摘要:

AbstractThe temperature dependence of lactate dehydrogenase (LDH) in brain, heart and skeletal muscle and of acetylcholinesterase (AChE) in brain tissue was investigated in a homeothermic animal (the guinea‐pig), a poikilothermic animal (the codfish) and a hibernator (the hedgehog). The temperature of maxmial LDH activity was higher in the tissues from the guinea‐pig than the other animals (Table I). Similar and more pronounced results were obtained for AChE (Table

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1969.tb04546.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe effect of 3‐min exposure to 5 G acting in the head to seat direction on arterial oxygen saturation (Sao2) and pH, inspiratory minute volume (VI), end‐tidal Pco2and heart rate was studied in 8 healthy subjects breathing 100 % oxygen and wearing anti‐G suits. During the first min Sao2remained unchanged. Thereafter it fell at varying rates in different subjects, the average reduction at the end of the exposure being 6 % (range 0–17 %). Mean VIshowed a rapid initial increase by 3 liters/min, remained thereafter essentially unchanged for approximately one min, and increased continuously during the last two min (average final increase 7 liters/min). There were considerable individual differences in the responses of VI. Arterial pH showed a small acidotic shift in all subjects but one (average decrease 0.04 pH units). Average end‐tidal Pco2fell by 7 mm Hg within the first min and remained then essentially unchanged during the following two min. The arterial oxygen desaturation is attributed to a reduced oxygen content of blood from alveoli with very low V/Q ratios. Individual variability in the responses of VI, end‐tidal Pco2arterial pH and Sao2is referred to differences in the G‐induced displace

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1969.tb04547.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe adrenergic activity to the stomach in cats anesthetized with chloralose was modified by electric stimulation of somatic afferent nerves. Electric stimulation of “somatic pressor” afferents promptly elicited inhibitory responses of stomach contractions which contractions were, in turn, dependent on cholinergic nervous activity. However, in the absence of such cholinergic activity, corresponding somatic afferent stimulation had only an insignificant effect on the stomach, despite a considerable myogenic activity, suggesting that the inhibitory adrenergic nervous mechanism preferentially operated by interfering with the cholinergic nervous activity.—Activation of “somatic depressor” afferents, on the other hand, suppressed the prevailing supply, if any, of adrenergic nervous activity to the stomach, which could result in augmentation of vagally induced gastric motor responses. Similar effects were obtained also after spinal cord transection indicating that the “somatic depressor” afferents made propriospinal reflex connections with the sympathetic outflow t

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1969.tb04548.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractNo adrenergic nerves were found in the transplantable islet‐cell tumour of the golden hamster studied in this investigation, but the tumour cells displayed an intense formaldehyde‐induced fluorescence. Chemically, not only were dopa, dopamine, and 5‐hydroxytryptamine found in the tumour, but also a hitherto unidentified substance capable of forming a fluorophore with formaldehyde. There is evidence that the fluorophore of this substance dominates in tumour cells and makes it impossible to register the presence of dopa, dopamine, and 5‐hydroxytryptamine in the microspectrograph. The fluorescence microscopic analyses of the endocrine pancreas of the tumour‐bearing animals did not reveal any differences from normal hamsters. Thus, these golden hamsters with an islet cell tumour should be of great importance in further studies aimed at understanding the biological significance of the monoamines in the hormone production, as there are two quite different insulin producing cell systems: the islets of Langerhans and the tumour cells. The islets of Langerhans contain no demonstrable amount of mono‐amines in the islet cells–in contrast to many mammalian species–but a rich supply of adrenergic nerves. The islet cell tumour contains a large concentration of monoamines in the tumour cells but no ad

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1969.tb04549.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractIn 20 young rabbits weighing between 1.0 and 2.0 kg, inulin space, albumin space and erythrocyte space were determined simultaneously in the bone marrow of the femur by use of inulin‐carboxyl‐14C,125I‐labelled homologous albumin and51Cr‐labelled autologous erythrocytes. The mean inulin space was 22.5 ml per 100 g tissue, the mean albumin space 18.8 ml and the mean erythrocyte space 3.2 ml. These results indicate that albumin passes the sinusoidal walls and is distributed throughout the extracellular space of the bone

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1969.tb04550.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractSystematic studies on the vascular smooth muscle responses to histamine and 5‐hydroxytryptamine, similar to those previously accomplished in jawless vertebrates and fish, were performed in amphibians (frogs, toads and salamanders). Both intact animals and artificially perfused preparations were studied. The effects were recorded as changes in systemic arterial blood pressure after intravascular administration of drugs or as changes in vascular resistance after introduction of drugs into the perfusion fluid during perfusion at constant flow rate. Responses to adrenaline, noradrenaline and acetylcholine were studied for comparison. The direct or indirect nature of actions produced by the different drugs were evaluated by means of pharmacological blocking agents. The outcome of the studies may be summarized as follows: Marked and specific inhibitory actions of 5‐hydroxytryptamine on vascular smooth muscle, manifest as vasodilatation, are present in all studied species, displaying a feature which has not been demonstrated in jawless vertebrates and fish. In addition, the blood vessels of some amphibians occasionally show a constrictor response to 5‐hydroxytryptamine. The nature of the latter response remains uncertain. Histamine apparently has but negligible influence on amphibian vascular smooth muscle. The inhibitory and stimulatory actions of adrenaline and noradrenaline and the stimulatory action of acetylcholine, pharmacological characteristics of vascular smooth muscle also in more primitive vertebrates, are retained in the amphibians, while the inhibitory action of acetylcholine, like the inhibitory action of 5‐hydroxytryptamine, appears as a new

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1969.tb04551.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractIn fifteen rabbits heniatopoiesis was stimulated by a grave phenylhydrazine anemia. When the hematopoietic activity was maximal as judged from the reticulocyte counts, 6 or 7 days after the first injection of phenylhydrazine, the left femur was perfused in situ through the nutrient artery by blood led through an extracorporal perfusion arrangement from the left carotid artery of the anesthetized animal. The blood flow, the nutrient artery perfusion pressure and the intramedullary venous pressure were recorded. The bone marrow blood flow was greater and varied less than in non‐anemic animals. The arterial vessels exhibited a weak ability to auto‐regulate flow and acetylcholine caused arterial dilatation showing that neither the grave anemia nor the great hematopoietic activity had brought about a maximal dilatation of the arterial vessels. The venous resistance to bone marrow blood flow was constantly small whereas it has previously been shown to vary greatly in non‐anemic an

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1969.tb04552.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractSympathetic, cholinergic kasodilatation in skeletal muscle was induced as orienting and conditional reflex responses in conscious dogs. A sound stimulus elicited an orienting reflex accompanied by an atropine‐sensitive vasodilatation in the skeletal muscles of the hind limb. Further, a tachycardia and a slight blood pressure rise were noticed. The orienting reflex response disappeared gradually on repetition of the sound stimulus. The same cardiovascular events were obtained as conditional reflexes to both electrical cutaneous stimulation and exercise on a treadmill. The conditional responses were not diminished if the conditional reflexes were reinforced by training. Graded conditional responses were obtained when the intensities of the unconditional stimuli were varied. The increase in blood flow to the hind limb following treadmill exercise was not influenced by atropine. Our findings indicate that the sympathetic vasodilator system is activated prior to situations when an increased muscle blood flow is suddenly required. The results also suggest that activation of the dilator nerves takes place not only in emotionally charged situations, such as the defence reaction, but also in anticipation of exercise when the emotional involvement is less prominen

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1969.tb04553.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractDorsal spinocerebellar tract neurones adequately activated by Ia afferents from the tibialias anterior (TA), extensor digitorum longus (EDL) or flexor digitorum longus (FDL) muscles are regularly inhibited by group I afferents from the gastrocnemius‐soleus (GS) nerve. The inhibition is maintained throughout the duration of GS nerve stimulation. During inhibition the irregularity of firing may be unchanged or moderately reduced. Correspondingly the serial dependency between neighbouring intervals may be unchanged or reduced. The inhibitory input usually caused a constant reduction in firing frequency at various levels of excitatory drive or occasionally a greater reduction at higher levels of excitatory drive. The latter effect was associated with increased regularity of firing and reduced serial dependency. Comparable inhibitory effects were obtained by repetitive stimulation of the contralateral somato sensory‐cortex. It is suggested that the inhibitory effects can be accounted for by post‐synaptic inhibitory mecha

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1969.tb04554.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractIt is shown that aldosterone in concentrations higher than 1.5 · 10–9M induces a moult in vitro, and that the moult is accompanied by characteristic changes in the potential and the short‐circuit current. The sequence of changes can be divided into four parts: the first constant period, the inhibition period, the spontaneous activation period and the second constant period. At a concentration of 7 · 10–7M aldosterone the inhibtion starts 2–4 hrs and the activation 4–7 hrs after the addition. Furthermore it has been shown that the short‐circuit current is higher in the second constant period as compared to the control skin half. During the spontaneous activation period the net sodium flux exceeds the short‐circuit current by 25 %. The changes in chloride flux and sodium efflux during the moulting cycle were rather small. Both the moult and the activation of the short‐circuit current were abolished by actinomycin D. A hypothesis which could explain the behavior during the moulting cycle and the activation of the sodium t

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1969.tb04555.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY