ca2+ machinery, but suppresses the voltage-dependent Ca2+ machinery through membrane.View full abstractDownload PDF (447K)
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