摘要:

AbstractElectric stimulation of proximal and terminal guinea pig ileum induced contractions which were mediated by stimulation of cholinergic neurons. After blocking β‐receptors, prejunctional α‐receptors mediating inhibition could be studied in these neurons. In proximal ileum the order of potencies of the following agonists was: clonidine (8)*

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06210.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe kinetics of erylhropoiesis in 5 6 month oldSalmo salarL. was correlated to 4 combinations of environmental PO2and pH/PCO2. Given single doses of55Fe at the start of continuous flow bioassays, the incorporation was examined in circulating red blood cells (RBC) by autoradiography on blood smears. The proportions of immature, labelled immature and labelled mature erythrocytes were calculated on samples taken at intervals up to 52 days. Compared to control fish kept at a PO2corresponding to 90% air saturation and pH PCO2at 7.6/8 pH units/mmHg, oxygen depletion to 50% air saturation stimulated the proliferation of RBC stem cells and enhanced RBC maturation.Ceteris paribus, sustained hypercapnia at a PCO2in the respiratory water raised to 23 mmHg (pH 7.1–7.2), stimulated proliferation but did not affect the output of mature RBC. Simultaneously lowered PO2and raised PCO2to the levels mentioned above obviously stressed the fish, as the effect of lowered PO2per sewas not manifested. Radioactivity was traced to all clecdophorelically separable protein fractions from RBC hemolysates. The relevance of blood physiological criteria for probing the fitness or well being of fish in environmental respiratory stress conditions has been discusse

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06211.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractHistamine infused intra‐arterially into artificially perfused, maximally dilated rat hindquarters markedly increased fluid filtration and CFC but had essentially no effect on the diffusion capacity to small molecules. Isoprenaline largely prevented the increase in fluid filtration and CFC if infused prior to the start of the histamine infusion and, if infused after the start of the histamine infusion, promptly reduced fluid filtration and CFC to near control levels. Additionally, it was noted that severe cooling of the perfusate also largely prevented the marked increase in fluid filtration and CFC by histamine. This antagonism of histamine induced increases in macromolecular permeability represents a direct action of isoprenaline on the microvascular membrane which effectively counteracts that of histamine. The data also suggest that the large pores created by histamine are different from the large pore through which macromolecules normally transverse the microvascular membrane, and that catecholamines may exert a regulatory function in the control of microvascular permeability to macromolecules in pathophysiological states associated with massive histamine releas

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06212.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractTemperature regulation in harp seal pups (Pagophilus groenlandicus) has been studied byin vivomeasurements of oxygen consumption, body temperatures andin vitrodeterminations of the thermal values of a fur sample. The experimental animals were restrained and exposed to natural weather conditions. Solar irradiance above 600 W/m (global radiation) caused hyperthermia. Computer simulations based on the thermal values of the fur indicated that heat dissipation from primarily the limbs is a prerequisite for avoiding hyperthermia under natural weather conditions. Further simulations showed that the lower critical temperature of a lean newborn harp seal pup with standard metabolism is only – 1oC while it is depressed to –59oC as the pup grows, aquire a 10 cm thick layer of blubber and the metabolism increases to 1.5 times standard. High metabolism and tolerance to low deep body temperatures (35oC) seems a prerequisite for thermal balance in the harp seal pup under cold conditi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06213.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractAdenosine markedly inhibits cyclic AMP accumulation in isolated fat cells, whereas inhibitory effects of adenosine on lipolysis have been difficult to demonstrate. The present study has been performed on isolated “perifused” fat cells where continuous monitoring of the lipolytic rate is possible and where modulating substances, such as adenosine, are not allowed to accumulate. Adenosine deaminase was ineffective as a lipolytic agent in perifused fat cells, suggesting no important background activity of adenosine in this system. Micromolar concentrations of adenosine inhibited lipolysis induced by noradrenaline (0.3‐1 μM) and theophylline (1 mM). Theophylline was an effective lipolytic agent also in perifused fat cells suggesting that antagonism of adenosine is not the major mode of action of this drug on fat

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06214.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe weight of the upper part of the trunk is partially transmitted to the pelvis via the vertebral column. If the muscle walls around the abdominal cavity are contracted, a high pressure can be generated within the cavity (>200 mmHg). The abdominal space can then transmit part of the weight to,e.g., the upper part of the body. Intra‐abdominal pressure recordings have been performed during locomotion and other natural movements with intragastric pressure recordings. With each step, there is a phasic variation in pressure, with its peak coinciding with that of the peak vertical force exerted by the leg against the ground. The peak values increase progressively with the speed of walking/running up to a mean of 38 mmHg and with trough values of 16 mmHg. The phasic variations with each step is due to a phasic activation of the abdominal muscles, with an EMG activity starting 50 ms or more before foot contact. If an extra load is put on the back, the posture changes and at the highest speed of running the pressure values are significantly higher than without this additional load. After a jump down from a moderate height of 0.4 m, the average increase is 89 mmHg and can often exceed 100 mmHg. These pressure changes are large and will presumably act to unload the spine under the prevailing biomechanical conditions and, in addition, there will no doubt be an effect on the circulatory syste

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06215.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe glycogen‐depletion method was used to investigate the motor supply to tenuissimus with respect to the presence of fastβaxons and to assess the total proportion of both fast and slow β‐innervated spindles in this muscle. In a first series of 5 expts., groups of motor axons with conduction velocities higher than 85 m/s were repetitively stimulated so as to produce glycogen depletion in the muscle fibres they innervated. The whole muscle was then quick‐frozen, serially cut, stained to demonstrate glycogen and examined for intrafusal glycogen depletion. Zones of glycogen depletion were found in 16 of the 46 examined spindles; they were most frequently located in the longest of the chain intrafusal muscle fibres. Since it is known that there are no purely fusimotor axons to tenuissimus with conduction velocities above 50 m/s, it was concluded that β axons are present among the fastest axons to this muscle. In a second series of 5 expts. as many motor axons as possible with conduction velocities above 60 m/s were stimulated. Zones of glycogen depletion were found in 19 of the 47 examined spindles. They affected chain fibres in about half of the instances and bag2fibres in the others. As this latter location is characteristic of slow dynamic β axons, it was concluded that both slow and fast β axons occur regularly in the motor supply to tenuissimus. β‐innervation is present in at least 40% of tenuissimus spindles with almost no convergence of fast and slow β axons onto th

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06216.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractEffects of PGG2, PGH2and the endoperoxide analogue, EPA, on bronchial and vascular smooth muscle were studiedin vivoandin vitro.In the cat PGG2, PGH2and particularly EPA proved potent stimulators of airway resistance, and they were all significantly more active than PGF2α. They also increased pulmonary vascular resistance but EPA alone was more active than PGF2α. In guinea pigs EPA was 90–190 times more active than PGF2αin increasing tracheal insufflation pressure. Human bronchi contracted in response to PGG2, PGH2and EPA. PGG2and PGH2were equiactive with PGF2αand EPA was more than 500 times as potent. PGG2and PGH2lowered systemic arterial blood pressure and increased heart rate in cats. They were as active or more active than PGE2. EPA, on the other hand, resembled PGF2αin producing biphasic changes of blood pressure and heart rate or decrease of blood pressure and bradycardia in guinea pig and cat. The results obtained in this study indicate that PGG2, PGH2and EPA are potent stimulators of bronchial and pulmonary vascular smooth muscle. The data are also consistent with the view that a significant proportion of effects resulting from prostaglandin generation in the lung is due to prostaglandin endoperoxides rather than primary prostagl

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06217.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe effect of supraspinal impulse activity upon the intra‐axonal transport of acetylcholine (ACh), AChesterase (AChE) and cholineacetyltransferase (CAT) in rat sciatic nerve has been studied. A decreased impulse activity was obtained by spinal cord transsection (SCT) in the thoracic region 18 h, 6 days or 20 days before killing the rats. An increased neuronal activity was obtained by exercising the rats in a commercial rodent treadmill a couple of hours per day for 14 days. The amounts of substances which had accumulated in the sciatic nerve segments relative to a nerve crush performed 12 or 18 h. earlier were used to calculate the intra‐axonal transport. The amounts of proximo‐distally transported ACh decreased markedly with time after the SCT, while the proximo‐distal transport of AChE‐activity increased. Physical exercise appeared to increase ACh‐transport. Thus, input to motor pericarya from supraspinal centres may regulate intra‐axonal transport from the cell body of motor neurons int

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06218.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractA transfer of (32P)‐labeled phosphoryl groups has been demonstrated to occur between prelabeled Ehrlich cells (donor cells) and glioma cells (acceptor cells). The Ehrlich cells were generally prelabeledin vivoby an intraabdominal injection of (32P)‐orthophosphate 24 hours prior to scarifice of the tumor‐bearing mice. In some experiments two injections of (14C)‐glucose were given to the animals in addition to the injection of (32P)‐orthophosphate prior to sacrifice. The prelabeled Ehrlich cells were mixed with the glioma cells, that were still attached to the culture plates, and incubation took placein vitro.Labeled (32P)‐phosphoryl (14C)‐serine was isolated from the glioma cells as well as from the Ehrlich cells. The32P/14C‐ratio of (32P)‐phosphoryl (14C)‐serine of the glioma cells (acceptor cells) was significantly higher than found for the Ehrlich cells (donor cells). This was indicative of an interactive mechanism between the cells partly due to binding of membrane fragments from the Ehrlich cells on to the surface of the glioma cells and partly due to a phosphoryl group transfer between the two types of cells. Interaction experiments with a plasma membrane fraction prepared from the prelabeled Ehrlich cells vis à vis the glioma cells clearly showed that the phosphoryl group transfer mechanism between the cells was dominating and only a minor part of the interaction was due to adhesion. This transphosphorylation reaction represents a new type of interaction between cells. It was not influenced by either adenosine 3′,5′‐monophosphate

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1978.tb06219.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY