摘要:

Cerebral blood flow was measured with the14C‐ethanol technique in 8 regions (frontal, parieto‐temporal and occipital cortex, caudate nucleus, thalamus, cerebellum, mesencephalon, and pons) of rats. The highest flow values (83–89.5 ml/100 g/min) were found in cortical areas, whereas pons had the lowest flow (48 ml/100 g/min). Intravenous infusion of noradrenaline or adrenaline markedly reduced rCBF (by 22–48% of control levels) in all regions except thalamus, mesencephalon, and pons. The noradrenaline‐induced reduction was blocked, and the effect of adrenaline reversed, after pretreatment with the alpha‐receptor antagonist, phentolamine. Isoprenaline infusion markedly augmented rCBF in thalamus, mesencephalon, pons, and also in the caudate nucleus. The response was reduced by the beta‐receptor antagonist, propranolol. The experiments show the presence and heterogenous distribution in the cerebrovascular bed of alpha‐and beta‐adrenoceptors that can be activated by sympathomimetics given systematically. If noradrenaline was allowed to pass the blood‐brain barrier after osmotic opening with urea, an increased regional flow was obtained, probably due to a mechanism where the vasodilator effect secondary to activation of cerebral metabolism predominated over the direct vasoconstrictor

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06478.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The inhibitory effects caused by volleys in cutaneous afferents on the transmission through some polysynaptic segmental pathways activated by high threshold muscle afferents were studied in chloralose anesthetized, spinal cats. Pathways studied were groups II and III to motoneurones as well as group II to primary afferents. The results suggested that two different mechanisms were involved. One mechanism, with a very slow time course (duration more than 400 ms), is suggested to be an example of presynaptic inhibition between different primary afferent systems. This mechanism required high threshold (≥ 1.6T) conditioning shocks, and appeared simultaneously with the component II dorsal root potential being evoked by the cutaneous afferent volley. The other mechanism, with a faster time course (duration always below 300 ms), was dependent upon low threshold (≥ 1.5T) cutaneous conditioning volleys. This inhibitory interaction could not be ascribed to the same presynaptic mechanism, but is suggested to be an example of postsynaptic inhibition at an interneuronal level. The presumed disynaptic excitatory pathway from group II muscle afferents to flexor motoneurones was not inhibited by cutaneous conditioning shocks, but could on the contrary be facilitated by activity in low threshold cutaneous afferents, probably at the only intemeurone involved in this group II path

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06479.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Segments of small mesenteric arteries (—150 μm lumen diameter) and of corresponding veins were taken from 5‐month‐old spontaneously hypertensive rats (SHR) and from age matched Wistar Kyoto (WKY) controls. The segments were mounted on a myograph which enabled their mechanical and morphological parameters to be investigated simultaneously. Compared with the WKY arteries the lumen diameter of the SHR arteries was smaller while the media thickness and active wall tension response were greater. On the other hand there were no differences between the corresponding veins from SHR and WKY animals although, compared with the arteries, the veins had a greater lumen diameter, a smaller media thickness and a smaller tension response. The findings suggest that the morphological and mechanical differences seen in arteries from SHR are not found on the venou

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06480.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Inbred Hooded Lister rats were immunized with egg albumin with B. pertussis vaccine used as an adjuvant. The serum levels of total IgE and IgE antibody (egg albumin specific) were determined by radioimmunoassay techniques before and after immunization. The basic level of total IgE in serum was 560 ± 110 ng/ml. After immunization a maximal peak at day 11 of 1940 ± 160 ng/ml was registered. Anti‐egg albumin IgE antibody showed a maximum around day 13 of 75 ± 11 units/ml. Pleural mast cells were isolated on Ficoll between day 14 and 20 after immunization. A significant negative correlation between the basic total IgE level and histamine release by antigen (egg albumin) was found and also a significant positive correlation of specific IgE antibody (determined at day 11) and histamine release. The correlation between IgE level and histamine release was slightly improved if instead the ratio of specific IgE antibody over total IgE was

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06481.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Histochemical muscle fibre composition was studied in biopsies from the four different muscles of the abdominal wall (rectus abdominis, RA, obliquus externus, OE, obliquus internus, OI, and transversus abdominis, Tr) in 13 normal human subjects (9 females and 4 males, age 24–55 years) undergoing gall‐bladder surgery. Muscle fibres were classified as Type I, II A, II B or II C on the basis of their myofibrillar ATPases' pH lability. There were large inter‐individual variations in fibre composition, whereas, in general, the differences between the different muscles were minor or non‐existent. Mean fibre distribution ranges were 55–58% I, 15–23% II A, 21–28% II B, and 0–1% II C fibres. The least fibre diameters were similar for all types and muscles (range of means 50–54 μm) except for Tr in which the Type II fibres were smaller (mean 45 μm). There was a high correlation in the size of Type I vs. II fibres and Type II A vs. II B fibres in all layers. The oxidative potential (NADH‐diaphorase staining intensity) appeared high in Type I fibres and low in Type II fibres, irrespective of subgroups. Thus, based on histochemical fibre composition, the different abdominal muscles appear to have a similar functional capacity. However, functional differences between individuals were indicated by the large inter‐individual variation in mu

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06482.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Efferent cervical vagal nerve stimulation in the cat caused a marked increase of the portal plasma 5‐HT concentration. This increase was more than two‐fold within 15 min of stimulation. After cessation of stimulation portal plasma 5‐HT returned to basal levels within 10 min. Treatment with the β‐adrenoceptor antagonist propranolol, in various doses (0.1–2 mg/kg b.wt.), did not abolish but significantly reduced the response to vagal stimulation, particularly during the final part of the stimulation period. The results confirm the existence of a β‐adrenoceptor‐mediated release of 5‐HT, but also suggest that other mechanisms for 5‐HT release may be involved in the response on vaga

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06483.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Effect of ethanol on adenosine 3′, 5′ cyclic monophosphate (cAMP), calcium (Ca) and magnesium (Mg) excretion was studied in controlled clinical conditions in man. Seven male volunteers served as their own controls. In 5 subjects cAMP excretion was primarily suppressed by ethanol. Ethanol appeared to have a biphasic effect on Ca excretion, an initial stimulation followed by a conservation phase. Mg excretion was stimulated by ethanol in 5 subjects. Subjects having nausea and vomitus and the most severe hangover symptoms had the lowest urinary Ca excretion and the lowest initial cAMP excretion. Ca and Mg metabolism and the susceptibility of the body to the toxic effects of ethanol appeared to be interrela

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06484.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The effects of conditioning vibrotactile stimulation of particular tactile receptor groups on thresholds to painful electric stimuli were studied in seven healthy adults. Preferentially Pacinian afferents were activated with conditioning sinusoidal vibration of 240 Hz at 20 and 200μm amplitudes and preferentially non‐Pacinian tactile fibers were activated with conditioning sinusoidal vibration of 20 Hz at 200 and 400 μm amplitudes. None of the subjects showed pain threshold elevation during activation of non‐Pacinian tactile fibers. However, 6 of the 7 subjects showed significant pain threshold elevation with conditioning vibratory stimulus of 240 Hz at 200 μm amplitude, and 4 subjects showed significantly elevated pain thresholds with conditioning stimulus of 240 Hz at 20 μm amplitude. It is concluded that the activation of Pacinian afferents causes inhibition of pain conducting p

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06485.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

A nerve membrane model with a two‐state pore system was investigated by computer simulation in the uniform (space‐clamped) case. Both sodium and potassium conducting pores were modelled, each pore having four independent gates which switched randomly between the open and the closed position, governed by the assumed rate constants. Each pore conducted only when all the gates were open. The model was based upon the Hodgkin‐Huxley equations for the giant axon in squid, and in the limit of an infinite number of pores it was identical to these. The firing behaviour of this model as a function of the number of pores and the injected current were investigated. The mean firing frequency and the distribution of interspike intervals were mainly used in the presentation of the results. It was found that for pore numbers less than about 20000 the main effects due to a finite number of pores were a lowering of the current threshold for firing and a more linear frequency current relationship relative to that of the original H‐H equations. For higher pore numbers an increase in the current threshold and a pronounced burst firing close to the threshold wer

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06486.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The aim of the present study was to elucidate in some detail the characteristics of the intrinsic basal vascular tone in the adrenergically blocked skeletal muscle with regard to its extent and site along the vascular bed, its dependence on arterial pressure via static and dynamic transmural pressure stimuli, and its sensitivity to local metabolic influence. Basal tone, which apparently is of myogenic nature, was pronounced in ‘proximal arterial vessels’ (>25 μm i.d.) and in the ‘microvessels’ (<25 μm), but low in ‘large veins’. Its functional characteristics, however, were different in the ‘proximal arterial vessels’ and the ‘microvessels’. Normal basal tone in the ‘microvessels’ thus seemed to be intimately dependent on the arterial blood pressure level and, at least partly, initiated by its static mean pressure distension effect as well as by its dynamic pulse pressure oscillations. It could be virtually abolished by a transmural pressure decrease applied at fast rate (‘strong inhibitory dynamic transmural pressure stimulus’). Basal tone in the ‘proximal arterial vessels’, on the other hand, was little affected by arterial pressure and almost irresponsive to transmural pressure stimuli. Basal tone in the ‘microvessels’ was much more sensitive to metabolic stimuli than that in the ‘proximal arterial vessels’. The present results, viewed in the light of some recent electrophysiological studies on vascular smooth muscle, suggest that smooth muscle in the ‘microvessels’ is mainly of the spike‐generating type, whereas that in the ‘proximal arterial vessels’ seems to be of differen

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1979.tb06487.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY