摘要:

AbstractThe spectral integration of single units in the rat's cochlear nucleus has been investigated by two different methods, namely1. by measuring the difference in sensitivity to broad band noise and to pure tones of a frequency equal to the unit's characteristic frequency (CF).2. by estimating the width of the tuning curve.The results show that the mean value of the width of the tuning curves increases with the CF of the units. The bandwidth at 3 dB above maximum sensitivity agrees with the mean value of the bandwidth estimated on the basis of the difference in threshold of tones and noise. Bandwidth values estimated on the basis of noise measurements 10 dB above the threshold, however, are smaller than those obtained on the basis of threshold values. The results thus indicate that the spectral resolution of single units in the rat cochlear nucleus above threshold is higher for broad band noise than the measurements with pure tones indicate (tuning curves). The time patterns of the neural responses to noise and tone stimulation, judged from a dot display of the discharges, show no apparent difference except for units with a very low CF.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04665.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe temporal characteristics (system impulse response) of the peripheral, auditory spectrum analyzer, up to the level of the neural excitation, has been studied. This was accomplished by recording the average firing rate of single units in the rat cochlear nucleus in response to paired clicks in which the interval between clicks was varied over a large range. The results show that the system impulse response of all units studied was a damped oscillation. The frequency of the oscillation was equal to the characteristic frequency of the unit. On basis of these recorded responses the auto‐correlation of the system impulse response was computed. It was furthermore found that bandwidth values determined on the basis of the derived autocorrelation functions were smaller than those estimated from tuning curves and isorate curves. It is concluded that the auditory system of the rat has a higher spectral resolution in regards to double click stimulation than it has for stimulation with single pure tones. The study furthermore indicates that the sharpening of the spectral resolution of ‘the auditory system represented by unit responses in the rat cochlear nucleus is not accomplished by interactions between the time integrated output from a number of hair ce

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04666.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractUnitary nerve impulses originating from slowly adapting muscle receptors were recorded with percutaneously inserted tungsten electrodes from the median and the tibial nerves in awake human subjects. Discharges from 72 receptors located in the wrist flexor muscles and the ankle extensor muscles were analysed. The possibilities to derive criteria of muscle spindles and Golgi tendon organs were tested by means of a number of experimental procedures. A differentiation between these two types of receptors could, for technical reasons, not be achieved by electrically induced muscle twitches. For the majority of the endings muscle spindle characteristics could be demonstrated. In relaxed muscles, a number of the muscle spindle afferents exhibited a high dynamic sensitivity to passive joint movements whereas a smaller proportion of them had a low dynamic sensitivity. A steady state discharge as a function of the muscle length could be demonstrated for some of them. During weak voluntary contractions without external muscle shortening, the majority of the units responded with a sustained impulse discharge which started and stopped almost simultaneously with the onset and the cessation of the extrafusal contractions. It was concluded that the motor cortex exerts a very powerful control of the intrafusal muscle fibres of the majority of the muscle spindles. For a few units the relation between the muscle force and the impulse frequency was very striking but for the majority of them this relation was poor. It was concluded that the former units were Golgi tendon organs.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04667.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractIn addition to noradrenaline (about 1.3–1.5 μg/g) dopamine (about 0.2 μ/g) is present in the sympathetic chains of the cat and pig. By means of a recently developed microspectro‐fluorimetric method, the cellular localization of these two catecholamines has been studied. Dopamine was found in a special type of small, intensely fluorescent cells (“SIF‐cells”) located among the adrenergic ganglion cell bodies. Most of the dopamine present in the sympathetic ganglia is probably stored in

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04668.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe transport mechanism for chloride across the proximal tubular epithelia in the rat was investigated with a free‐flow micropuncture technique. The purpose of the investigation was to determine whether there is an active carrier system for chloride transport out of the tubule with different affinities for different halides and higher for iodide than for chloride. The TF/P values for sodium, potassium, chloride and iodide were determined simultaneously. The TF/P value for chloride (1.15) was significantly lower than the TF/P value for iodide (1.73). It was concluded that there is no evidence of an active transport system and that chloride and iodide are transported passively out of the tubular lumen, the permeability for iodide being somewhat lower than for chlorid

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04669.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe transport mechanism for chloride was studied in rat distal tubules with a free‐flow micro‐puncture technique. The tubular fluid to plasma concentration ratio (TF/P) was determined simultaneously for sodium, potassium, chloride and iodide. The experiments were designed to determine whether there is a common active carrier mechanism for halide transport out of the distal tubules with a higher affinity for iodide than for chloride. If such a transport system exists it should give rise to a lower TF/P value for iodide than for chloride. However, the TF/P value for iodide was 0.78 and was significantly higher than for chloride (0.39), a result which is interpreted to mean that no such active carrier transport mechanism for halides exists in the distal tubules. In our opinion the differences in TF/P values depended on a lower passive permeability for iodide than for chlor

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04670.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe diffusional water permeability in rat proximal tubules was studied in microperfusion experiments with triturated water. The perfusion solutions were chosen either to give no net flux or a net water flux in either direction. The diffusional water permeability at zero net water flux was 564. 10‐‐5cm/sec. The significance of the permeability measurements made during a net flux is discussed. The osmotic water permeability was 15. 10‐‐8cm3cm‐2sec‐1. (cm H2O)‐lThe large differences between osmotic water permeability and diffusional water permeability in zero net flux conditions cannot be accounted for entirely by an unstirred layer effect and are interpreted to mean that water transport along osmotic gradients is mainly a bulk flow through aqueous pores and not a diffusional flow and that the proximal tubular wall is a highly po

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04671.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractOsmotic and diffusional water permeability was studied in rat distal tubules in antidiuresis and water diuresis with a microperfusion technique. In antidiuresis the osmotic water permeability was 6.1 ± 1.2. 10‐‐8em3cm‐2sec‐1(cm H2O)‐land the diffusional water permeability 327 ± 132 10‐‐5cm/sec. In water diuresis obtained by hypophysectomy and water loading the osmotic water permeability was 1.6±1.6 10‐‐8cm3cm‐2sec‐1(cmH2O)‐1and the diffusional water permeability was 157±32 10‐‐5cm/sec, both values being significantly lower than in antidiuresis. The osmotic water permeability is much larger than the diffusional water permeability; this can only be partly accounted for by the existence of an unstirred layer and is supporting evidence for the concept of aqueous pores, through which the water moves down osmotic gradients mainly as bulk flow and not as a purely diffusional flow. The comparatively larger increase in osmotic water permeability than in diffusional water permeability in antidiuresis suggests that ADH can change the pore area‐pore diameter relation so that the bulk flow increase is larger than th

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04672.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractAs the interrelationship of autonomic patterns involving cortico‐hypothalamic and bulbar levels is of general interest, the interaction between the hypothalamic defence reaction and the homeostatic baroreceptor reflexes was explored in cats with respect to cardiac as well as vascular effects. The results suggest, in conformity with Hilton's observations (1963), that defence area stimulation suppresses the baroreceptor reflex inhibition of the heart. On the other hand, the baroreceptor influence on vasoconstrictor fibre discharge was largely the same, whether defence area stimulations were performed or not. This had important haemodynamic consequences, especially for muscle blood flow, since the reflex inhibition of regional constrictor fibre tone could greatly enhance the cholinergic vasodilatation. Therefore such a differentiated interaction between oppositely directed central and reflex autonomic mechanisms has the consequence that the baroreceptor reflexes, rather than damping the defence reaction, act insynergismwith it with respect to net haemodynamic effects; some further implications of this are dealt with in the subsequent paper (Kylstra and Lisander 1969

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04673.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractIn experiments on cats, the interaction between the oppositely directed hypothalamic defence reaction and the baroreceptor reflexes was analysed with particular regard to the effects on aortic blood flow, left ventricular work load and muscle blood flow. Because of their differentiated interaction — suppression of the baroreceptor reflex effect on the heart with preservation of the reflex modulation of the vascular bed (Djojosugitoet al. 1969) — the baroreceptor reflex so modifies the primary defence reaction, with its intense neurogenic drive on the heart, that a greater cardiac output is gained for a given left ventricular work load. This particularly favours muscle blood supply. It follows that such a differentiated interaction between two basically opposite autonomic patterns causes them to act in synergism with respect to efficient cardiovascular performance in states of emerge

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1970.tb04674.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY