摘要:

AbstractFusimotor activity has been assessed from the changes in the response of muscle spindle receptors to a linear stretch and release of the muscle at various levels of fusimotor drive. The background fusimotor activity of the spinal cat caused an increased dynamic responsiveness of primary endings of ankle flexor as well as the ankle extensor muscles. Further, dynamic activation of both flexor and extensor primary endings was observed during electrical stimulation of the ipsilateral saphenous and the contralateral lateral popliteal nerve. Definite signs of activity in static fusimotor neurones were not found in spinal preparations. The observations support the hypothesis of an independent control of the static and dynamic properties of primary endings of the muscle spindle. It is suggested that the activity in the dynamic fusimotor system largely is supported by dorsal root inflow, whereas the static fusimotor system mainly depends upon descending suprasegmental activation.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04060.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractIt is not known from which part of the central nervous system the adrenal medulla is activated in hypoglycemia. The question was investigated in animals with various parts of the central nervous system removed, and the adrenal response was compared with that of intact animals. The amounts of adrenaline and noradrenaline in adrenal effluent blood were determined fluorimetrically. Intact animals showed increased secretion rate of adrenaline and to a lesser degree of noradrenaline in response to hypoglycemia. Decerebrate animals were capable of activating their adrenal medulla during hypoglycemia while spinal animals did not increase the rate of secretion above the resting level. It is, therefore, concluded that sympathetic neurones situated in the brain stem caudal to the hypothalamus are capable of activating the adrenal medulla in hypoglycemia. It proved very difficult to lower the blood glucose concentration in decerebrate animals despite the administration of large doses of insulin. The mechanism behind the insulin resistance of the decerebrate animal is discussed.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04061.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractTwo previous known methods to indicate blood‐brain barrier alterations—intravital dye tests and EEG test after drug activation—were applied in parallel in 25 short‐or long‐term experiments on cold‐induced cerebral lesions in the rabbit. The method of cold application was a modification of that of Hass and Taylor, supplemented by a recording of the extradural temperature. A new type of permanent electrode for EEG recording is described. In 19 of 20 animals in which a structure‐deranging lesion was induced, a concomitant blood‐brain barrier alteration could be demonstrated. In 11 of these 19 expts. a complete correlation of the two methods of barrier indication was obtained (8 animals inconsistent results). In 6 animals in which no blood‐brain barrier alteration was induced a concordance of negative results with the two methods was also seen. Three to four days was the maximum duration of blood‐brain barrier damage noted among the 13 animals in which the tendency to restitution of barrier function was studied. The results are in conformity with those of previous investigators and seem to justify the use of normally‐barred EEG activating drugs such as penicillin, as detectors of blood‐brain barrier alteration. These drugs seem particularly suitable for iterative st

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04062.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractFusimotor activity has been assessed from changes in the response of muscle spindle receptors. There was very little background fusimotor activity to the anterior tibial muscle in the decerebrate cat. To the ankle extensor muscles of the same preparations, appreciable dynamic as well as static fusimotor effects were observed. During stimulation of various spinal nerves, fusimotor activation was more pronounced to ankle extensor than to the flexor muscle. The flexor fusimotor effects could almost exclusively be ascribed to the static fusimotor system. A release of dynamic fusimotor activity to the flexor muscle occurred after section of the spinal cord in the lower thoracic region. The observations are discussed in terms of independent control of static and dynamic fusimotor systems.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04063.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractThe effect of light and moderate exercise (400, 625, and 700 kpm/min) on the alveolar‐arterial O2tension difference (A—aD) in the sitting position was studied in healthy, young adults by comparing the mean alveolar and arterial gas tensions determined over a 3 min rest period and over the ensuing 5th and 6th min of exercise. Arterial gas tensions were obtained from continuous measurements of arterial pH, oxygen saturation, and temperature. Alveolar O2tension was calculated by the alveolar gas equation, substituting arterial for alveolar CO2. At all three levels of exercise the arterial PO2increased significantly by about 5mm Hg. In the experiments at 625 kpm/min, in which the respiratory exchange ratio (R) was also determined, A–aD decreased from a mean value of 14.7 mm Hg at rest, to 11.0 mm Hg during exercise. In the experiments at 400 and 700 kpm/min, where no ventilatory measurements were made in order to avoid interference with free respiration, it was found that, for the range of possible R values, the A–aD remained unchanged or decreased during exercise. The arterial O2deficit,i. e.the difference in O2content between pulmonary end‐capillary blood and systemic arterial blood, was calculated to decrease from a mean value of 0.27 vol‐% O2at rest, to 0.18–0.22 vol‐% O2during exercise. Likewise, the calculated total venous admixture to the systemic blood flow decreased from a mean value of 4.7 per cent of cardiac output at rest, to 1.7–1.8 per cent of cardiac output during exercise. All the above changes are ascribed mainly to a reduction of the virtual shunt created by uneven distribution of alveolar ventilation to pulmonary cap

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04064.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractAntigen, glycogen, n‐decylamine and phospholipase A were shown to cause simultaneous release of 5‐hydroxytryptamine (5‐HT) and histamine from rabbit plateletsin vitro.There was no significant difference between the percentual release of 5‐HT and histamine. The release of 5‐HT was studied in greater detail. Release by antigen and glycogen both required the presence of plasma, occurred at similar rates and showed distinct temperature optima around 37° C. Heating the platelets to 47° C or plasma to 56° C produced an irreversible inhibition of such release. Heparin, EDTA, salicylaldoxime and the enzyme blocking agents ninhydrin (NHagroup inhibitor) and allicin (SH group inhibitor) inhibited release. Reduced glutathione reversed the action of allicin. High concentrations of sodium chloride blocked antigen‐induced release, but did not significantly reduce release by glycogen. The results are considered to support the hypothesis that antigen and glycogen release 5‐HT and histamine from rabbit platelets by the activation of similar release mechanisms and that enzymatic processes could be involved. Release of 5‐HT by n‐decylamine and phospholipase A did not require the presence of plasma and could not be inhibited by treatments or agents found to inhibit or reduce release by antigen or glycogen. The mechanism by which n‐decylamine and phospholipase A cause 5‐HT and histamine release from rabbit platelets is considered to differ from that

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04065.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractThe activities of nine different enzymes (glucose‐6‐phosphatase, combined activities of glucose‐6‐phosphate dehydrogenase and 6‐phosphogluconate dehydrogenase, phosphohexose isomerase, aldolase, iso‐citric dehydrogenase, lactic dehydrogenase, glutamic‐oxalacetic transaminase, glutamic‐pyruvic transaminase and glutamic acid dehydrogenase) were measured in liver, skeletal muscle, cerebral cortex, hypothalamus, adrenal cortex and thyroid gland of hypophysectomized rats and rabbits. The water and fat contents were determined in liver and muscle. DNA and protein were measured in all tissues. After hypophysectomy the activities of the Embden‐Meyerhof enzymes were unaffected when the values were expressed per unit wet weight or per unit protein. When calculated on unit DNA the activities of almost all enzymes were in most tissues significantly decreased after hypophysectomy. This finding is due to the fact that except for cerebral cortex and hypothalamus in rabbits the DNA content of all tissues studied is significantly increased after hypophysectomy. The observed changes in enzyme activities and DNA content in the tissues are discussed in relation to hormonal and dietary influences on

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04066.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractThe proportion of the total heat production of herons and gulls which at ambient temperatures ranging from—10° C to 35° C is dissipated to cold water or air surrounding their legs has been measured. At low ambient temperatures less than 10 % of the metabolic heat is lost from the legs. At higher ambient temperatures an increasing proportion of the metabolic heat is lost from the legs and at 35° C almost the entire heat production is dissipated through the legs. Heat loss to water was found to be about four times higher than to air of the same temperature. The degree of heat loss from the legs was shown to react within seconds to changes in ambient temperature. Likewise, panting stopped immediately when the legs were irregated by cold water. It is concluded that the naked legs of these birds serve as controlled heat conduits of great importance in thermoregula

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04067.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractA conspicuous bradycardia and a series of characteristic changes in the electrocardiogram (ECG) may be observed when diving vertebrates submerge. The ECG‐changes include prolongation of the P—R interval with ultimate disappearance of the P‐wave, and an elevated and peaked T‐wave. These deviations from the normal ECG‐pattern indicate severe hyperpotassemia. It is reported in the present paper that the plasma potassium concentration actually do increase during prolonged underwater exposure. The relationship between the ECG‐changes observed during submersion and the hyperpotassemia i

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04068.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractA telemetering device is described to record action potentials from muscles of the upper arm and the shoulder during the arm swing of natural walking. The forward swing is caused by activity in some inward rotators, the flexors remaining inactive. The posterior part of the deltoid and some outward rotators are responsible for the backward swing. During walk‐turning electrical activity occurred in flexors inactive during straight walking accounting for the increased excursion of the forward swing which counteracts the torsional movement of the trunk. Step‐related muscular activity persisted even when the arm was prevented from swing

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1965.tb04069.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY