摘要:

The permeability of gramicidin‐treated human red blood cell membranes to K+and CI‐has been measured at normal ionic strength (1) by tracer exchange at steady‐state distribution of salt, and (2) by net transport of salt in the presence of a salt concentration gradient. Under both conditions KCI was the only inorganic salt in cells and medium. In the studies of self‐exchanges the electrical driving force on the ions was zero. Calculation of permeability coefficients from net salt transport was simplified because the experiment was designed as a special case of the Nernst‐Planck diffusion regime, i.e. the single salt case. Gramicidin altered the cell membranes from being anion to become cation selective. Gramicidin increased the potassium exchange without affecting, the chloride exchange measurably. The chloride exchange showed saturation kinetics as does chloride exchange in normal cells. The net transport of KCI in the presence of a constant concentration gradient increased to a constant value with increasing gramicidin concentration. At high gramicidin concentrations (0°C, pH 7.2) the “chloride permeability coefficient” calculated from tracer exchange (1.9×10‐6cm/s) was 290 times the chloride permeability coefficient calculated from net salt transport (0.65×10‐8cm/s). The latter value corresponds to a chloride conductance of 4.2×10‐6ohm‐1cm‐2. The chloride permeability coefficient was 2.1×10‐8cm/s at 25°C (pH 6.8) indicating a value of 3 for theQ25. It appears that normal red cells are anion selective in the sense that anion permeability exceeds cation permeability with a factor of more than a hundred between 0°C and body temperature. The anion exchange, i.e. the Hamburger shift, is a tightly coupled transport process which is several orders of magnitude faster than a

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06463.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Energy metabolism was studied in nerve endings isolated from 3‐week‐old rat brain. Concentrations of glycogen, glucose, ATP, phosphocreatine and lactate were lower in synaptosomes than in the intact brain. The consumption of these endogenous substrates, the ability to generate high‐energy phosphate, and the production of ammonia were determined in aerobic and anaerobic conditions. Unlike nerve tissue in general, synaptosomes preferentially utilized endogenous ATP and phosphocreatine stores which, on incubation in the absence of exogenous substrates, were emptied long before glycogen stores were exhausted. The optimal medium for respiratory studies was found to have electrolyte concentrations equal to the extracellular fluid. The synaptosomes had an endogenous respiration rate of 6.3 nmol O2mg prot. min, measured with an oxygen electrode, and it probably reflects consumption of their glycogen stores. Glucose usually had no effect on the respiration rate of synaptosomes, but sometimes increased it slightly. However, after incubation in the presence of arsenate synaptosomes showed an increase in respiration when glucose was added. ADP, when added with glucose, also stimulated respiration. Pyruvate and succinate always increased respiration, succinate usually having the stronger effect. The present results show that isolated nerve endings are metabolically intact, which justifies their use in research on neurotransmission. In addition, opposite to the present consensus, synaptic transmission does not seem primarily to depend on the availability of glucose but rather on local stores of high‐energy phosphate co

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06464.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The ACTH/MSH cells of the pars distalis and pars intermedia of the mammalian hypophysis contain peptides with amino‐terminal tryptophan which exhibit a strong fluorescence after treatment with modified formaldehyde vapour methods and with glyoxylic acid in the tissue sections from freeze‐dried specimens. By homogenization of the hypophyses in ethanolic glyoxylic acid and subsequent heating the peptides can be converted to highly fluorescent β‐carboline derivatives; these can then be extracted with glacial acetic acid, separated by silica gel thin‐layer chromatography and identified in UV light. Amino‐terminal tryptophyl peptide from adult human hypophysis extracted and treated in this way gave the structurel‐tryptophylglycine after acid hydrolysis. This structure was subsequently confirmed by producing a fluorescent derivative from authenticl‐tryptophylglycine using the same reaction conditions as for the tissue homogenate. This derivative moved in the same way in thin‐layer chromatography as fluorescent amino‐terminal tryptophyl peptide extracted from human hypophysis. Thereafter a study was made of the antinociceptive effects of authenticl‐tryptophylglycine administered subcutaneously in mice both alone and together with morphine.l‐tryptophylglycine had no antinociceptive effects alone and neither did it change morphine antinociception. Also it had no apparent effects on the behaviour of mice. Thus, ACTH/MSH cells contain a dipeptide whose physiological function differs from the effects of AC

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06465.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The problem of this study was whether the effects produced by alcohol in the posterior parietal association cortex are specific to this drug or shared by other centrally acting depressant drugs such as barbiturates. The effect of graded doses of pentobarbital on multineuronal impulse activity was recorded with transdural microelectrode technique in 30 expts. in Brodmann's area 7 of five stump‐tailed monkeys (Macaca speciosa). The results were compared with those from 32 expts. performed with alcohol and published separately. The dosage of the two drugs was determined on the basis of the monkeys' sensori‐motor coordination which was assessed with a rating scale of reaching accuracy for food rewards. There were several recording sites where the actions of the two drugs were similar at similar behavioural levels of intoxication. However, in the distribution of effects among various functional types of recording sites a significant difference was found between pentobarbital and alcohol. Alcohol commonly diminished cellular activity related to motor behaviour (reaching, grasping) and only rarely responses to somesthetic stimuli, whereas the effects of pentobarbital were the opposite being most common on somatosensory responses and least common on activity related to motor behaviour. Also responses to visual stimuli were more sensitive to pentobarbital than to alcohol. The actions of pentobarbital and alcohol on responses evoked by sensory stimulation differed significantly (P<0.01). We conclude that significant differences exist in the mechanisms of action of alcohol and barbiturate on the associative systems of the br

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06466.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The influence of intravenous infusion of adrenaline (8 μg · kg‐1· min‐1) upon local cerebral blood flow (CBF) in paralyzed and artificially ventilated rats was measured autoradio‐graphically with14C‐iodoantipyrine as the diffusible tracer. At this dose, adrenaline invariably increased local CBF even though blood pressure was close to normal at the time of the CBF measurement. In average, local CBF increased to 400% of control. In 6 of 9 animals the increase in flow was inhomogenous with randomingly distributed areas of very high flow rates. Experiments withi.v.administration of Evans blue prior to infusion of adrenaline showed that areas of Evans blue extravasation appeared in 3 of 4 animals. Although areas of extravasation often corresponded to areas of high flow rates the former were much more circumscribed. Furthermore, very high flow rates were found in areas showing no sign of blood‐brain barrier dysfunction. It is concluded that the increase in CBF was at least partly due to a pressure‐mediated passage of adrenaline across the blood‐brain barrier but that such a passage can occur in the absence of macroscopically visible extravas

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06467.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The effects of colchicine and colchiceine on fast axonal transport in frog sciatic nerves were studied in vitro. Colchiceine inhibited the transport to about the same extent as colchicine. Preincubation at low temperature potentiated the inhibitory effect of either drug. The polymerization of purified brain tubulin was inhibited by colchiceine at 5–10 times higher concentrations than colchicine. The similarity of the effects obtained with colchicine and colchiceine indicates that both drugs arrest axonal transport by interfering with microtubule function. Colchicine and colchiceine did not affect the levels of high energy phosphates (ATP and CrP) in frog nerves indicating that a reduced energy supply was not responsible for the arrested transpor

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06468.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The effects of cholera toxin on tissue osmolality and on net transport rates of water, sodium, chloride and potassium as well as on unidirectional fluxes of water and sodium were studied in vivo. In all experiments the toxin caused a net secretion of water, sodium, chloride and potassium. The unidirectional sodium transport from tissue to lumen was increased while the flux in the opposite direction was reduced 180 min after cholera toxin instillation. Cholera toxin produced only a small reduction in the villous tissue hyperosmolality, created by the intestinal countercurrent exchanger. This reduction was far too small to explain the observed net secretion of fluid and solutes induced by the cholera toxin. Other mechanisms underlying the cholera secretion are discussed.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06469.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

In submaxillary sialoadenectomized and nephrectomized mice aggressive behaviour provoked 5 to 40‐fold increases in plasma renin concentration. The changes in renin concentration with time were different in different groups of confronted mice with only partial correlation between the pattern and the observable degree of fight. The changes were similar in sialoadenectomized mice with untouched kidneys as in sialoadenectomized and nephrectomized, indicating that aggression causes no measurable, if any, renal renin release. Repeated aggression with 2 hourly intervals provoked repeated renin relase from extrarenal and extrasubmaxillary sources. The renin concentrations of different organs showed the same mutual relationship as in other mammals, but were about 10‐fold higher. Splenectomy was without effect on the aggression‐provoked renin release. Antibodies against pure mouse renin neutralized the renin in plasma and organs, which contained only insignificant, if any, pepsin activatable inactive renin. Adrenaline, apomorphine, carbachol and dihydralazine were as isoprenaline and noradrenaline without effect on renin release in sialoadenectomized and nephrectomized

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06470.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Lipoprotein‐lipase (LPL) activity and intracellularly stored triglycerides were determined in muscle biopsies taken before and after an 85 km skiing race from 7 volunteers. The triglyceride stores were larger in slow twitch than in fast twitch fibres (proportions 5: 1 before the race). The LPL activity increased and the triglyceride stores in slow twitch fibres decreased during the race. The best trained subjects had the largest TG stores before the race and their TG stores also decreased most during the race. These subjects also had very small increases of LPL activity. The least trained subject on the other hand showed a 6‐fold increase of LPL activity. The high post‐race LPL activity in less trained subjects indicates a higher capacity for uptake of fatty acids from serum TG as compared to the more trained sub

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06471.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The effect of ingestion of amino acids (Vamin N), glucose, and fat (Intralipid) on the concentration of neurotensin‐like immunoreactivity (NTLI) in plasma was determined in 6 healthy male volunteers. After ingestion of Intralipid (55 ml, 200 mg·ml‐1) there was a significant increase in the plasma concentration of NTLI. The calculated integrated total NTLI response (6.7 ± 2.5 nM over 180 min) was statistically significant. Although isocaloric amounts of Vamin and glucose also increased the plasma concentration of NTLI, these increases were not statistically significant. The data indicate that fat is an important stimulus for the release of NTLI from the small intestine. It is suggested that neurotensin, or a metabolite, in blood may be a hormone involved in the postprandial inhibition of gastric motility and gastric acid secretion elicited from the small inte

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06472.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY