摘要:

AbstractA device is described for the maintenance of a constant low air pressure. Rats were held under hypoxia equivalent to 1,000—8,000 m altitude for several months. Total hemoglobin was determined according to a modified alveolar CO‐method. Total hemoglobin at sea level was about 0.75 g/100 g body weight, increased significantly at 1,000 m and to 1.1 g at 4,000 m. A maximum of 2.2 g was at 6,000 m. The limit of survival was reached at 8,000 m. New levels of total hemoglobin was reached after 20 and 40 days at 5,000 respectively 6,000 m. An additional supply of iron had no effect. Hemoglobin per 100 ml. blood was 14, 19 and 26 g at sea level, 4,000 respectively 6,000 m. Hematocrite was 45 % at sea level, 60 % and 85 % at 4,000 m and 6,000 m respectively. Hemoglobin concentration parallels hematocrite values during hypoxia. Blood volume increased by 20—50 % at 6,000 m but plasma volume decreased by 10—20 %. Hemoglobin per unit body weight decreased with increasing body weight in animals adapted to 5,000 and 6,000 m, also the blood volume at 6,000 m. The daily production of hemoglobin was calculated from the total hemoglobin and the assumed life span of 60 days for erythrocytes. It increased to 4—5 times the normal during the first two days regardless of degree of hypoxia, but was thereafter a function of the degree o

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1963.tb02571.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractEight well trained athletes (cyclists) with large dimensions of the circulatory system were studied with heart catheterization at rest and during exercise at 800 and 1,600 kpm/min both while sitting and supine. The results are compared with data from non‐athletes. The cardiac output at rest and during work showed the same relation to the oxygen uptake as in nonathletes. The cardiac output was less in the sitting than in the supine position by 2.6 1/min at rest and 1.8 1/min during heavy work, due to a smaller stroke volume in the sitting position in both groups. On transition from rest to exercise the stroke volume increased 9 % in the supine and 48 % in the sitting position. After these initial changes the stroke volume remained constant during continued exercise with the heavier load in both body positions. The difference in stroke volume between supine and sitting position averaged 43 ml at rest and 9 ml during heavy exercise. The stroke volume during work in the supine position showed the same relation to the blood volume as in the nonathletes. The stroke volume was larger than expected from the size of the heart, when compared with the previously demonstrated relationship in nonathletes. The rate of work, performed at pulse rate 170, bore approximately the same relationship to the stroke volume during exercise in both groups. The larger oxygen transport capacity of these athletes as compared to nonathletes is explained by a larger stroke volume. During exercise the ventricular filling pressures were higher than in nonathlete

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1963.tb02572.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractThe influence of Vitamin D on serum calcium levels cannot be explained by the effect on intestinal absorption of calcium alone. Rather, some alteration in the distribution of calcium between bone and the circulating fluids must occur, a concept that has received in‐direct experimental support. In the study reported below bone (calvaria from mice) was incubatedin vitrountil a steady‐state equilibrium for calcium and phosphorus between the bone and the incubating fluid was reached, thus at the end of the incubation simulating the situationin vivo. The concentrations of these ions that bone from animals pre‐treated with Vitamin D maintained in their surrounding fluids were significantly higher than Vitamin D deficient controls demonstrating directly the calcium‐mobilizing effect of the vitamin. Further, Vitamin D increased the passive solubility of the bone mineral and lactate production by bone cells, suggesting modifications of bone cell metabolism. In the absence of Vitamin D, parathyroid hormone had the same effects as reported for the vitamin, indicating that the function of parathyroid hormone is independent of the presence of Vitamin D. Some evidence is presented that in mice deprived of Vitamin D secondary hyperparathyroidism

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1963.tb02573.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractIn 9 healthy, adult males the work intensity at pulse rate 170 (PWC170) was determined before and after i. m. injection of 0.75 mg methylscopolaminenitrate (MSN). The PWC170decreased 14 % after MSN. In 15 patients with normal circulation the effect of MSN was studied with heart catheterization at rest and during work at two progressive loads in the supine position. At rest the heart rate increased 66 %, the stroke volume decreased 34 %, and the cardiac output was unchanged. The ventricular filling pressures decreased. During work, performed after MSN, ventricular filling pressures and stroke volume increased progressively. At the highest work load the stroke volume was only 12 % lower than before MSN. Oxygen uptake, cardiac output, central blood volume and vascular resistances in the systemic and pulmonary circulations were unchanged after MSN, both at rest and during work. After MSN the heart volume, determined in the prone position, tended to decrease. The duration of the mechanical diastole, as measured from the phonocardiogram, was significantly shorter after MSN both at rest and during exercise. The investigation elucidates the relationship between the size of the stroke volume and the capacity for work at a given pulse rate and also between the size of the stroke volume and ventricular filling pressure.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1963.tb02574.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractAfter both unilateral and bilateral lesions in globus pallidus conditioned avoidance responses were extinguished more rapidly than in normal and control operated cats. This was observed at a time when retention had returned to normal. Animals with bilateral lesions in globus pallidus tested 30 days after the operation learned the avoidance response slower than normal and control operated cats. Retention tested 30 days after bilateral lesions in globus pallidus was impaired as compared with normal and control operated cats. Sixty days postoperatively retention was normal. Therefore a memory defect cannot account for the rapid extinction observed more than 60 days postoperatively; it may be explained by diminished fear.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1963.tb02575.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractRats were submitted to hypoxia corresponding to 6,000 m altitude. The effect on hemoglobin concentration, hematocrite, plasma protein concentration, total hemoglobin and the specific activity of the erythrocytes, tagged in vivo with Ci14‐2‐glycine has been studied during the first two days. The hemoglobin and plasma protein concentrations increased significantly. They were significantly correlated to each other. There is no indication that the spleen should act as a blood reservoir during these circumstances. The specific activity of hemin was unchanged, which indicates that no essential hemolysis or increase of the circulating hemoglobin occurred. However, the total hemoglobin increased significantly. Thus the amount of hemoglobin in the erythropoietically active tissues must have increa

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1963.tb02576.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractThe circulatory response in the “diving reflex” as indicated by changes in heart rate of unanesthetized ducks was found to depend on more than the asphyxia of submersion. “Diving” bradycardia was found to result from at least three factors; these were:I. A specific nervous reflex, resulting from submersion of the head. This first factor is the permissive and necessary factor for establishing the “diving reflex”, but it is strongly reinforced by at least two other mechanisms.II. The progressive hypercapnia during the asphyxia.III. The increasing anoxia during the asphyxia.The interrelationships of these three factors are briefly discussed. Stimulation of an area in the mesencephalon in many respects closely resembles the specific, central permissive factor needed for the “diving reflex”.A second area, in the diencephalon, was found from which cholinergic vasodilator fibers to the muscle vascular bed cou

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1963.tb02577.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractIn experiments on bovine mesenteric arteries under anaerobic conditions tone‐promoting drugs gave rise to contraction and to augmentation of the lactic acid production. Under certain experimental conditions it was possible to dissociate these effects. In the presence of glucose, dihydroergotamine selectively inhibited the contractile effect of adrenaline without influencing its stimulatory effect on lactic acid production. Replacement of the Tyrode solution with 6 per cent dextran solution resulted in selective inhibition of the contractile effects of adrenaline and histamine but did not interfere with the stimulation of the lactic acid production. Potassium ions selectively stimulated the contractile process, while the lactic acid production diminished during the contraction phaseper se. On substrate‐depleted arterial muscle, potassium ions had a more pronounced stimulatory effect than did adrenaline, histamine or barium ions. It is assumed that, despite the correlation of the contractile effects of tone‐promoting drugs to the stimulation of lactic acid production, these two factors are activated by separate mecha

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1963.tb02578.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractThe question as to whether smooth muscle contraction is accompanied by intensified glycogenolysis was studied in experiments on rabbit gut, on bovine tracheal muscle, and on mesenteric artery. Under aerobic conditions electrical stimulation augmented the glycogenolysis in these types of smooth muscle. Of tonus‐increasing drugs, only carbacholine enhanced glycogen breakdown in tracheal muscle. Under anaerobic conditions contraction of smooth muscle was not accompanied by glycogenolysis, despite the fact that lactic acid production was increased. Smooth muscle contraction, therefore, was not consistently associated with increased glycogen breakdown. In this respect there seems to be a difference between smooth muscle and striated muscl

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1963.tb02579.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractIn experiments on isolated stomach muscle from rabbit in Krebs‐Henseleit bicarbonate buffer and on bovine mesenteric arteries in Tyrode solution, insulin stimulated the synthesis of glycogen but had no demonstrable effect on the lactic acid productio

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1963.tb02580.x

出版商:Blackwell Publishing Ltd    

年代:1963

数据来源: WILEY