摘要:

AbstractThe respiratory activity of mitochondria isolated from the outer and inner layers of the ventricular myocardium and from the white and deep red myotornal muscles of juvenileThunnus thynnushas been compared. The highest values for the succinate oxidase and succinate cytochrome c reductase activities have been found in the mitochondria of the outer myocardial layer, followed by mitochondria of the deep red muscle, the inner myocardial layer and the white muscle in that order. Differences in mitochondrial NADH‐cytochrome c reductase activity run parallel, in a lower order of magnitude, to the differences in the oxidation of succinate. This finding is discussed in relation to the different metabolic attitudes of the muscle tissues towards anaerobic glycolysis. The outer myocardial layer of the juvenile tuna ventricle has been shown to have a higher metabolic activity than the inner layer, in contrast to the situation in adult ventricular myocardiu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05818.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe effects of changes in acid‐base parameters on the active force of isolated rabbit papillary muscles were studied at contraction frequencies of 12, 60 and 120/min. When extracellular pH was lowered from 7.4 to 7.0 and 6.7 in a bathing solution buffered with 10 mM histidine, the active force decreased at all contraction frequencies studied. After parallel increases of HCO3concentration (up to 47 mM) and Pco2at a constant extracellular pH of 7.4 the active force of the muscle increased at low and decreased at high contraction frequencies. None of these effects can be attributed to catecholamine release or to altered extracellular concentration of ionized calcium. The inotropic effects produced by bicarbonate were not reproducible by methyl sulfate (47 mM) or propionate (47 mM). It is concluded that: 1. a lowering of the extracellular pH has a negative inotropic effect at all frequencies, 2. HCO3has a positive inotropic effect that is most pronounced at low contraction frequencies and 3. CO2has a negative inotropic effect exceeding that produced by the mere reduction in extracellular pH. The cellular mechanisms involved in the various inotropic effects are discusse

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05819.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe effects of changes in acid‐base parameters on the resting membrane potential, action potential characteristics and propagation velocity were studied in isolated rabbit papillary muscles. Lowering extracellular pH from 7.4 to 6.7 in a bathing solution buffered with 10 mM histidine did not alter the resting membrane potential or action potential characteristics but caused a slight reduction in propagation velocity. A parallel increase in HCO3concentration (up to 47 mM) and Pco2at a constant extracellular pH of 7.4 caused a substantial decrease in action potential duration but did not alter the resting membrane potential or propagation velocity. The decrease in action potential duration was caused by the increase in HCO3concentration. Propionate (47 mM) caused a shortening of the action potential which was of the same magnitude as for HCO3but methylsulfate (47 mM) did not have this effect. The possible influence of these changes on the inotropic state of the myocardium and the cellular mechanisms involved are discusse

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05820.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe neural mechanisms involved in the detection of natural complex sounds were studied by recording single‐neuron responses from 132 cells in the primary auditory cortex of the cat. The cats were paralyzed and under neuroleptanalgesia (NLA). The cells were first stimulated with pure tones; the responses were then compared with those evoked by many different types of complex sounds, most of which were animal vocalizations. Per‐stimulus‐time (PST) histograms constructed from the responses to repetitive stimuli were compared with the corresponding sound spectrograms formed from the sounds used as stimuli. Of 100 cells 68 per cent gave predictable responses to complex sounds on the basis of their responses to different pure tone frequencies. In 32 per cent of the cells the responses were unpredictable. Half of these cells did not react to pure tones at all but responded to one or more animal vocalizations or generator sounds with different patterns. Some cells reacted to pure tones in quite a different way than to certain complex sounds,e.g. with inhibition instead of excitation. These results indicate that cells in the primary auditory cortex of the cat reacting in an unpredictable way to sounds with a complex structure have a more or less specialized function, in detecting and analyzing natural and other complex sound patterns. Cells reacting phasically to pure tones seem to be involved in the detection of transient sound ele

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05821.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe anterior branch of the left coronary artery of the rat heart was ligated and the effects of anoxia on adrenergic nerves were studied histochemically using formaldehyde‐induced fluorescence for localization of norepinephrine. Greenish catecholamine fluorescence was associated in the normal or infarcted myocardium only with adrenergic nerves. Constant but not prominent changes were seen in adrenergic nerve fibers 2 or 4 h after ligation of the coronary artery; the number of delicate adrenergic fibers was reduced and some diffusion of the histochemical reaction was seen in small areas of the infarcted myocardium. Strong effects of anoxia were seen 8 h or more after ligation of the coronary artery. These were characterized by a prominent diffusion of the histochemical reaction and gradual disappearance of adrenergic structures in 2 to 4 days of anoxia. During the healing phase the appearance of numerous adrenergic nerve fibers was closely connected with the ingrowth of a new vascular bed into the infarction area. The observations indicate that adrenergic nervous structures of the myocardium resist the effects of anoxia, which may indicate the viability of sympathetic nerves in the infarcted area during long periods of anoxi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05822.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractIn vitrostudies with the neurotoxic compounds 6‐hydroxydopamine (6‐OH‐DA) and 6‐aminodopamine (6‐A‐DA) showed that noradrenaline (NA) markedly inhibited the autooxidation of 6‐OH‐DA, but not of 6‐A‐DA.In vivostudies of the adrenergic nerves in rat iris showed that the neurotoxic potency of 6‐OH‐DA, but not 6‐A‐DA, was increased after NA depletion by α‐methyl‐p‐tyrosine methylester(H44/68). Neurotoxicity was evaluated by measuring the associated decrease in3H‐NA uptake. lntraocular injection of NA counteracted the degenerative action of 6‐OH‐DA in both untreated and H44168 pretreated rats. Intraocular NA did not interfere with the neurotoxicity of 6‐A‐DA. Additionally, octopamine did not affect the rate of autooxidation nor the neurotoxic potency of 6‐OH‐DA or 6‐A‐DA. Control experiments with3H‐6‐OH‐DA showed that the intraneuronal NA levels did not significantly affect the intraneuronal accumulation of 6‐OH‐DA. The parallelism between thein vitroresults on autooxidation andin vivodata on neurotoxicity makes it appear that the neurotoxic potency of 6‐OH‐DA and 6‐A‐DA is closely associated with their rates of autooxidation. The control of the degenerative action of 6‐OH‐DA by intraneuronal NA may be mediated via react

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05823.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractIn the isolated cat parotid gland intraarterially applied dibutyryl cyclic AMP (db‐CAMP) (1.0 mM) produced a slow, but often maintained salivary flow. db‐CAMP was also able to potentiate secretion evoked by supramaximal doses of intraarterially applied acetylcholine. Similar secretory effects were obtained also after intraarterial application of theophylline (1.0 mM). The secretory responses due to db‐CAMP or theophylline were unaccompanied by measurable acinar membrane potential changes and stayed unchanged after cutting the parasympathetic innervation of the gland and after blocking both cholinergic and β‐adrenergic receptors with atropine (10‐‐7M), and with D‐(‐)‐N‐isopropyl‐p‐nitrophenol‐ethanol‐amine (INPEA) (10‐‐5M), respectively. The possibility of the existence of an acinar adenylate cyclase system functionally linked to the β‐adrene

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05824.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractBovine neurohypophyses were fractionated by differential and density gradient ultracentrifugation and the Ca2+uptake and ATPase activities in the microsomal, mitochondrial and secretory granule fractions were studied. The microsomal and mitochondrial fractions accumulated Ca2+in the presence of ATP. The accumulation by the latter per mg protein was at least twice as large as by the former. This Ca2+accumulation was accompanied by liberation of inorganic phosphate (Pi). In the presence of sodium azide (2 mM) Ca2+uptake and Piliberation were inhibited in the mitochondrial, but not in the microsomal fraction. Further studies of the microsomal fraction revealed that the ATP‐dependent Ca2+uptake and Piliberation activities were temperature and pH‐dependent and required Mg2+. Both activities were stimulated by very low concentrations of Ca2+(1–10 μM) and were inhibited by EGTA (2 mM). N‐ethyl‐maleimide (2 mM) inhibited both the Ca2+uptake and ATPase activities of the microsomal fraction. These results suggest the presence of a membrane ATPase that is stimulated by both Ca2+and Mg2+. It is suggested that the observed Ca2+uptake activities are involved in maintaining a low axoplasmic free Ca2+concentration, thus playing an important role in the release mechanism of vasopressin by the neuro‐secreto

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05825.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe spinal subarachnoid space was perfused with artificial cerebrospinal fluid (CSF) from the low lumbar level to the middle thoracic level or to the cisterna magna in anesthetized rabbits.3H‐choline,3H‐methyl‐atropine or3H‐decamethonium with carrier in different concentrations was added to the perfusate together with14C‐inulin, the latter serving as a marker of the dilution of the perfusate by original CSF. Choline was eliminated from the perfusate partly by a saturable mechanism probably by an uptake into the spinal cord. About 15 per cent of the radioactivity of the choline infused was recovered from the spinal cord mainly as phosphorylcholine, betaine, and phospholipids. Amphetamine decreased the elimination of choline from ventriculocisternal perfusates and partly inhibited the uptake of choline in rabhit choroid plexusin vitro. In contrast, amphetamine did not influence the saturable elimination of choline in the lumbothoracic perfusion. Neither methylatropine nor decamethonium was eliminated from the perfusate by a saturable mechanism in the lumbothoracic perfusions. However, in perfusions including the cisterna magna methylatropine was partly eliminated by such a mechanism. The concentration of radioactivity in fourth ventricular choroid plexa suggested this structure to be responsible for the saturable part of the elimination. In conclusion, there is no active removal of quaternary amines in general from spinal CSF like the choroid plexus mediated clearance from ventri

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05826.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractIn cats in barbiturate anesthesia extracellular pH and potassium were continuously recorded from brain cortex by implanted microelectrodes. Implantation of the electrodes preserved the low permeability of the blood‐brain‐barrier to HCO3and H+ions as indicated by the development of brainacidosisby i.v. injection of HCO3. Acetazolamide (25 mg/kg) i.v. was followed by a marked brain acidosis which after 10 min had progressed to a drop in pH of 0.203 ± 0.046 (x ± S.D., n = 8). The slowness of the development of acidosis points to a direct effect of the carbonic anhydrase inhibition on the brain tissue. As a further support for this conclusion was considered the finding of a prolonged responsetime of brain pH to HCO3i.v., to CO2inhalation, and to hyperventilation after the acetazolamide inhibition. No changes in brain extracellular potassium were

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1975.tb05827.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY