bluuebunny/crossref_metadata_2025_split huggingface dataset:
Specific binding of atrial natriuretic peptide to rat mesenteric artery: Effect of calcium and 5-guanylylimidodiphosphate
Authors: Lyall Fiona , Morton J. J. 
Published: August 2015

1. High-dissociation equilibrium constant (20 pmol/l, receptor number 17 fmol/mg) and low-dissociation equilibrium constant (10 nmol/l, receptor number 5 nmol/mg) affinity binding sites for atrial natriuretic peptide have been identified in membrane preparations from rat mesenteric artery.
2. Tracer degradation was corrected for mathematically and binding data were analysed by a non-linear computer technique.
3. Non-atrial natriuretic peptide vasoactive hormones, angiotensin II, vasopressin and bradykinin, did not compete for the high-affinity site. Related peptides with either C- or N-terminal amino acids missing still competed, while peptides without an intact disulphide bridge did not compete.
4. Neither the addition nor the removal of calcium affected the affinity or density of binding sites. Also the non-hydrolysable guanosine triphosphate analogue 5-guanylylimidodiphosphate had no effect on either affinity or number of sites.
5. These results indicate the presence of a specific high-affinity vascular receptor for atrial natriuretic peptide which could interact with the hormone under physiological conditions. The mechanism of binding is uncertain but is unlikely to involve calcium- or guanosine triphosphate-associated regulatory sites.
Endogenous vasopressin affects postural control of blood pressure in man
Authors: Simpson H. C. R. , Zubillaga J. E. , Collier J. G. , Bennett E. D. , Mehta N. , Ang V. T. Y. , Jenkins J. S. 
Published: August 2015

1. Six healthy volunteers received intravenous infusions of isotonic (0.9% NaCl) and hypertonic (3% NaCl) saline on separate days. There were no significant changes in blood pressure or forearm blood flow, despite an increase in plasma arginine vasopressin (AVP) during hypertonic saline.
2. Immediately and 10 min after passive tilting to 50°, mean forearm blood flow fell by 17.1 and 14.3% compared with the values in the supine position during isotonic saline and by 40.3 and 43.3% during hypertonic saline. Forearm vascular resistance rose by 23.6 and 17.8% with isotonic saline and by 80.2 and 88.2% with hypertonic saline for the two readings in the tilted compared with the supine position.
3. Tilting was associated with a 14.9 and 12.1% rise in diastolic blood pressure immediately and 10 min after assuming this position during hypertonic saline, and a rise of 6.4% in mean arterial pressure.
4. The results from this study are similar to those obtained previously, when small amounts of AVP were infused. They provide further evidence that AVP may have a physiological role in the postural regulation of blood pressure.
Is low-level respiratory resistive loading during exercise perceived as breathlessness?
Authors: Lane R. , Adams L. , Guz A. 
Published: August 2015

1. The effect of adding low-level (2.7 cmH2O 1−1 s) external respiratory resistive loads on exercise-induced breathlessness has been examined in naive normal subjects; the intensity of this loading was chosen to simulate that confronting an asthmatic subject during exercise.
2. Each of 18 subjects performed two separate tests in which workload was oscillated while the respiratory loading was changed every minute between no loading, inspiratory loading only, and inspiratory plus expiratory loading. Each loading condition was given three times, and both these changes and those in workload were unpredictable as far as the subject was concerned.
3. The purpose was to ‘confuse’ subjects and obtain subjective estimates of their intensity of breathlessness independent of any expectation associated solely with the readily perceptible changes in external resistances to breathing. The study design was balanced for the group as a whole, both in terms of workload and respiratory loading condition.
4. The addition of these respiratory resistive loads during exercise did not result in a significant increase in the intensity of breathlessness.
5. Estimates of the rate of work of breathing revealed that this increased more with respiratory loading than it did as ventilation rose throughout the test; on the other hand, the intensity of breathlessness increased by a greater extent with continued exercise compared with the changes accompanying the addition of respiratory loads.
6. It is concluded that the intensity of the sensation of breathlessness experienced by normal subjects during exercise is not simply a reflection of an increased rate of work of breathing being performed by the respiratory muscles.
7. It is further suggested that similar studies in which internal resistances are increased experimentally are indicated in order to analyse the factors underlying the breathlessness of asthma.
Influence of sodium concentration in cerebrospinal fluid on plasma atrial natriuretic peptide in conscious rats
Authors: Kawano Yuhei , Yoshida Kaoru , Hirata Yukio , Yoshimi Hiroki , Kuramochi Morio , Ito Keiichi , Omae Teruo 
Published: August 2015

1. To test the influence of a sodium (Na+) stimulus within the central nervous system on the release of atrial natriuretic peptide (ANP), we examined the effects of intracerebroventricular infusion of high Na+ artificial cerebrospinal fluid (CSF) on blood pressure, urinary Na+ excretion and plasma ANP levels in conscious Wistar rats.
2. Infusion of high Na+ (0.6 mol/1) CSF into the lateral ventricle at a rate of 1 μl/min for 60 min significantly increased mean blood pressure and urinary Na+ excretion, while normal Na+ (0.15 mol/1) CSF had no effects. Plasma ANP levels were higher in the high Na+ CSF group than in the normal Na+ group (154 ±39 vs 52 ±19 pmol/l, P &lt; 0.05).
3. Interruption of the sympathetic nervous system and the vascular action of vasopressin with intravenous hexamethonium and d(CH2)5Tyr(Me)arginine vasopressin attenuated the pressor and natriuretic responses to intracerebroventricular high Na+ CSF. Plasma ANP levels in these rats did not differ significantly from those in rats which were similarly treated but were given normal Na+ CSF.
4. These results indicate that elevation of the CSF Na+ concentration without peripheral volume loading can stimulate ANP release into the circulation. ANP release due to central Na+ stimulus appears to be mediated by the sympathetic nervous system, vasopressin, and/or haemodynamic change caused by these factors.
Nucleosides and bases in synovial fluid from patients with rheumatoid arthritis and osteoarthritis
Authors: Herbert K. E. , Scott D. L. , Perrett D. 
Published: August 2015

1. Nucleosides and bases in physiological fluids result from metabolism of nucleic acids and nucleotides and from dietary sources. As nucleotide catabolism increases during tissue injury, nucleosides and bases could serve as useful biochemical markers in arthritis.
2. We have quantified nucleosides and bases in synovial fluid and plasma by high-performance liquid chromatography in order to examine whether nucleotide metabolism is increased in patients with rheumatoid arthritis and osteoarthritis.
3. At least ten u.v.-absorbing compounds were detected in plasma and synovial fluid; only urate, creatinine, hypoxanthine and uridine were present in identifiable and quantifiable amounts.
4. In synovial fluid from patients with rheumatoid arthritis the concentration of hypoxanthine was increased and that of urate decreased compared with osteoarthritis.
5. These data suggest that there is an increase in purine metabolism in the rheumatoid arthritis joint and that hypoxanthine is a potential marker of synovitis.
Acute effects of surgery on carbohydrate production and utilization in the fed rat
Authors: French Timothy J. , Holness Mark J. , Goode Anthony W. , Sugden Mary C. 
Published: August 2015

1. The work utilized a model of uncomplicated abdominal surgery (laparotomy under ether anaesthesia) to delineate the effects of abdominal trauma on glucose homoeostasis in the fed rat.
2. Regulation of glucose production and utilization was investigated by observing the response to the administration of glucose, insulin plus glucose and 5-methylpyrazole 3-carboxylic acid.
3. Glucose administration suppressed hepatic glucose output as assessed by portal–venous concentration differences in control or surgically stressed rats. In contrast, glycaemia was increased and lactaemia decreased in the latter group. Portal–venous concentrations differences for lactate were unaffected.
4. Surgery increased plasma fatty acid concentrations and the antilipolytic response to glucose or glucose plus insulin was diminished. Post-operative increases in fatty acid concentrations were associated with inhibition of hepatic pyruvate dehydrogenase complex which was reversed by insulin, indicating a differential sensitivity of adipose tissue and liver to the hormone.
5. The model of surgical stress utilized, while affecting extrahepatic glucose disposal, did not elicit depletion of liver glycogen or inactivation of l-pyruvate kinase.
6. It is concluded that the initial response to uncomplicated abdominal surgery involves carbohydrate conservation rather than increased glucose production, with effects to decrease extrahepatic glucose uptake and hepatic glucose oxidation.
Evaluation of angiogenesis in chronic inflammation by laser-Doppler flowmetry
Authors: Orlandi C. , Dunn C. J. , Cutshaw L. G. 
Published: August 2015

1. A non-invasive method is described for the assessment of angiogenesis in chronic inflammation using laser-Doppler flowmetry.
2. Significant increases in capillary blood flow were seen on days 5 and 7 after induction of subcutaneous granulomatous lesions, as compared with control skin.
3. Changes in blood flow were accompanied by changes in pulsatile flow pattern and by an intense angiogenic response observed by light microscopy.
4. The potential application of laser-Doppler flowmetry to quantitative and qualitative studies of evolving angiogenesis in pathological responses is discussed.
Effect of changes in dietary sodium on active electrolyte transport by erythrocytes at different stages of human pregnancy
Authors: Gallery E. D. M. , Rowe J. , Brown M. A. , Ross M. 
Published: August 2015

1. Active electrolyte transport was examined in erythrocytes from women in the second and third trimesters of pregnancy and post partum, and compared with that in ovulating women.
2. There was a significant reduction in intracellular sodium ([Na]i) and increase in intracellular potassium ([K]i) in pregnancy with a return towards normal values in the post-partum period.
3. Maximum specific ouabain binding [number of Na+,K+-adenosine triphosphatase (Na+,K+-ATPase) units] was increased by 70% in pregnancy and returned slowly towards normal values post partum.
4. Na+,K+-ATPase activity as determined by ouabain-sensitive 86Rb influx in artificial media was also increased in pregnancy by 13%. It returned towards normal post partum.
5. The increases in Na+,K+-ATPase in pregnancy were not closely related to the concomitant increases in aldosterone or cholesterol nor to reticulocytosis and were not affected by 7 days of high (&gt; 250 mmol/day) or low (&lt; 50 mmol/day) sodium intake.
Influence of hyperinsulinaemia on intracellular amino acid levels and amino acid exchange across splanchnic and leg tissues in uraemia
Authors: Alvestrand Anders , Defronzo Ralph A. , Smith Douglas , Wahren John 
Published: August 2015

1. To examine whether insulin resistance in uraemia extends to amino acid metabolism, the effect of physiological hyperinsulinaemia on plasma amino acid concentrations was studied in 17 chronically uraemic and 28 healthy subjects by using the euglycaemic insulin clamp technique.
2. In six uraemic and seven control subjects, splanchnic and leg exchange of amino acids was quantified with hepatic and femoral venous catheterization, and in five uraemic and eight control subjects intracellular free amino acid concentrations were determined in muscle tissue obtained by needle biopsy.
3. In response to hyperinsulinaemia the plasma concentrations of all amino acids except alanine decreased by 10–50% in both uraemic and control subjects. Splanchnic alanine uptake declined by 20% and leg amino acid release tended to decrease in both groups.
4. The intracellular levels of all measured amino acids except alanine fell significantly and to a similar extent in uraemic and control subjects.
5. These results indicate that insulin-mediated alterations in regional amino acid exchange and in plasma and intracellular amino acid concentrations are similar in uraemic and control subjects.
6. It is concluded that tissue insensitivity to insulin in uraemia does not extend to uptake or release of amino acids and that resistance to insulin can be selective in its effect on different metabolic functions.
Effect of inhaled methacholine on gas mixing efficiency
Authors: Langley F. , Horsfield K. , Burton G. , Seed W. A. , Parker S. , Cumming G. 
Published: August 2015

1. Pulmonary function tests, including alveolar mixing efficiency by the single-breath and multi-breath methods, and ventilation scans were performed on 16 volunteer subjects. The tests were repeated after the inhalation of a methacholine aerosol in sufficient dosage to increase airways resistance.
2. After inhalation of methacholine there was a significant fall in mean series dead space of 31 ml (P &lt; 0.05), and mean multi-breath alveolar mixing efficiency fell from 68% to 36% (P &lt; 0.001), a fall occurring in all subjects. Mean single-breath alveolar mixing efficiency measured on the first breath of the nitrogen washout fell from 76% to 70%, but this change did not reach statistical significance (0.1 &gt; P &gt; 0.05).
3. In eight of the subjects, technically adequate lung scans and pulmonary function tests were obtained both before and not more than 30 min after methacholine inhalation. In seven there were obvious visible defects on the ventilation scans, and in five of these the computer-calculated underventilation score became abnormal.
4. Thus inhalation of methacholine causes maldistribution of ventilation, a fall in alveolar mixing efficiency and a fall in series dead space, presumably brought about by bronchoconstriction. The parallel component of this maldistribution of ventilation, as judged by 81mKr ventilation scanning, does not of itself seem to be sufficient to explain the fall in alveolar mixing efficiency, and therefore a degree of diffusion limitation is probably involved as well.
Low dose infusion of atrial natriuretic peptide causes salt and water excretion in normal man
Authors: Morice Alyn , Pepke-Zaba Joanna , Loysen Elena , Lapworth Ruth , Ashby Michael , Higenbottam Tim , Brown Morris 
Published: August 2015

1. The effects of low dose infusion of atrial natriuretic peptide (ANP) were observed in a double-blind, placebo-controlled study in six fluid-loaded volunteers. After baseline observations, hourly increments of 0.4, 2 and 10 pmol min−1 kg−1 were infused with continuous observation of heart rate, blood pressure and cardiac output. Plasma ANP, aldosterone, and catecholamines, and urinary volume and sodium excretion, were estimated at half-hourly intervals.
2. ANP infusion resulted in an increase of 35, 98 and 207% in urinary sodium excretion and of 10, 20 and 71% in urinary volume when compared with placebo. Plasma ANP was markedly elevated above placebo levels only during infusion of 10 pmol of ANP min−1 kg−1.
3. No change in heart rate or blood pressure was noted during the study, but a significant fall in stroke volume index was observed during active treatment. Plasma levels of aldosterone and catecholamines were not significantly different on the 2 treatment days.
4. The potent natriuretic and diuretic effects of this peptide at plasma concentrations not significantly elevated from physiological suggest a hormonal role for ANP in the homoeostasis of salt and water balance.
Rapid changes in plasma potassium during a game of squash
Authors: Struthers A. D. , Quigley C. , Brown M. J. 
Published: August 2015

1. The game of squash has recently been associated with a high incidence of ventricular arrhythmias and sudden death. To investigate this further, plasma catecholamines and potassium (K+) were monitored during a game of squash in six normal volunteers.
2. No cardiac arrhythmias were seen in this study despite the subjects reaching maximum heart rates of 181 ± 5 beats/min (mean ± sem).
3. During exercise, plasma K+ rose from 3.82 ± 0.16 to 4.29 ± 0.2 mmol/l, but after 90 s rest this fell to 3.68 ± 0.28 mmol/l and after 180 s to 3.44 ± 0.17 mmol/l. This rapid K+ shift could not be accounted for by generalized changes in venous acid-base status or by changes in venous plasma catecholamines. Although pre-treatment with a β2-antagonist caused the overall plasma K+ levels to be higher, it had no significant effect on the fall in plasma K+ after exercise.
4. Such rapid K+ shifts after exercise might contribute to arrhythmogenesis in susceptible individuals. The precise mechanism of the fall in K+ after exercise remains undetermined, but it seems not to involve catecholamines stimulating β2-adrenoceptors and is more likely to be due to increased skeletal muscle blood flow and/or intracellular acidosis.
Effects of angiotensin II and atrial natriuretic peptide alone and in combination on urinary water and electrolyte excretion in man
Authors: McMurray J. , Struthers A. D. 
Published: August 2015

1. Atrial natriuretic peptide (ANP) has previously been shown to inhibit the renin–angiotensin–aldosterone system (RAAS) at several different levels. We have now investigated a further non-endocrine, renal interaction between ANP and the RAAS.
2. The effects of ANP and angiotensin II (ANG II) alone, and in combination, on urinary electrolyte and water excretion were studied in eight normal male subjects undergoing maximal water diuresis.
3. ANP caused a significant increase in urine flow and sodium excretion. ANG II alone was antidiuretic, antinatriuretic and antikaliuretic. When ANP was given against a background infusion of ANG II, urinary flow rate and electrolyte excretion increased from a new lower level to reach a value intermediate between that found with ANG II alone and ANP alone.
4. It is concluded that the renal effects of ANP are modified in the presence of simultaneously elevated levels of ANG II and that net water and electrolyte excretion reflect the sum of the opposing influences of each peptide. While this interplay may be non-specific, it is possible that ANP may exert some of its actions by specifically inhibiting the intrarenal effects of ANG II.
Prostaglandins E2 and F2α are not involved in the monocytic-product (interleukin-1)-induced stimulation of hepatic fibrinogen synthesis in rats
Authors: Holtslag J. C. W. M. , Moshage H. J. , van Pelt J. F. , Kleuskens J. A. G. M. , Gribnau F. W. J. , Yap S. H. 
Published: August 2015

1. Monocytic products, especially interleukin-1 (IL-1), play an important role in the acute-phase response. Prostaglandins have been shown to act as second messengers in several physiological alterations of the acute-phase response, such as fever, muscle wasting and immunoregulation. The present study was undertaken to determine the role of prostaglandins in the monocytic-product-induced stimulation of the hepatic synthesis of fibrinogen, a well-known acute-phase protein.
2. Prostaglandin (PG) E2, PGF2α and 16,16-dimethyl-PGE2 did not stimulate fibrinogen synthesis and fibrinogen polypeptide mRNA content when administered intraperitoneally to rats or when added to monolayer cultures of rat hepatocytes.
3. Cyclo-oxygenase inhibitors did not abolish the stimulation of fibrinogen synthesis and its mRNA content induced by monocytic products in vivo or in vitro.
4. These findings indicate that the enhanced synthesis of fibrinogen induced by monocytic products (including IL-1) during the acute-phase response is not mediated by prostaglandins or other products of the cyclo-oxygenase pathway of arachidonic acid.
Partial enterectomy decreases somatostatin-binding sites in residual intestine of rabbits
Authors: Colas B. , Bodegas G. , Sanz M. , Prieto J. C. , Arilla E. 
Published: August 2015

1. Three weeks after partial enterectomy in the rabbit there was an increased somatostatin concentration and a decreased number of somatostatin-binding sites (without changes in the corresponding affinity values) in the cytosol of the residual intestinal tissue, except in the terminal ileum and the colon.
2. Five weeks after surgery both the somatostatin concentration and the number of somatostatin-binding sites returned towards control values.
3. These results suggest that an increase in bowel somatostatin content could lead to down-regulation of somatostatin-binding sites in the intestinal mucosa.
A renorenal suppression in response to atrial natriuretic peptide in the unilateral ischaemic rat
Authors: Torikai Shozo 
Published: August 2015

1. The present study was carried out to investigate the haemodynamic and natriuretic effects of atrial natriuretic peptide (ANP) in normal rats and in rats with unilateral ischaemia.
2. Twenty-four hour unilateral ureter occlusion gave rise to a marked vasoconstriction in the ipsilateral kidney after its release. Intravenous infusion of ANP doubled p-aminohippurate clearance and inulin clearance and elicited massive natriuresis in the hydronephrotic kidney, while in the contralateral kidney these clearance values were decreased and there was a lack of natriuresis. The responses in the latter kidney were also different from those in the normal rat, in which significant natriuresis was elicited by ANP even though a decrease in p-aminohippurate clearance occurred.
3. After the control kidney in the unilateral hydronephrotic rat was denervated either mechanically or by pretreatment with prazosin, ANP induced a natriuresis in both kidneys. Furthermore, the renal denervation prevented the decrease in inulin clearance in the control kidney after ANP administration.
4. These findings suggest that the renal response to ANP may depend on the vascular tone before administration, and that renal nerve activity may modify the effects of ANP on renal haemodynamics and sodium excretion.
2,3-Diphosphoglycerate in normal, anaemic and transfused human fetuses
Authors: Soothill P. W. , Lestas A. N. , Nicolaides K. H. , Rodeck C. H. , Bellingham A. J. 
Published: August 2015

1. The effect of anaemia and transfusion with adult blood on fetal 2,3-diphosphoglycerate levels was investigated by studying fetal blood from 45 normal pregnancies at 17–42 weeks of gestation and in 34 pregnancies complicated by erythroblastosis fetalis.
2. In normal fetuses, 2,3-diphosphoglycerate concentration was higher than in adults and did not change significantly with gestational age.
3. In erythroblastotic fetuses, there was a significant negative correlation between 2,3-diphosphoglycerate concentration and haemoglobin concentration.
4. When adult blood was transfused into the fetal circulation, 2,3-diphosphoglycerate concentration reached similar levels to that found in untransfused fetuses after allowing for the severity of anaemia.