摘要:

AbstractPosition and velocity responses have been measured during the co‐activation of two indentified fusimotor fibres influencing the same primary or secondary ending in the ankle extensor or flexor muscles of the cat. The effect of double‐fibre activation has been compared with that of stimulating the participating single‐fibres in isolation. During the activation of a dynamic‐static combination complete ‘occlusion’ was usually encountered in the steady discharge at ‘zero’ extension, in the position sensitivity and in the velocity responses to length decrement. Larger responses than any of the two individual actions occurred in the response to dynamic length increment. In the dynamic‐dynamic and in many of the static‐static double‐activations the responses were indistinguishable from those of single‐fibre stimulation at higher stimulus frequency. Other static‐static combinations gave rise to ‘averaging’ of the two single‐fibre effects; this was seen in the position sensitivity and in the velocity responses particularly during static I—static II co‐activations. Possible modes of fusimotor inter

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1968.tb10920.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe postsynaptic effects evoked in lumbar motoneurones were studied following electrical stimulation of the brain stem in the cat. The spinal cord was transected at the lower thoracic level leaving only the ipsilateral ventral quadrant intact. With a stereotactical method a low threshold focus was found in the medial brain stem from which monosynaptic EPSPs could be evoked in flexor motoneurones. It is concluded that this effect is mediated by fibres descending in the ipsilateral medial longitudinal fascicle and it is tentatively suggested that these fibres originate from the ipsilateral upper medullary or lower pontine reticular formation. Monosynaptic EPSPs were also evoked in some extensor motoneurones from this medial brain stem region and at such a strength of stimulation that stimulus escape to the lateral vestibulospinal tract is excluded.

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1968.tb10921.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractPosition and velocity responses of spindle endings in the external intercostal muscle of the cat have been determined in the absence and in the presence of fusimotor fibre stimulation at a constant rate. The length input signal had triangular wave form. A close functional resemblance was found between intercostal and leg muscle spindles: primary and secondary endings could be separated among intercostal afferents with the same methods that have been used in leg muscles; dynamic and static fibres were discerned and the fusimotor effects on position and velocity sensitivity were the same as in the hind limb; the ratio between dynamic and static fibres was about 1: 3,i.e. the same as in the hind leg. Some dissimilarities existed: the number of ‘intermediate’ endings was larger in the intercostal than in the leg muscles; position and velocity sensitivities were generally larger in intercostal endings. These discrepancies are discussed. As a general conclusion it is stated that a spindle model elaborated from studies on leg spindles can easily be modified to account also for intercostal spindle behavi

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1968.tb10922.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe aim of the present investigation was to determine the transfer function between fusimotor stimulus rate and afferent impulse frequency of muscle spindles at constant length. Spindle endings in the external intercostal and in the ankle extensor and flexor muscles of the cat have been subjected to variations in fusimotor stimulation frequency. The variations had sinusoidal form and ranged in repetition rate from 1/4 to 1/12 c/s. Both single‐fibre and double‐fibre stimulations were studied. Linear static and dynamic input‐output relations were found in the stimulus frequency range 60 to 180 pulses/sec. For all combinations of one or two fusimotor fibres to one spindle ending the transfer function had the same general form. The static sensitivities were largest for primary endings under static fusimotor control; about the same sensitivities were obtained in dynamic fusimotor activation of primary endings and in static activation of secondary endings. With regard to dynamic properties all combinations of fusimotor fibres and spindle endings were equivalent. This was further tested with step and triangular wave inputs. Explanations for this similarity are disc

ISSN:0001-6772    

DOI:10.1111/j.1365-201X.1968.tb10923.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe effect of tetanization, using both indirect and direct stimulation, on the twitch response to post‐tetanic single shocks and on the tension response to a second tetanization has been studied in the gastrocnemius, soleus and extensor carpi radialis longus (ECFU) muscles of kittens ranging in age from 3–140 days, and in adult cats. Direct stimulation was applied in completely curarized animals. Nembutal® anaesthesia was used.Equal tension was found to be produced by a first tetanization and a second one, the latter elicited during the period of twitch potentiation following the first. The second tetanization was, however, found to give a steeper rise in tension than the first.In each animal, the maximal post‐tetanic potentiation (PTP) of twitch tension obtained was of about equal magnitude following tetanization by indirect and direct stirnulation. In newborn kittens, practically no PTP occurred in the gastrocnemius, whereas in the soleus there was a PTP of about 50 %. With age, the PTP produced by direct stimulation was found to increase in the gastrocnemius and decrease in the soleus, as after stimulation through the motor nerve. The time course of the effects produced by the two types of stimulation was also similar. After tetanization by both types of stimulation, potentiated twitches showed a steeper rise in tension than pre‐tetanic control twitches, and in the gastrocnemius they also showed, a marked lengthening of half relaxation time. In the kitten soleus, little change took place in the latter. Non‐potentiated twitches of adult cat soleus muscle showed shortening of contraction and half relaxation time.It is concluded that the main mechanism of twitch potentiation in the neuromuscular system of kittens and cats is located within the mus

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1968.tb04239.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractGastrin activity was determined in sections, cut parallel to the surface, of the antral mucosa and submucosa of cats and dogs and in the aboral corpus mucosa of dogs and man. The maximal gastrin activity in the antrum was found in the basal 2/3 of the gland crypt region of the mucosa. The superficial 1/3 of the antral mucosa of the cat contained no gastrin activity, whereas in the dog traces of activity were found in this part of the mucosa. Extracts from the submucosa of the cat antrum contained no gastrin activity, but in the submucosa of 1 dog out of 3 low activity was found. The results suggest that the gastrin cells are localized predominantly in the region of the middle and basal parts of the gland crypts of the antral mucosa in the dog and cat. In the corpus mucosa immediately oral to the visualized antrum‐corpus boundary, no gastrin activity was found in 3 dogs and activity was present in only 4 of 14 doudenal ulcer patients. Thus the gastrin cells do not seem to be present in the corpus mucosa of dog or man, but the occasional finding of gastrin activity in the most aboral part of the acid secreting gastric mucosa of man speaks in favour of a dentate, or sometimes notchy, antrum‐corpus bound

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1968.tb04240.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe overlap between projections of visual, auditory, cutaneous and muscle afferents to the cerebral cortex of the anterior suprasylvian sulcus was studied in cats anesthetized with chloralose. The visual projections were found near the junction between the anterior and the middle suprasylvian sulcus. They overlapped in rostral direction with the auditory projection area in the lower bank of the anterior sulcus. The overlap was, however, not complete and large click potentials, but no response to a light flash, were recorded in the lower bank just caudal to the locus of the Group I muscle afferents. Low threshold cutaneous and high threshold muscle afferents from the neck projected to the anterior suprasylvian and ecto‐sylvian gyri and to the upper bank of the anterior suprasylvian sulcus. Low threshold rnuscle and cutaneous neck afferents projected to the postcruciate dimple. A hypothesis concerning the function of this cortical region is discusse

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1968.tb04241.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractContractions of the pilomotor muscles of individual carpal tactile sinus hairs in the cat were studied by simultaneous recording of the movement of a single hair by means of a capacitance meter, and of the electrical activity during the muscle contraction, as recorded by an external metal microelectrode. Single shock stimulation of the nerve gave rise to a twitch contraction, whereas repetitive stimulation caused aummation of contractions at frequencies higher than 0.2/sec and fusion at frequencies of l/sec or more. The electrical response consisted of a slow potential and a superimposed spike. These components were both shown to be dependent on the stimulus strength and to be facilitated on repetitive stimulation. 4t stimulus frequencies higher than 3/sec the spike gradually declined in amplitude and was substituted by a rhythmic oscillation at the same rate as the stimulus. Even when no spike was recorded the contraction was sustained. Comparisons are made between the electrical activity elicited in the pilomotor muscles and the junction potentials and spikes recorded in other types of smooth muscle.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1968.tb04242.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractMucosal specimens from different parts of the gastro‐intestinal tract of cats were extracted for gastrin according to the method of Komarov. Extracts were also prepared from the mucosa of the antrum and proximal duodenum according to a modification of a method of Gregory and Tracy. The extracts were assayed for gastrin activity on nonanesthetized gastric fistula cats. Gastrin‐like activity was found in the mucosa of the antrum and the proximal duodenum using either method of extraction. Gastrin‐like activity was also found in most extracts from the cardiac region of the stomach. The gastrin‐like activity of the extracts from the cardiac region and the proximal duodenum was 5–10 per cent of the antral activity. No gastrin‐like activity was detected in the acid secreting part of the stomach, in the middle and distal parts of the duodenum, in the jejunum, colon

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1968.tb04243.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractRats were intraperitoneally injected with 1 × 50 mg and 3 × 50 mg of Triton WR‐1339. There occurred steep increase in esterified fatty acids and cholesterol, and the plasma proteins decreased. The mucosal mast cell count and the metachromatic granulation of these cells increased, after a primary decline, in the gastric and jejunal walls under the effect of Triton. The bearing of the phenomenon on hyperlipaemia is considered in the discussion, bringing up the potential inhibition of heparin rele

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1968.tb04244.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY