bluuebunny/crossref_metadata_2025_split huggingface dataset:
Angiotensin II Binding to Human Mononuclear Cells: Receptor or Free Fluid Endocytosis?
Authors: Neyses L. , Locher R. , Wehling M. , Pech H. , Tenschert W. , Vetter W. 
Published: August 2015

1. It has recently been claimed that there are angiotensin II (ANG II) receptors on human mononuclear cells and on platelets and this has been used for investigating the regulation of the renin-angiotensin system in hypertension. We here show the following.
2. Binding kinetics of 125I-labelled ANG II and [3H]ANG II to mononuclear cells were slow (maximum at 90 min) and the same as for [3H]-inulin.
3. As with [3H]inulin there was no binding at 4°C.
4. Release from the cells was slow and incomplete (about 30% after 15 min, 60% after 60 min).
5. Binding was not saturable over a range from 10−12 to 10−6 mol of ANG II/l, about 8% of offered peptide being bound at all concentrations.
6. Various inhibitors of free fluid endocytosis exhibited the same inhibition pattern of ANG II binding to mononuclear cells.
7. Therefore uptake of ANG II into mononuclear cells displayed all the features of free fluid endocytosis.
8. ANG II was degraded by carboxypeptidase A. When this degradation was prevented by d-phenylalanine, no binding occurred.
9. In platelet preparations contaminated by 0.3-5% of mononuclear cells, 125I-labelled ANG II was degraded as well. Free fluid endocytosis of the degradation product strongly depended on the percentage of contaminating mononuclear cells.
10. We conclude that there are no ANG II receptors on human mononuclear cells and that their presence on human platelets is doubtful.
Intracerebroventricular Infusion of Sodium Chloride-Rich Artificial Cerebrospinal Fluid in Rats Induces Natriuresis and Releases An Inhibitor of Prostaglandin Synthesis
Authors: Diez Javier , Colina Inmaculada , Guarner Francisco , Quiroga Jorge , Corzo Julio , Purroy Andrés , Prieto Jesús 
Published: August 2015

1. Urinary sodium excretion in anaesthetized rats subjected to high-sodium artificial cerebrospinal fluid (CSF) infusion into the lateral brain ventricle, was significantly higher than in rats infused with normal-sodium CSF.
2. Urinary immunoreactive 6-ketoprostaglandin F1α, the stable derivative of prostacyclin, was significantly reduced in the high-sodium CSF group, as compared with the normal-sodium CSF group.
3. When dog aortic endothelium was incubated in the presence of plasma, endothelial prostacyclin production was found to be inhibited by plasma from rats infused with high-sodium CSF compared with the effect of plasma from the rats infused with normal-sodium CSF.
4. Our results indicate that intracerebroventricular infusion of high-sodium CSF induces a natriuretic response and is associated with the appearance of a humoral factor which blocks prostacyclin byosynthesis.
The influence of environmental temperature upon the thermoregulatory responses to ethanol in man
Authors: Fellows I. W. , MacDonald I. A. , Bennett T. 
Published: August 2015

1. Ten healthy male subjects ingested ethanol (BP; 0.5 g/kg body weight) after an overnight fast, on two separate occasions, at environmental temperatures of either 21°C or 3O°C.
2. The mean maximal fall in deep body temperature was not significantly different on the two occasions, being 0.18°C and 0.17°C respectively.
3. Metabolic rates throughout the experiments at the two temperatures were not significantly different.
4. The vasodilatation of the hand and forearm vascular beds after ethanol ingestion was markedly reduced at the lower environmental temperature.
5. In three subjects who ingested a higher dose of ethanol (BP; 1.0 g/kg body weight) after an overnight fast, at an environmental temperature of 2l°C, the mean maximum fall in core temperature was 0.15°C, which was not significantly different from the change seen after consumption of the lower dose of ethanol.
6. It is likely that the failure of ethanol ingestion to provoke hypothermia at the lower environmental temperature was due to the attenuated vasodilatation observed under these conditions.
β-Adrenoceptors and Responsiveness in Cardiac Hypertrophy Associated with Renal Hypertension in Renovascular Hypertensive Rats
Authors: Ayobe M. Hani , Tarazi Robert C. 
Published: August 2015

1. The possible contribution of changes in cardiac β-adrenoceptors to alterations in cardiac responses to isoprenaline were investigated in hearts isolated from rats with renovascular hypertension (two-kidney, one-clip Goldblatt), 6, 12 and 18 weeks after renal artery clipping. Cardiac responses were determined in vitro (Langendorff preparation), and ventricular β-adrenoceptors ([3H)dihydroalprenolol, [3H]DHA) were then assayed in the same 44 hearts.
2. There was no difference between renovascular hypertensive rats (RHR) and matched normotensive controls as regards chronotropic responses to isoprenaline or in atrial β-adrenoceptor numbers or apparent affinity.
3. Inotropic responses were significantly lower in all stages of RHR than in matched normotensive controls.
4. There was also a significant (P &lt; 0.001) decrease in ventricular β-adrenoceptor density with no significant change in apparent affinity (Kd). Inotropic responsiveness to isoprenaline (max. increment in peak dP/dt) was significantly correlated with ventricular β-adrenoceptor density (r = 0.54, P = 0.0005).
5. These results suggest that the reduction of ventricular β-adrenoceptor density in that model of hypertension was responsible, at least partially, for the lowered inotropic responsiveness of the same hearts to isoprenaline.
Post-Exercise Reduction of Blood Pressure in Hypertensive Men is Not Due to Acute Impairment of Baroreflex Function
Authors: Bennett T. , Wilcox R. G. , MacDonald I. A. 
Published: August 2015

1. Two experiments were carried out in male subjects. In the first experiment heart rate and blood pressures were measured before, during and for 90 min after a 50 min period of intermittent exercise in seven hypertensive subjects. After exercise there was a marked reduction in systolic and diastolic blood pressures; this effect lasted throughout the 90 min observation period and was unaccompanied by tachycardia.
2. In the second experiment heart rate and blood pressures were measured before and during the rest periods in a 50 min session of intermittent exercise in nine hypertensive and nine normotensive subjects. Following the first 10 min bout of exercise, resting blood pressures were significantly reduced in the hypertensive subjects; the reduction in blood pressure progressively increased following successive exercise periods. The normotensive subjects did not show a significant reduction in resting blood pressures until the fifth bout of exercise had been completed.
3. In the second experiment also, the competence of baroreflexes was assessed by measuring cardiovascular responses to lower body sub-atmospheric pressure (LBSP) 30 min before and 30 and 60 min after exercise. The post-exercise reduction in blood pressure was not due to exercise-induced impairment of baroreflex mechanisms since the reduced blood pressure after exercise was well maintained during lower body sub-atmospheric pressure. Furthermore, after exercise, exposure to lower body subatmospheric pressure elicited greater increases in heart rate and forearm vascular resistance than were seen before exercise.
A Micropuncture and Renal Clearance Study in the Rat of the Urinary Excretion of Heparin, Chondroitin Sulphate and Metabolic Breakdown Products of Connective Tissue Proteoglycans
Authors: Shum Daisy K. Y. , Baylis Christine , Scott John E. 
Published: August 2015

1. Commercial heparin and acid glycosaminoglycans (AGAG) prepared from normal female human urine were tritiated catalytically in aqueous solution. Nasal septal chondroitin sulphate was tritiated by NaB3H4 reduction of the aldehydes produced by very limited periodate oxidation. The refined products were characterized by electrophoresis and biochemical analysis.
2. The tritiated products were infused into Munich-Wistar rats, and their kidney clearances were measured and compared with that of inulin.
3. The passage of heparin and chondroitin sulphate at the glomerulus was restricted, as shown by the ratios of their concentrations in Bowman's space fluid and plasma. Comparison with whole kidney urine/plasma ratios indicated that some tubular reabsorption also occurred. The low whole kidney clearance of AGAG from normal female human urine probably also resulted from restricted glomerular passage and tubular reabsorption.
4. The low whole kidney clearances, primarily caused by restricted transglomerular movement, are discussed on the bases of (a) the molecular sizes and shapes of the AGAG, (b) an electrostatic barrier at the basement membrane and (c) binding of AGAG to plasma colloids, thus reducing plasma levels of free AGAG.
5. The implications of these findings in (a) heparin therapy and (b) urinalysis of disorders of connective tissue metabolism are discussed.
The effects of Acute and Chronic β-Adrenoceptor Blockade on the Myofibrillar Contractile System in the Dog Heart
Authors: Davies M. K. , Cummins P. , Littler W. A. 
Published: August 2015

1. Electrophoretic and enzyme techniques have been used to study the structure and function of the contractile protein system in the myocardium of dogs before and after β-adrenoceptor blockade. Animals were examined after acute β-adrenoceptor blockade by using intravenous atenolol (0.2 mg/kg) and following chronic therapy with oral atenolol (100 mg twice daily) for a mean period of 106 days.
2. Two-dimensional polyacrylamide-gel electrophoretic techniques were used to examine the myocardial contractile and regulatory proteins present in endomyocardial biopsy specimens obtained after acute and chronic β-adrenoceptor blockade. No differences in charge, molecular weight or the relative proportions of actin, myosin light chains, tropomyosin or troponin-C were seen after either acute or chronic β-adrenoceptor blockade.
3. The maximal activity and calcium sensitivity of the myofibrillar adenosine triphosphatase (ATPase) was also unchanged after acute and chronic atenolol therapy.
4. It is concluded that β-adrenoceptor blockade has no significant adaptive effect on the structural or functional properties of the myofibril.
Sex-Related Differences in Resting and Stimulated Plasma Noradrenaline and Adrenaline
Authors: Davidson L. , Vandongen R. , Rouse I. L. , Beilin L. J. , Tunney A. 
Published: August 2015

1. Resting and stimulated plasma noradrenaline and adrenaline concentration were compared in 45 females and 45 males of similar age who did not smoke, drink alcohol or caffeine-containing beverages.
2. At rest plasma noradrenaline levels were consistently higher in females and adrenaline levels higher in males. These sex-related differences were maintained after isometric exercise, mental arithmetic and cold pressor testing.
3. Resting noradrenaline concentration was negatively correlated with Quetelet index in males and positively correlated with age in females.
4. These findings, based on precise catecholamine measurements under standardized conditions in subjects of similar age, reveal important sex-related differences which need to be taken into account in assessing sympatho-adrenal activity, particularly in relation to mechanisms in essential hypertension.
The Effects of a Chronic Infusion of Arginine Vasopressin in Salt-Restricted, Water-Deprived Man
Authors: Drew P. J. T. , Barnes J. N. , Holly J. M. P. , Knight A. , Goodwin F. J. 
Published: August 2015

1. The effects of a 48 h infusion of arginine vasopressin (AVP) were measured in five separate studies on four normal salt-restricted physicians, in whom fluid retention was prevented.
2. The infusion was associated with an increase in renal sodium excretion which continued during the 24 h after the infusion had been discontinuted.
3. During the infusion plasma renin activity (PRA), plasma aldosterone and noradrenaline, and packed cell volume (PCV) fell; glomerular filtration rate, assessed by endogenous creatinine clearance, increased.
4. The findings are best explained by a vasopressin-induced increase in plasma volume, which in the absence of fluid retention is likely to have been due to a redistribution of body water.
Uptake and Metabolism of Thyroid Hormones by the Rat Foetus in Early Pregnancy
Authors: Woods R. J. , Sinha A. K. , Ekins R. P. 
Published: August 2015

1. Pregnant rats were injected with trace amounts of [125I] thyroxine ([125I]T4) or [125I]-tri-iodothyronine ([125I]T3).
2. Maternal blood, organs and foetuses were removed 1 and 4 h later, homogenized and trichloroacetic acid added to precipitate radio-labelled iodothyronines.
3. An hour after injecting [125I]thyroxine, 9–10 day old foetuses contained 21% of the radiolabel found in the same weight of plasma whereas by 13–14 days they contained 0.6%.
4. An hour after injection of [125I]tri-iodothyroninetri-iodothyronine, 9–10 day old foetuses contained 54% of the radioactivity present in the same weight of plasma.
5. When related to tissue protein, the radio-labelled iodothyronine content in 9–10 day old foetuses was comparable with that in maternal brain, heart or ovary.
6. De-iodination of [125I]thyroxine in 9–10 day old foetoplacental units was equal to that in maternal liver but greater than that in brain or heart.
7. It is concluded that substantial amounts of thyroxine and tri-iodothyronine enter the rat foetus in early pregnancy but thyroxine uptake may be minimal in later pregnancy.
Atrial Natriuretic Factor: Sodium Transport in Human Erythrocytes
Authors: Trippodo Nick C. , Cole Francis E. , MacPhee Allan A. 
Published: August 2015

1. The effect of partially purified rat atrial natriuretic factor on sodium efflux from sodium-loaded human erythrocytes was studied.
2. High molecular weight (10000–30000) and low molecular weight (3000–10000) fractions of atrial extract were prepared by gel filtration; they had natriuretic activity in rats.
3. Neither fraction affected sodium efflux in erythrocytes.
4. The results suggest that atrial natriuretic factor acts in the kidney by mechanisms other than through inhibition of the Na+-K+ exchange pump or the Na+-K+ cotransport system.
Ouabain-Resistant, Frusemide-Sensitive Sodium Efflux in Human Lymphocytes: A Comparison of Normotensive and Hypertensive Subjects
Authors: Montanari A. , Simoni Isabella , Sani E. , Schianchi P. , Borghetti A. , Novarini A. 
Published: August 2015

1. Peripheral blood lymphocytes were isolated at room temperature in a low sodium medium in 17 normotensive control subjects (NC) and 13 patients with essential hypertension (EHP).
2. Lymphocyte sodium content was not significantly different between NC and EHP (3.1 ± 0.5, n = 11, and 3.6 ± 0.5, n = 10, respectively; means ± sem).
3. The effect of frusemide on the ouabain-resistant rate constant of sodium efflux (KNao) from these lymphocytes into a sodium-free medium was measured.
4. The frusemide-sensitive efflux rate constant was 75 ± 5 μs (n = 17) in controls and significantly lower in EHP (32 ± 7 μs, n = 13, P&lt;0.001).
5. In human lymphocytes there is a ouabain-resistant, frusemide-sensitive fraction of sodium efflux into a sodium-free medium; this fraction may be reasonably attributed to a sodium-potassium cotransport system. This sodium transport pathway seems to be reduced in lymphocytes from EHP.
Arterial Plasma Potassium Measured Continuously during Exercise in Man
Authors: Linton R. A. F. , Lim M. , Wolff C. B. , Wilmshurst P. , Band D. M. 
Published: August 2015

1. Five continuous records of arterial plasma potassium were obtained from three normal subjects during brief periods (5–7 min) of exercise (100 W).
2. In two of these subjects hepatic venous blood samples were withdrawn at 0.5–1.0 min intervals and analysed in vitro for plasma potassium.
3. Arterial plasma potassium rose rapidly at the start of exercise from 3.8 ± 0.3 mmol/l (mean ± sd) to plateau levels of 5.4 ± 0.1 mmol/l.
4. One of the above subjects and a further subject were studied after β-blockade with propranolol. This resulted in an exaggerated rise in arterial plasma potassium during exercise.
5. Hepatic venous potassium measurements indicated that the liver probably had little effect on potassium changes during exercise.
6. The changes in arterial plasma potassium during exercise are rapid and substantial. If transmitted to the extracellular fluid these changes would alter cell transmembrane potential and might as a result alter receptor sensitivity.
The Effect of a 48h Fast on the Thermoregulatory Responses to Graded Cooling in Man
Authors: MacDonald I. A. , Bennett T. , Sainsbury R. 
Published: August 2015

1. The thermoregulatory responses to graded cooling were measured in 11 healthy male subjects after a 12 h fast and after a 48 h fast. The cooling stimulus was produced by changing the temperature of the skin of the trunk and legs with a water-perfused suit. Five levels of skin temperature from 35.5 to 24°C were applied on each occasion.
2. After a 12 h fast, core temperature was maintained during cooling. This maintenance of core temperature was associated with an increase in metabolic rate and a reduction in blood flow to the hand and to the forearm.
3. After 48 h of fasting, the subjects could not maintain core temperature during cooling, and a decrease of 0.36 ± 0.05°C occurred as the suit temperature was reduced from 35.9 to 24°C. Metabolic rate was slightly higher after the 48 h fast than after the 12 h fast, but similar increases in metabolic rate were observed during cooling.
4. Vasoconstriction in the hand was initially less after a 48 h fast than after a 12 h fast, but at the lowest suit temperature, hand blood flow was similar, and low, on both occasions. After 48 h of fasting, forearm blood flow was elevated at all suit temperatures, being approximately twice the level recorded after the 12 h fast.
5. Venous plasma noradrenaline levels did not change during cooling after the 12 h fast, whilst after 48 h of fasting a significant increase in noradrenaline level was observed at the lowest suit temperature.
6. The results of this study provide further evidence that fasting induces an impairment of autonomic reflex mechanisms, but it is not clear whether this is due to a suppression of sympathetic nervous activity.
Effect of Hyperthyroidism on Hepatic Lipogenesis in Rats: Studies in Vivo and in Vitro
Authors: Al-Saadi Amal S. , Orr J. Stewart , Goode Anthony W. , Sugden Mary C. 
Published: August 2015

1. Lipogenic rates (measured with 3H2O) in hepatocytes from fed or starved euthyroid rats were similar in magnitude to those measured in livers in vivo. Hepatic lipogenesis in vivo in fed triiodothyronine (T3)-treated rats was greater than in fed control rats, but rates in vitro were only 16% of those of control rats. It is concluded that hepatic lipogenesis in vivo in T3-treated rats utilizes precursors from extrahepatic tissues.
2. Glycogen depletion of hepatocytes from fed control rats decreased lipogenesis, and rates were then similar to those in hepatocytes from fed T3-treated rats. Addition of lactate (2 mmol/l) and pyruvate (0.2 mmol/l) had little stimulatory effect on lipogenesis in hepatocytes from fed control rats, but increased lipogenesis in glycogen-depleted hepatocytes (by 86%), hepatocytes from starved rats (by 25%) and hepatocytes from T3-treated rats (by 60%).
3. In the presence of lactate and pyruvate, 3-mercaptopicolinate (3-MPA) (an inhibitor of gluconeogenesis) did not affect lipogenesis in hepatocytes from fed control rats but substantially increased lipogenesis in hepatocytes from starved euthyroid rats or fed hyperthyroid rats. Thus, in hepatocytes from starved euthyroid rats or fed hyperthyroid rats gluconeogenesis competes with lipogenesis for available precursors (lactate and pyruvate). In contrast, in fed rats carbon flux is predominantly towards lipogenesis.
4. Effects of 3-MPA in the presence of lactate and pyruvate were much less in glycogen-depleted cells from fed rats than in hepatocytes from starved or T3-treated rats. Thus glycogen depletion per se does not cause a redirection of carbon flux.
Intracellular pH and Electrolytes in Human Skeletal Muscle during Adrenaline and Insulin Infusions
Authors: Sahlin K. , Henriksson J. , Juhlin-Dannfelt A. 
Published: August 2015

1. There is evidence that both β-adrenergic stimulation and insulin are of importance in controlling intracellular pH. Therefore we have investigated the influence of intravenous infusion of adrenaline or insulin glucose (euglycaemic clamp) on pH and electrolyte composition in resting skeletal muscle (m. quadriceps femoris) and arterial blood in six healthy subjects.
2. A decrease in the arterial potassium concentration was observed during infusion of adrenaline and is in conformity with previous studies. Both adrenaline and insulin infusions resulted in an increased lactate content of muscle and blood, indicating an enhanced glycolysis. The intracellular concentrations of K+, Na+, Mg2+ and H+, however, remained unchanged during the adrenaline infusions as well as during infusions of insulin.
3. It is concluded that increasing the plasma adrenaline and insulin concentrations to levels well above the physiological range (adrenaline) or in the upper physiological range (insulin) does not affect the concentrations of electrolytes and hydrogen ions in resting human muscle to any appreciable extent.
Relationship between Ventilation and Breathlessness during Exercise in Chronic Obstructive Airways Disease is not Altered by Prevention of Hypoxaemia
Authors: Swinburn C. R. , Wakefield J. M. , Jones P. W. 
Published: August 2015

1. We have examined the hypothesis that hypoxaemia contributes to breathlessness by a mechanism distinct from its action as a ventilatory stimulant.
2. Five patients who developed arterial oxygen desaturation during incremental exercise were studied. Exercise tests were performed on a cycle-ergometer. Breathlessness was measured by using a visual analogue scale technique. All five patients had considerable previous experience of these procedures.
3. Two identical exercise tests were performed by each patient, breathing either room air or 60% oxygen in a blind randomized study.
4. Breathing air, arterial saturation at rest was 93% and fell by 7% during exercise. Breathing 60% oxygen, resting saturation was 98% and there was no fall during exercise.
5. Breathing oxygen, ventilation for a given work load was reduced and exercise duration was increased when compared with air breathing.
6. In each of the five patients the relationship between breathlessness and minute ventilation was the same whether breathing air or 60% oxygen, despite the reduction in ventilation for a given work rate.
Hypertension Produced by Chemical Renal Medullectomy: Evidence for a Renomedullary Vasodepressor Function in the Rat
Authors: Taverner D. , Bing R. F. , Fletcher A. , Russell G. , Swales J. D. , Thurston H. 
Published: August 2015

1. The rat renal papilla was selectively destroyed by 2-bromoethylamine hydrobromide; increasing doses produced a graded severity of histological damage, polyuria and a reduction in urinary prostaglandin E2 excretion.
2. Destruction of at least half of the papilla caused significant hypertension, but plasma renin concentration and plasma creatinine did not change.
3. After graded medullary damage Goldblatt two-kidney, one-clip hypertension was induced. Four weeks later the severity of hypertension was similar in medulla-damaged and medulla-intact groups.
4. When Goldblatt two-kidney, one-clip hypertension was reversed by removal of the renal artery clip, the blood pressure fall was less when the inner renal papilla was ablated than when it was intact, although plasma renin concentration and sodium balance were similar. The final blood pressure was similar to that observed in normal rats treated with 2-bromoethylamine compared with their respective controls.
5. These findings are consistent with the hypothesis that the inner renal medulla produces a vasodepressor that influences blood pressure in normal rats, and also lowers blood pressure when two-kidney, one-clip hypertension is reversed surgically.