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2. Measurements were made of the surface tension characteristics of lung extracts and of the liquid present in foetal lungs. These values were used together with gestational age and crown-rump length to designate the foetal lambs into mature and immature groups.
3. Lymph flow from the lungs averaged 0·99 ml./kg body wt./hr in immature foetal lambs, and 1·81 ml./kg/hr in mature foetal lambs before the start of ventilation. Lymph flow from the lungs of spontaneously delivered new-born lambs (mean age 51 hr) averaged 0·86 ml./kg/hr. In adult ewes right lymph duct flow averaged 0·11 ml./kg/hr and total lung lymph flow was estimated indirectly to be 0·33 ml./kg/hr. Calculated rates of protein flow in lung lymph (flow × protein concentration) were greater in foetal lambs than in adult sheep.
4. Total thoracic duct flow averaged 2·48 ml./kg/hr in immature foetal lambs, 5·30 ml./kg/hr in mature foetal lambs, 3·65 ml./kg/hr in new-born lambs, and 2·92 ml./kg/hr in adult ewes.
5. At the start of ventilation there was an increase in lymph flow from the lungs, which at 15-30 min reached a mean of 6·4 ml./kg/hr in mature lambs and 2·6 ml./kg/hr in immature lambs. At the same time the protein concentration of lymph decreased but the calculated protein flow increased.
6. The lungs of foetal lambs weighed more than the lungs of spontaneously delivered new-born lambs, and the difference could be accounted for by liquid which could be aspirated through the trachea of the foetal lamb. On ventilation of the lungs for 2 hr, without first allowing the escape of any lung liquid, lung weight measurements indicated that about 66% of the lung liquid had been taken up in mature lambs and about 50% in immature lambs.
7. It was concluded that the rate at which lymph is formed in the lungs is greater per kilogram body weight in foetal than in new-born lambs and greater in them than in ewes. The increase in lymph flow at the start of ventilation could account for the removal of about 40% of the liquid present in the lungs of the mature foetus and about 25% of the liquid in the lungs of the immature foetus.
相似文献2. The velocity of flow when anaesthetized varied from 0·1-2·0 cm/sec, to 5·0 cm/sec when conscious.
3. The pattern of flow was affected by respiration and the cardiac cycle. Most movement occurred at the end of inspiration.
4. The duct of five autopsy preparations was perfused with saline to assess the volume and velocity of flow produced by the level of pressure gradients previously observed in the duct. These studies show that the small gradients (2-5 mmHg) observed during life are more than sufficient to produce the normal volume and velocity of flow measured. The mean resistance of the duct was 0·5 mmHg/ml. min.
相似文献2. Values for red blood cells and albumin distribution spaces were 5·2 ± 0·6 and 20·2 ± 1·0 ml./100 g tissue, respectively, in the whole kidney. The ratio of tissue haematocrit over simultaneous arterial haematocrit averaged 0·56. The extravascular albumin fraction amounted to about 31·0% of the total albumin in the whole kidney.
3. A statistically significant correlation was demonstrated between osmotic urine/plasma (U/P) ratios (within the approximate limits of 0·6-1·8) and quantities of extravascular albumin in the medulla.
相似文献2. The output of total esterified fatty acid in intestinal and hepatic lymph in the unfed calf after recovery from the anaesthetic was about 0·6 and 0·025 g/hr, respectively.
3. Three lipoprotein fractions were obtained by ultracentrifugation of intestinal lymph samples. These appeared to correspond to very low- (d < 1·005), low- (1·2 > d < 1·005) and high- (d = 1·20) density lipoprotein of human serum. These lipoproteins contained approximately 40%, 50% and 10% respectively of the total lipid.
4. Very low-density lipoprotein was not found in blood serum or hepatic lymph and it was evident that very low-density lipoprotein and most of the low-density lipoprotein in intestinal lymph were derived from sources other than the capillary filtrate.
5. The output of total esterified fatty acid in intestinal lymph fell steadily during the course of an 11-16 hr period of bile deprivation to values 55% of those in comparable calves without bile fistulae. This was accompanied by a virtual disappearance of very low-density lipoprotein and a decrease in low-density lipoprotein of approximately 50%. These effects could not be attributed to starvation.
6. There was a general resemblance in fatty-acid composition between biliary lipid and the triglyceride of the lipoproteins, the predominant fatty acids being 16:0 and 18:1. The presence of appreciable levels of odd carbon number and branched-chain fatty acids were consistent with the transfer of significant amounts of free fatty acid from maternal blood to the foetus.
7. It is concluded that most of the lipid in thoracic-duct lymph of unfed, new-born calves is derived from the intestines and that the fatty acids of the very low-density lipoprotein in intestinal lymph arise from the absorption of biliary phospholipid.
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2. Intramuscular injections of vasopressin increased the rate of water uptake from distilled water. There was a good relation between doses and responses over various time intervals. A dose of 4 m-u. vasopressin/g body wt. doubled the rate of water uptake over a period of 1 hr. The same dose of vasopressin doubled the rate of water uptake when the toads were kept in solutions of sucrose or urea of different osmolarity.
3. The rate of water uptake when the toads were bathed in sodium chloride solutions was consistently 8 μl./cm2/hr greater than when bathed in sucrose or urea solutions of equal osmolarity. There was no water uptake when the sodium chloride solution was 285 m-osmolar.
4. Vasopressin (4 m-u./g) injected intramuscularly doubled the rate of water uptake from sodium chloride solutions of different osmolarity.
5. With solutions of potassium chloride, sodium nitrate, and potassium nitrate, in concentrations up to 150 m-osmoles/l., the rate of water uptake was found to be the same as with solutions of sodium chloride of the same osmolarity. Similarly, it was doubled by injection of vasopressin (4m-u./g).
6. The effect of temperature on the rate of water uptake before and after injection of vasopressin was investigated in toads kept in distilled water, sucrose, or sodium chloride solutions. For temperatures between 20 and 37° C, vasopressin (4 m-u./g) reduced the activation energy involved in the process of water uptake by 4000 cal.
7. The results agree with the view that water uptake follows a diffusion process which is facilitated by vasopressin, possibly as a result of increasing the size or number of available pores.
相似文献2. Alterations of blood volume caused inverse changes of angiotensin concentration owing to changes in the rate of generation of angiotensin which are probably due to changes of the rate of renin secretion.
3. Haemorrhage of 14-26 ml. blood/kg caused an increase of 0·25-1·5 μg/min in the rate of generation and an increase of 0·1-0·33 ng/ml. in the blood concentration of angiotensin.
4. The changes of angiotensin generation rate were not due to changes of renal arterial or venous pressure. They were abolished by blocking the renal nerves with lignocaine; they showed a consistent inverse correlation with central venous pressure but not with systemic arterial pressure.
5. It is concluded that changes of blood volume bring about changes of the rate of generation of angiotensin by a reflex mechanism the efferent limb of which involves the renal nerves. The afferent pathway remains to be elucidated, but the systemic baroceptors do not appear to be of primary importance.
6. The renin-angiotensin system is important in the homeostatic response to changes of blood volume.
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2. During noradrenaline infusion the mean blood flow through brown adipose tissue increased from 87 to 360 ml./100 g tissue (wet wt.).min, and the mean rate of oxygen consumption of brown adipose tissue rose from 9·3 to 60 ml. O2/100 g tissue.min.
3. During cold exposure the mean blood flow through brown adipose tissue increased from 90 to 304 ml./100 g tissue.min.
4. The mean cardiac output was 266 ml./kg body weight.min; during noradrenaline infusion it was 405 ml./kg body weight.min. At rest about one tenth, and during noradrenaline infusion about one quarter of the cardiac output went to brown adipose tissue.
5. It was calculated that most of the extra oxygen consumed during the metabolic response of the anaesthetized new-born rabbit to noradrenaline infusion or cold exposure was consumed by brown adipose tissue.
6. Hypoxia (breathing 10% O2 in N2) greatly reduced the increase in oxygen consumption but not the increase in blood flow in brown adipose tissue caused by noradrenaline infusion.
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2. The stress on the circulation was greater than when parts below the iliac crests were similarly exposed. Heart rate increased by 15-20 beats/min, there was a sustained fall in arterial blood pressure, and forearm blood flow fell profoundly and in some subjects was reduced to below 0·1 ml./100 ml. min.
3. In arms that were sympathectomized, or had received an intraarterial infusion of an adrenergic blocking drug, the fall in forearm blood flow was much less and could be related to the fall in arterial pressure.
4. When the suction was released there was a brief overshoot of arterial blood pressure and brief cardiac slowing. Forearm blood flow rose to reach a peak some 15 sec after the release.
5. In the sympathectomized forearm on release of suction there was an immediate rise in blood flow which was proportionately much greater than the rise in arterial blood pressure.
6. This rise was not due to circulating vasodilator substances or to the activity of cholinergic vasodilator nerves. The possibility that it was the result of a change in the tone of the resistance vessels occurring in response to the sudden change in transmural pressure is discussed.
相似文献2. Two techniques, subarachnoid perfusion from the supracallosal space between the hemispheres to the cisterna magna and barbotage from the cisterna magna, have been used. If the artificial c.s.f. contains Evans Blue, the former procedure results in maximum staining of the pia and underlying nervous tissue of the pons-medulla and spinal cord. The latter procedure results in maximum staining of the medial and supero-lateral surfaces of the cerebral hemispheres, particularly anteriorly.
3. During subarachnoid perfusion at 0·06 ml./min with the potassium-free fluid, most regions of the brain took up significantly greater amounts of 42K than was the case during perfusion with the fluids containing 3 and 10 m-equiv/l. For blue cerebral cortex, the tissue subjected directly to the inflowing fluid and showing the biggest differences, the ratios, c.p.m. per g brain/c.p.m. per ml. plasma, were 1·71 ± 0·12 (+44%), 1·19 ± 0·05 and 1·07 ± 0·08 (-10%) during perfusion with the fluids containing, 0, 3 and 10 m-equiv/l. respectively.
4. During barbotage, the uptake of 42K into pons-medulla and spinal cord from blood plasma, the concentration in the latter being effectively kept near constant, was, at the end of 2 hr, greater when the fluid contained potassium, 0 m=-equiv/l. rather than 10 m-equiv/l. Thus the ratio, c.p.m per g brain/c.p.m. per ml. plasma was (0·99 ± 0·04 (+36%) as against 0·73 ± 0·05 for pons-medulla where the difference was greatest.
5. Simultaneous measurements of the entry of [14C]urea from blood to different regions of the central nervous system revealed no significant differences due to the differing concentrations of potassium imposed by either barbotage or subarachnoid perfusion. This appears to exclude a non-specific cause for the changes in 42K uptake, an example of which might be a changing blood flow.
6. Reasons are given for supposing that the big increase in 42K uptake due to the potassium-free fluid must be due to events occurring at the blood—brain barrier. This might be some form of interaction, possibly the single file effect, such that a low potassium concentration in the interstitial fluid potentiates 42K influx across the blood—brain barrier. Alternatively it might be due to a low potassium concentration in this fluid greatly reducing active potassium movement from interstitial fluid to blood. The former explanation would conform neatly with the present results; but the latter would additionally be compatible with other evidence concerning the homoeostasis of potassium concentration in c.s.f. and the interstitial fluid of brain.
相似文献2. Arterial blood pH was altered over the range 7·12-7·70 by infusion of acid and alkali. When end-tidal CO2 was held constant, there was no change in intestinal blood flow.
3. When arterial blood pH was altered over the range 7·19-7·55 by the administration of CO2 at constant respiratory volume and rate, flow increased with increasing CO2.
4. The intestinal vascular bed was less responsive to noradrenaline at pH 7·2 than at pH 7·6. The change in sensitivity was evident when end-tidal CO2 was controlled and depended therefore on a change in hydrogenion concentration.
5. The dilator effect of CO2 did not depend upon alteration of sensitivity to noradrenaline since it was seen after adrenergic blockade.
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The amounts of HB ag excreted in urine, found in two chronic hepatitis patients and one HB ag carrier, were 13·2 mg, 46 mg and 82 mg/1000 ml of urine respectively.
相似文献2. During eating Pa, CO2 and Pv, CO2 both increased, pH decreased and free plasma [HCO3-] increased. Venous haematocrit increased sharply at the beginning of the meal, and declined slowly after feed was removed.
3. Arterial PO2 did not change significantly during eating. However Pv, O2 fell slightly but significantly. The O2 saturation of venous blood fell due to the decline in pH. Estimated CO2 in arterial blood increased as a consequence of increased haemoglobin content. The net effect was to increase arteriovenous difference in O2 content from 4·4 ml./100 ml. before eating to 6·0 ml./100 ml. at the end of the meal.
4. O2 consumption increased about 60% during eating and fell rapidly thereafter. Heart rate followed a similar pattern. Cardiac output however increased only about 17%, from 6 to 7 l./min. Consequently stroke volume declined throughout the meal from 76 to 52 ml./beat.
5. Plasma volume, estimated from measurements of T-1824, declined sharply by about 300 ml. at the beginning of the meal and recovered slowly after feed was removed. Blood volume declined less because of a rise in circulating erythrocytes.
6. Extracellular fluid volume was estimated from measurements of thiocyanate and thiosulphate spaces. Thiocyanate space measurements were abandoned after thiocyanate was found to be concentrated in saliva. Considerable random variation occurred in measurements of changes in extracellular fluid from thiosulphate disappearance but the results did reveal a significant fall of 1000-1500 ml. in extracellular fluid volume during eating.
7. The significance of these interrelated changes is discussed in relation to the maintenance of homoeostasis during eating in the sheep.
相似文献2. At infusion rates between threshold and 0·04 μg.kg-1.min-1 the systemic arterial pressure rose progressively over a 3- to 7-day period to a plateau.
3. On stopping the angiotensin infusion the blood pressure fell rapidly back to its base line much faster than it rose during the infusion. The time taken to reach control values was approximately related to the duration of the infusion.
4. At infusion rates of about 0·05 μg.kg-1.min-1 the full rise of blood pressure developed within a few minutes, and could be sustained without change for many days. At higher rates the blood pressure diminished with time.
5. Diurnal fluctuations of blood pressure were often seen during prolonged infusions of angiotensin at low rates; and more rapid fluctuations of blood pressure over an hour or two were frequently encountered immediately after an infusion was turned off.
6. The possible role of angiotensin in producing chronic renal hypertension is discussed in the light of these observations.
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After injection of BEP in FCA the lymph node rapidly enlarged. Within 48 hr there was depletion of lymphocytes, the enlarging lymphoid follicles had become confluent and there was proliferation of large `epithelioid' cells throughout the node. At 5 days the lymph node architecture was disorganized and lymph follicles with germinal centres could not be recognized; similar but less pronounced changes were present in regional nodes. By contrast, after injection of flagellin in FCA, there were numerous lymphocytes, plasmablasts and pyroninophilic cells, germinal centres were prominent, and the architecture was preserved.
From 0·5 to 0·8% of the total injected radioactivity was concentrated in the popliteal lymph node 2–5 days after injection of 125I BEP in FCA. No radioactivity was concentrated in the node after injection of 125I BEP without FCA, and animals thus immunized did not develop encephalomyelitis.
The popliteal lymph node was examined by autoradiography after injection of 125I BEP in FCA. At 24 hr radioactive encephalitogen associated with droplets of adjuvant was present mainly in the peripheral sinus and at 48 hr encephalitogen–adjuvant droplets were deposited randomly throughout cortex and medulla. These droplets appeared to represent sites where lymphoid cells acquired their capacity for pathogenic reactivity with their target antigen in the central nervous system.
相似文献2. Relative grain density in nucleus and cytoplasm, measured photometrically, was used as an indication of 22Na distribution within the oocyte. In test experiments grain density fell to 50% within 19 μm of the edge of the section. Owing to the large diameter of the oocyte (> 600 μm) and its nucleus (> 200 μm), this resolution was adequate to determine cytoplasmic/nuclear (C/N) ratios of grain density.
3. In oocytes fully loaded with 22Na, the mean C/N ratio was 0·92 ± 0·03 (n = 11). After 5 hr exchange in Li-substituted Na-free Ringer solution, the mean C/N ratio was 2·18 ± 0·04 (n = 11). After 5 hr exchange in Ringer solution as a control, the mean C/N ratio was 1·39 ± 0·18 (n = 7). The cytoplasm thus contained a fraction of 22Na inexchangeable with Li, and more slowly exchangeable with Na than that in the nucleus.
4. The non-Li-exchangeable fraction of internal Na thus revealed appeared to be quantitatively similar to that already demonstrated by studies of 22Na fluxes and of internal Na activity by means of Na-sensitive micro-electrodes.
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