bluuebunny/crossref_metadata_2025_split huggingface dataset:
β-Adrenoceptor responsiveness and plasma catecholamines as determinants of cardiovascular reactivity to mental stress
Authors: Eisenhofer G. , Lambie D. G. , Johnson R. H. 
Published: August 2015

1. Twenty-five normotensive men were subjected to two periods of mental stress involving a cognitive task and a competitive electronic game. Plasma catecholamines, heart rate and blood pressure were measured before and during mental stress. Responsiveness to β-adrenoceptor stimulation was also determined in each subject by measurement of heart rate responses to bolus injections of isoprenaline.
2. Both periods of mental stress were associated with significant increases in systolic and diastolic blood pressures, heart rate and plasma adrenaline, but not plasma noradrenaline. Heart rate responses to mental stress varied widely, with increases ranging from 1 to 48 (mean ± sd 13.5 ± 10.6) beats/min for the cognitive task and from 2 to 49 (20.4 ± 14.0) beats/min for the electronic game. Systolic blood pressure responses also varied widely and showed significant positive correlations with heart rate responses.
3. Significant relationships were found between heart rate responses to both forms of mental stress and cardiac sensitivity to isoprenaline, subjects with low responsiveness to β-adrenoceptor stimulation tending to have smaller heart rate responses to mental stress than subjects with high responsiveness to β-adrenoceptor stimulation. Relationships were also found between plasma adrenaline responses and heart rate responses to mental stress, although these did not reach significance. Considerably improved relationships were found when heart rate responses were correlated with a single variable generated from the product of the adrenaline response and the inverse of the dose of isoprenaline required to raise heart rate by 25 beats/min.
4. It is concluded that wide variation is shown between different individuals in responsiveness to β-adrenoceptor stimulation and that this is an important factor in the variability between individuals in heart rate and systolic blood pressure responses to mental stress. Both catecholamines and adrenoceptor-mediated responses to catecholamines should be examined when determining the physiological basis for differences in cardiovascular reactivity to mental stress between individuals or groups.
Right ventricular hypertrophy and polycythaemia in rats after intermittent exposure to hypoxia
Authors: Moore-Gillon J. C. , Cameron I. R. 
Published: August 2015

1. Six groups of 20 male adult rats were maintained in an environmental chamber, each group for a period of 28 days. One group breathed air throughout its experimental period, and a second group breathed a normobaric atmosphere of 12% oxygen. The other four groups were exposed to this hypoxic atmosphere for only a proportion of each 24 h cycle: 2, 4 and 12 h daily, and eight periods of 30 min daily.
2. After 28 days, measurement was made, in each rat, of right ventricule (RV) weight and of red cell mass (RCM) by using 51Cr-labelled rat erythrocytes.
3. In the normoxic control group, RV weight corrected for log body weight in grams was 63.2 ± 1 mg/log body wt. and RCM was 2.02 ± 0.05 ml/100 g body wt. This was significantly less than in the group hypoxic for only 2 h each day for 28 days: RV weight 66.6 ± 0.8 mg/log body wt. (P &lt; 0.05) and RCM 2.27 ± 0.05 ml/100g body wt. (P &lt; 0.05). Greater increases compared with control were observed in all the other hypoxic groups. There was no significant difference in the increases in RV weight and RCM produced by daily hypoxia in a 4 h continuous period and daily hypoxia in eight 30 min periods.
4. The possible role of intermittent hypoxia in producing polycythaemia and pulmonary hypertension has been the subject of much speculation. Our results show that intermittent hypoxia is a potent stimulus to erythropoiesis and to pulmonary hypertension, reflected in RV hypertrophy. They support the view that abnormalities of respiration during sleep may be responsible for the polycythaemia and cor pulmonale seen in some patients with sleep apnoea syndromes and with chronic obstructive airways disease.
Kinetics of bumetanide-sensitive Na+-K+ co-transport in erythrocytes of essential hypertensive patients
Authors: Delva Pietro , De Gasperi Mario , Degan Maurizio , Covi Grazia , Lechi Alessandro 
Published: August 2015

1. Outward bumetanide-sensitive Na+-K+ co-transport was studied in the erythrocytes of 51 subjects, 24 normotensive subjects and 27 hypertensive patients, matched for sex and age.
2. Three kinetic parameters of this cation transport system were considered: velocity of efflux at saturating internal sodium (Nai) concentrations (Vmax.), apparent affinity for sodium (K50%) and index of co-operativity among Nai sites (Hill's n).
3. We correlated these values with clinical and laboratory data determined routinely in hypertension.
4. There were no significant differences between normotensive and hypertensive subjects for the values considered and we did not find any significant correlations between co-transport and clinical data.
d-Sotalol: a new potent class III anti-arrhythmic agent
Authors: Taggart Peter , Sutton Peter , Donaldson Robert 
Published: August 2015

1. We have compared the effect of a new drug d-sotalol which has minimal β-blocking action with the parent (β-blocking) compound dl-sotalol on monophasic action potential (MAP) duration in open-chested dogs. In seven experiments d-sotalol was administered in intravenous bolus doses of 1.5, 3 and 6 mg/kg given at 10 min intervals. In a further seven experiments dl-sotalol was administered using the same dosage regimen.
2. The animals were anaesthetized with chloralose and urethane. Atrioventricular block was created by injection of the bundle of His with 0.1 ml of 40% formalin in order to ensure capture by ventricular pacing. After prior β-blockade with propranolol (0.25 mg/kg), simultaneous epicardial and endocardial MAP were recorded at paced heart rates of 100 and 150 beats/min after each bolus injection. d-Sotalol and dl-sotalol showed similar prolongation of MAP duration (measured at 90% repolarization) in both endocardial and epicardial recording at both paced heart rates.
3. These results show that the dextro-isomer of sotalol possesses similar class III action to the parent compound and that this action is homogeneous with respect to left ventricular endocardium and epicardium at heart rates of 100 beats/min and 150 beats/min over a wide dose range. d-Sotalol may be a useful anti-arrhythmic agent in man.
Baroreflex sensitivity and pressor responses in a rat model of uraemia
Authors: Watson Alan J. , Di Pette Donald 
Published: August 2015

1. Baroreflex sensitivity and pressor responsiveness to exogenous noradrenaline, angiotensin II and arginine vasopressin were determined in a rat model of uraemia.
2. The slope of the regression line relating Δheart rate to Δblood pressure after phenylephrine administration was significantly less in the renal failure group than the normal control group, indicating a reduction of baroreflex sensitivity in the setting of uraemia.
3. The pressor response to noradrenaline and angiotensin II was significantly less in the renal failure group whereas there was no difference in Δblood pressure on administration of arginine vasopressin.
4. It is concluded that diminished baroreflex sensitivity does not contribute to the pathogenesis of hypertension in uraemia by the hypothesized mechanism of allowing the pressor effect of endogenous pressor substances to go unbuffered.
Sleep apnoea in alcoholic patients after withdrawal
Authors: Tan E. T. H. , Lambie D. G. , Johnson R. H. , Robinson B. J. , Whiteside E. A. 
Published: August 2015

1. Respiration during sleep was studied in 16 withdrawn alcoholic patients and in 12 control subjects.
2. The alcoholic patients had increased numbers of central (P &lt; 0.01) and of obstructive (P &lt; 0.05) apnoea and of hypopnoea episodes (P &lt; 0.01) as compared with controls.
3. Significant positive associations were found between the frequencies of central apnoea (P &lt; 0.05) or hypopnoea (P &lt; 0.01) and clinical evidence of central nervous system damage in the alcoholic patients. Hypopnoea also showed a significant association with vagal neuropathy (P &lt; 0.05), assessed by tests of cardioreflexes.
4. We conclude that abnormal respiratory events are common in abstinent alcoholic patients and that they are likely to be at least partly related to nervous damage.
The effect of hypoglycaemia on visual function: a clinical and electrophysiological study
Authors: Harrad R. A. , Cockram C. S. , Plumb A. P. , Stone S. , Fenwick P. , Söunksen P. H. 
Published: August 2015

1. Disturbance of vision commonly accompanies hypoglycaemia. This study was designed to investigate the nature of the visual disturbance, the blood glucose threshold at which the disturbance occurred and the physiological basis.
2. Measurements were made of the corrected visual acuity, colour vision (100 Hue test), visual evoked potentials (VEP), electroencephalography (EEG) frequency analysis and psychometry (digit recall) during stepwise induction of controlled hypoglycaemia produced by an intravenous insulin infusion. Six male volunteers and five insulin-dependent diabetic subjects were studied.
3. During hypoglycaemia corrected visual acuity was unchanged. Colour vision was significantly impaired. Baseline VEP were normal in both groups but significantly prolonged during hypoglycaemia (mean increment 10.8 ms) and increased by &gt;5 ms in nine out of 11 subjects. Quantitative EEG analysis demonstrated slowing with a power density spectral shift from fast α to slow α, θ and δ which correlated with VEP latency and amplitude changes.
4. The findings have clinical implications. A deterioration in colour vision is likely to impair the ability to read reagent strips by eye. VEP measurements in diabetic patients are likely to be misleading if hypoglycaemia is present; EEG changes are a sensitive index of cortical dysfunction during hypoglycaemia and provide a theoretical basis for developing a portable device to detect early hypoglycaemia.
Effect of natural and synthetic atrial natriuretic factor on arterial blood pressure, natriuresis and cyclic GMP excretion in spontaneously hypertensive rats
Authors: Pang Stephen C. , Hoang Minh-Chau , Tremblay Johanne , Cantin Marc , Garcia Raul , Genest Jacques , Hamet Pavel 
Published: August 2015

1. The differential effects of extracted and synthetic atrial natriuretic factor (ANF) on arterial blood pressure, natriuresis, and cyclic GMP excretion were studied in normotensive (WKY) and spontaneously hypertensive (SHR and SHRSP) rats.
2. Atrial extracts or synthetic (101–126)-ANF decreased arterial blood pressure in all tested animals, but the blood pressure-lowering effect was more pronounced in hypertensive than in normotensive rats. ANF-induced diuresis and natriuresis were two- to three-fold higher in the hypertensive groups. However, a several-fold increase in total urinary cyclic GMP level after the infusion of ANF was essentially equal in the three groups.
3. Our data suggest that acute infusion of ANF reveals a defect of sodium and water handling in SHR. It is possible that this defect is located at the distal nephron, and is made apparent by the action of ANF on glomeruli via a cyclic GMP-induced vascular effect.
Mineralocorticoid escape during kallikrein inhibition
Authors: Overlack Axel , Bäcker-Kreutz Evita , Ressel Christa , Müller Hans-Michael , Kolloch Rainer , Stumpe Klaus-O. 
Published: August 2015

1. Kinins have been considered to be involved in the escape from the sodium retaining effects of mineralocorticoids. In a metabolic study in rats, the importance of the kallikrein-kinin system for sodium and potassium excretion was evaluated by aprotinin-induced kallikrein inhibition under basal conditions and during DOCA administration.
2. Kallikrein inhibition was accompanied by a transient sodium retention. The escape from the sodium retaining effect of DOCA was not affected. However, the DOCA-induced potassium loss was enhanced.
3. Kallikrein inhibition decreased urinary prostaglandin (PG) E2 and prevented the DOCA-induced rise in PGE2. Plasma renin activity was stimulated after 10 days of aprotinin administration.
4. The kallikrein-kinin system is not an important mediator of the escape phenomenon but it may play a role in the regulation of sodium and potassium excretion.
The ferritin content of normoblasts and megaloblasts from human bone marrow
Authors: Hodgetts J. , Peters S. W. , Hoy T. G. , Jacobs A. 
Published: August 2015

1. Erythroblasts were enriched from human bone marrow samples and fractionated on Percoll gradients according to maturity.
2. Heart-type and spleen-type ferritin was measured in each fraction by an immunoradiometric assay.
3. In normal marrow, heart-type ferritin content was higher in the early erythroblast fractions and fell with maturation. Spleen-type ferritin content showed no such consistent change.
4. Megaloblastic erythroblasts had a significantly higher ferritin content.
Effects of packed cell volume reduction on renal haemodynamics and the renin-angiotensin-aldosterone system in patients with secondary polycythaemia and hypoxic cor pulmonale
Authors: Wallis P. J. W. , Cunningham J. , Few J. D. , Newland A. C. , Empey D. W. 
Published: August 2015

1. Polycythaemia was corrected by erythrapheresis in ten patients with hypoxic cor pulmonale who were stable on regular diuretic therapy. Renal haemodynamics, renal function and the renin-angiotensin-aldosterone system were assessed before and afterwards.
2. Before erythrapheresis effective renal plasma flow (ERPF) was reduced (63% predicted) but glomerular filtration rate (GFR) was preserved (88% predicted) by a rise in filtration fraction (FF) (138% predicted). A negative correlation existed between ERPF and packed cell volume (r = −0.723; P &lt; 0.02) and also between ERPF and Paco2 (r = − 0.710; P &lt; 0.05). Polycythaemia was sufficient to maintain renal oxygen delivery (97% predicted).
3. After erythrapheresis systemic blood pressure, blood volume and blood viscosity all decreased. ERPF increased by 18% (P &lt; 0.02). FF fell by 11% (P &lt; 0.05) and GFR was unchanged. Renal oxygen delivery diminished by 25% (P &lt; 0.001).
4. Plasma renin activity was increased in five patients and plasma aldosterone increased in two patients before erythrapheresis. No sustained fall occurred in plasma renin activity or plasma aldosterone, possibly because the haemodynamic consequences of the procedure had opposing actions on renin secretion.
5. Although the reduction in FF would per se tend to enhance renal sodium and water excretion, a diuresis or natriuresis did not occur consistently.
Elevation of sodium levels in the cerebral ventricles of anaesthetized dogs triggers the release of an inhibitor of ouabain-sensitive sodium, potassium-ATPase into the circulation
Authors: Jandhyala Bhagavan S. , Ansari Ahmad F. 
Published: August 2015

1. The present studies are designed to determine whether a ouabain-sensitive inhibitor of Na+, K+−stimulated ATPase is released into the circulation when the Na+ levels are elevated in the cerebral ventricles in pentobarbital anaesthetized dogs. Na+−pump activity was estimated in the plantar and dorsal branches of the lateral saphenous veins by using the 86Rb-uptake method.
2. Infusion of the cerebral ventricles with the artificial cerebrospinal fluid (CSF) containing normal Na+ (0.15 mol/l) for over 120 min resulted in significant increases in only ouabain-sensitive 86Rb-uptake. In contrast, when the ventricles were perfused with the CSF containing high Na+ (0.3 mol/l) for similar periods, there were significant reductions in the ouabain-sensitive as well as in ouabain-insensitive 86Rb-uptake by the blood vessels.
3. Similar blood vessels from a separate group of dogs were incubated for 120 min in the plasma samples collected from the above groups in which normal or hypertonic Na+ solutions were infused. The data showed that ouabain-sensitive 86Rb-uptake (but not the insensitive component) was significantly inhibited only in those vessels which were incubated in the plasma samples that were obtained at 120 min after perfusion of the cerebral ventricles with CSF containing high Na+ (0.3 mol/l).
4. These studies have provided direct evidence which would suggest that the elevation of Na+ levels in the cerebral ventricles would precipitate the release of an inhibitor of the ouabain-sensitive Na+−pump into the circulation, perhaps due to an activation of Na+−sensitive and/or osmo-sensitive sites in the circumventricular organs. It is hypothesized that this humoral substance may be the same ‘natriuretic hormone’ which is released after acute expansion of circulating blood volume.
The effect of sodium bicarbonate on the flow-dependency of urinary prostaglandin excretion in man
Authors: Haylor J. , Lote C. J. , Thewles A. 
Published: August 2015

1. The influence of oral water loading on the excretion rate of prostaglandin (PG) E was investigated in healthy human subjects in a control study where the urine was acidic (pH 5.7) and after oral sodium bicarbonate, which made the urine mildly alkaline (pH 7.2). PGE was immediately extracted from urine and measured by a radioimmunoassay technique.
2. After sodium bicarbonate (5 g) the urinary PGE excretion rate was some three-fold higher (P &lt; 0.01) than in the control study, in the absence of any significant difference in the urine flow (approximately 80 ml/h).
3. In the control study (urine pH 5.7) the urinary PGE excretion rate increased significantly (P &lt; 0.01) as the urine flow rose in response to the oral fluid load. However, after sodium bicarbonate, PGE excretion did not alter after the fluid load despite a 10-fold increase in urine flow.
4. Since after bicarbonate administration PGE excretion is independent of urine flow, mildly alkaline urine may represent a condition under which renal PGE synthesis can be effectively assessed from measurements of urinary PGE excretion, in the presence of changes in urine flow.
5. In addition, the results are compatible with the hypothesis that, in man, PGE may be passively reabsorbed in the distal nephron, and a reduction in this reabsorption could contribute to or be responsible for the dependency of the excretion rate of PGE on urine flow.
Desensitization of platelet α2-adrenoceptors after short term infusions of adrenoceptor agonist in man
Authors: Jones C. R. , Giembcyz M. , Hamilton C. A. , Rodger I. W. , Whyte K. , Deighton N. , Elliott H. L. , Reid J. L. 
Published: August 2015

1. The effect of intravenous infusion of catecholamines and related drugs on human platelet α2-adrenoceptor number and function was investgated.
2. Short (60–120 min) infusions of catecholamines with α2 agonist activity in vivo produced attenuation of the platelet responses to adrenaline in vitro. This desensitization was specific for the adrenaline induced aggregatory response.
3. The maximum number of [3H]yohimbine binding sites on platelets was not altered by adrenaline infusion.
4. The ability of adrenaline to reduce platelet cyclic AMP levels was significantly reduced after the infusions.
5. Acute infusions of α2-adrenoceptor agonists may alter the coupling of the platelet α2-adrenoceptor to adenylate cyclase.
Evaluation of an isotope washout technique to measure skin vascular resistance and skin perfusion pressure: influence of age, site and arterial surgery
Authors: Duncan Henry J. , Faris Irwin B. 
Published: August 2015

1. A simplified isotope washout technique has been devised to calculate the skin perfusion pressure (SPP) and skin vascular resistance (SVR). This test is simple, requires inexpensive equipment and is well tolerated by patients.
2. SPP and SVR were calculated in 20 patients &lt;30 years of age, 13 patients ≥.30 years of age and in 15 patients with peripheral vascular disease (PVD). With increasing age the SPP and SVR were increased. The SPP was similar to the mean arterial pressure in normal individuals but was decreased in patients with PVD. The SPP is a useful indicator of the severity of the PVD.
3. The SPP and SVR were higher in the calf than in the foot. This is probably related to the decrease in pressure in the distal arterial tree.
4. SPP was increased by 110% and skin blood now by 190% by arterial reconstructive surgery. This test may be of use in assessing the effectiveness of arterial surgery.
Increased chemiluminescence of polymorphonuclear leucocytes from patients with progressive systemic sclerosis
Authors: Kovacs Iren B. , Thomas R. H. Meyrick , Mackay A. R. , Rustin M. H. A. , Kirby J. D. T. 
Published: August 2015

1. Chemiluminescence (CL) of whole blood and isolated polymorphonuclear leucocytes (PMN) from patients with systemic sclerosis (SS) and from age and sex matched controls was measured. CL was induced by the addition of particles (zymosan, latex beads), or phorbol myristate acetate (PMA) or chemotactic peptide (FMLP).
2. Whole blood CL (induced by PMA, zymosan or latex particles) was significantly greater in SS patients than in normal controls.
3. Isolated PMN CL (induced by PMA, FMLP or latex particles) was also significantly greater in the SS patients compared with controls.
4. Increased CL or PMN from patients with SS was mainly observed when luminol was used as amplifier (which detects hydrogen peroxide formation). In most cases, lucigenin-amplified CL of PMN from patients with SS (which detects the primary superoxide anion radical formation) did not differ from the controls.
5. Sera from patients with SS significantly increased both spontaneous and induced CL of normal PMN.
6. Enhanced excitability of PMN to phagocytosis-related stimuli may provide a mechanism for the (leucocyte-mediated) endothelial injury in SS.
The effect of cyclical hormonal changes on erythrocyte electrolyte transport mechanisms
Authors: Gallery Eileen D. M. , Bean Catherine , Grigg Roslyn , Saunders Douglas M. 
Published: August 2015

1. Electrolyte transport characteristics were examined in erythrocytes from 13 normal men and from two groups of women: (i) taking combined oral contraceptive preparations (O/C, n = 10), and (ii) ovulatory women (non-O/C, n = 10) pre- and post-ovulation, at the same time intervals (days 7–10 and days 15–18) during a menstrual cycle.
2. With rubidium (86Rb+) used as a potassium analogue, co-transport (ouabain-resistant, fruse-mide-sensitive 86Rb+ influx) values were found to be lowest in non-O/C women (28 ± se 2.5 nmol h−1 10−9 cells) and highest in men (56 ± 5.7, P &lt; 0.001), with results between the two in women taking O/C (42 ± 4.2, P &lt; 0.05 vs men, P &lt; 0.01 vs non-O/C). Passive 86Rb leak (frusemideand ouabain-resistant) was significantly lower in men (13 ± 1.6 nmol h−1 10−9 cells) than in both groups of women (non-O/C 29 ± 1.8, P &lt; 0.001; O/C 25 ± 1.2, P &lt; 0.001). There was no cyclical variation within either group of women.
3. Maximum ouabain binding (number of Na+,K+-ATPase units) was the same in all groups. Na+,K+-ATPase activity, as determined by ouabain-sensitive 86Rb influx, was the same in men and non-O/C groups, but was significantly suppressed in O/C compared with both men (P &lt; 0.01) and non-O/C women (P &lt; 0.05).
4. The differences found were not due to alterations in either progesterone or aldosterone, but could represent an androgenic effect in vivo of the 19-nortestosterone derivatives in combined oral contraceptive preparations.