bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calcium Accumulation and Calcium Binding by the Cell Membranes of Cardiomyocytes and Smooth Muscle of Aorta in Spontaneously Hypertensive Rats
Authors: Orlov S. N. , Postnov Yu. V. 
Published: August 2015

1. The ability of isolated membrane fractions of cardiomyocytes, aortic smooth muscle and erythrocytes from spontaneously hypertensive rats to bind calcium was investigated isotopically.
2. Plasma membranes of aortic smooth muscle and erythrocytes of spontaneously hypertensive rats possess a lower calcium-binding ability than preparations from normotensive controls.
3. Sarcoplasmic reticulum from the myocardium of spontaneously hypertensive rats had a lower ability to accumulate calcium.
4. Changes in the calcium-binding ability of the erythrocyte membrane of spontaneously hypertensive rats was related to the diminution of the amount of exchangeable calcium on the inner part of the membrane. The latter may be the cause of the increase of erythrocyte membrane permeability for sodium in spontaneously hypertensive rats and in patients with essential hypertension.
Increased Adrenaline, β-Adrenoreceptor Stimulation and Phospholipid Methylation in Pineal Gland of Spontaneously Hypertensive Rats
Authors: Saavedra J. M. 
Published: August 2015

1. In pineal glands of adult spontaneously hypertensive rats (Okamoto strain), dopamine levels increased 34%, adrenaline concentrations increased 152% and noradrenaline levels decreased by 26%, when compared with Wistar-Kyoto normotensive controls.
2. These results are consistent with the hypothesis of an increased uptake of peripheral adrenaline resulting in increased release of noradrenaline from pineal sympathetic nerves in hypertensive rats.
3. The activity of pineal N-acetyltransferase was increased fourfold in hypertensive rats, indicating increased stimulation of pineal β-adrenoreceptors.
4. Methylation of pineal membrane phospholipids was also increased (100-320%) in hypertensive rats.
5. These results indicate a correlation in vivo between increased β-adrenoreceptor stimulation and increased methylation of membrane phospholipids in the rat pineal gland, which could result in changes in membrane fluidity and affect the coupling of the β-adrenoreceptors to the adenylate cyclase.
Early Changes in Noradrenaline Content of Some Brain Nuclei in Spontaneously Hypertensive Rats
Authors: Le Quan-Bui Kim Hanh , Elghozi Jean-Luc , Devynck Marie-Aude , Meyer Philippe 
Published: August 2015

1. The noradrenaline content of individual brain nuclei was measured by using high-pressure liquid chromatography coupled with electrochemical detection.
2. This study was performed on spontaneously hypertensive rats during the development of hypertension (4 and 12 weeks) and also on deoxycorticosterone-salt hypertensive rats after 1 and 4 weeks of treatment.
3. In young spontaneously hypertensive rats a significant decrease in noradrenaline content was observed in some medullary and hypothalamic nuclei which are involved in cardiovascular regulation. No change was observed after deoxycorticosterone-salt treatment.
4. It is proposed that a change in adrenergic activity, restricted to brain cardiovascular centres, could represent a mechanism triggering spontaneous hypertension.
The Role of Endogenous Opiates in the Area Postrema Pressor Pathway
Authors: Szilagyi Julianna E. , Ferrario C. M. 
Published: August 2015

1. Intra-vertebral artery-administered angiotensin II acts at the area postrema to facilitate central sympathetic vasomotor activity. Recent evidence suggests a possible role of the opiate system in the mechanism of action of angiotensin II at the level of the brain stem.
2. In these experiments, we show that the morphine antagonist naloxone reduces significantly the magnitude of the pressor response to vertebral artery-infused angiotensin II.
3. Morphine, in contrast, doubled the peak of the vertebral response to identical doses of the peptide. Neither naloxone nor morphine affected the pressor responses to intravenously administered angiotensin II.
4. The data suggest that the endogenous opiate system in the medulla modulates the cardiovascular effects of angiotensin II at the level of the area postrema.
Central and Regional Normetadrenaline in Evaluation of Neurogenic Aspects of Hypertension: Aid to Diagnosis of Phaeochromocytoma
Authors: Dequattro V. , Sullivan P. , Foti A. , Bornheimer J. , Schoentgen Sarah , Versales Gilda , Levine D. , Kobayashi K. 
Published: August 2015

1. Free normetadrenaline concentrations in plasma of patients with phaeochromocytoma were elevated 20–1000-fold as compared with values in primary hypertensive subjects.
2. Spinal fluid normetadrenaline was 1.8-16% of the simultaneous plasma values in patients with phaeochromocytoma, whereas levels in spinal fluid exceeded those of plasma in primary hypertension.
3. Spinal fluid noradrenaline was 7.9-58% of simultaneous values of plasma noradrenaline in patients with phaeochromocytoma, whereas values in plasma and cerebrospinal fluid were similar in primary hypertension.
4. Plasma noradrenaline and normetadrenaline levels were both elevated in veins from regions subsequently found to harbour chromaffin tumours.
5. The excessive amounts of normetadrenaline produced in phaeochromocytoma enters plasma but not spinal fluid and can be used for diagnosis and localization of phaeochromocytoma.
Increased Sympathetic Activity and Blood Pressure in Young Asymptomatic Men with ‘Organic’ T-Wave Aberrations in the Electrocardiogram
Authors: Atterhog J.-H. , Eliasson K. , Hjemdahl P. 
Published: August 2015

1. Twelve asymptomatic young men with ‘primary’ T-wave aberrations in the electrocardiogram (group T) and 13 matched controls were subjected to a mental stress test, isometric exercise and a cold pressor test.
2. Plasma catecholamines and haemodynamics were studied.
3. Group T had signs of increased sympathetic activity at rest and enhanced sympatho-adrenal reactivity during stress.
4. Systolic blood pressure was consistently elevated in group T.
5. The T-wave aberrations may be explained by the increased sympathetic activity.
6. Several similarities exist between group T and borderline hypertensive subjects.
Is Substance P the Transmitter at the First Synapse of the Baroreceptor Reflex in Rats and Cats?
Authors: Haeusler G. , Osterwalder R. 
Published: August 2015

1. Substance P, injected into a lateral brain ventricle of urethane-anaesthetized rats, caused dose-dependent increases in blood pressure and heart rate.
2. By contrast, exposure of the obex region of the medulla oblongata to pieces of filter paper soaked in substance P-containing solution resulted in falls of blood pressure and heart rate in both rats and cats.
3. A more precise application of substance P to the first synapse of the baroreceptor reflex by micro-injection into defined areas of the nucleus of the solitary tract also led to an activation of the baroreceptor reflex.
4. Capsaicin, which is known to release substance P from primary afferents, mimicked the sympatho-inhibitory and cardiovascular effects of substance P when applied locally to the nucleus of the solitary tract.
5. The results are compatible with a transmitter or neuromodulatory role for substance P at the first synapse of the baroreceptor reflex.
Reno-Renal and Reno-Adrenal Reflexes in the Rat
Authors: Recordati G. , Genovesi S. , Cerati D. , Di Cintio R. 
Published: August 2015

1. Experiments were carried out to investigate whether the activation of renal chemoceptive receptors by natural stimuli might induce reflex alterations of efferent postganglionic activity to the ipsilateral kidney and preganglionic activity to the ipsilateral adrenal.
2. In anaesthetized rats with intact nervous system back-flow of urine and occlusion of the renal artery were accompanied by increments in efferent sympathetic activity both to the kidney and adrenal without concomitant changes in heart rate and blood pressure.
3. Greater excitatory responses in nerve activity to the same test stimuli were observed in rats with the spinal cord cut at C1.
4. These results indicate that the natural activation of renal chemoceptive receptors might induce reno-renal and reno-adrenal excitatory reflexes which are likely to be integrated at spinal and supraspinal levels.
Regional Blood Flows in High-Cardiac-Output Hypertension
Authors: Liard J. F. 
Published: August 2015

1. Mean arterial pressure, cardiac output (electromagnetic flow-meter) and regional blood flows (15 μm radioactive microspheres) were measured repeatedly in eight dogs receiving a salt and water load after renal mass reduction as well as in six control animals.
2. As previously observed, hypertension developed in the salt-loaded dogs with an initial increase in cardiac output followed by a secondary rise in total peripheral resistance.
3. Much of the early increase in cardiac output was distributed to the skeletal muscle vascular bed.
4. Total peripheral resistance changes did not reflect the resistance of individual vascular beds in the early stages of salt and water load hypertension; indeed, resistance in the muscle vascular bed was decreased and that in the splanchnic area and the bone increased on the first day of salt and water load when total peripheral resistance was unchanged.
Alterations in Cardiac Function and Cardiopulmonary Blood Volume in Chronic Sodium Depletion in Dogs
Authors: Lynn M. P. , Fouad F. , Cook S. A. , Napoli Carmen A. , Ferrario C. M. 
Published: August 2015

1. Chronic sodium depletion in dogs is associated with a blunting of the pressor response to carotid occlusion. After section of the vagus nerves this pressor response reverts to normal although atropine is without effect, suggesting a possible role for increased activity of cardiopulmonary vagal afferents in suppressing sympathetic outflow. Since increases in central blood volume stimulate vagal afferents, cardiopulmonary haemodynamics were studied by radioisotope dilution before and after 3 and 4 weeks of dietary sodium restriction together with frusemide.
2. Sodium depletion was associated with significant decreases in cardiac output, ejection fraction and total blood volume; the cardiopulmonary blood volume increased but the change was not statistically significant (P&lt;0.2). These changes were accompanied by a significant increase in the ratio cardiopulmonary blood volume/total blood volume and a decrease in the ratio cardiac output/cardiopulmonary blood volume.
3. Results indicate that sodium depletion may be accompanied by a paradoxical translocation of blood to the cardiopulmonary region in part due to depressed ventricular performance.
Total Body Potassium Falls with Age
Authors: Rajagopalan B. , Thomas G. W. , Beilin L. J. , Ledingham J. G. G. 
Published: August 2015

1. Plasma volume, 24 h urine sodium and total body potassium were similar among 89 previously untreated patients with mild hypertension and 89 control subjects matched for age and sex.
2. Total body potassium correlated with renin activity in both hypertensive patients and controls.
3. Renin activity and total body potassium fell significantly with age in both groups.
4. The relationship between renin and total body potassium was no longer present when the effects of age were allowed for in a partial correlation.
β-Adrenoreceptor-Blocking Agents and the Blood-Brain Barrier
Authors: Cruickshank J. M. , Neil-Dwyer G. , Cameron M. M. , McAinsh J. 
Published: August 2015

1. Sixteen neurosurgical patients received (oral) β-adrenoreceptor-blocking agents (β-receptor blockers) for 3–22 days.
2. Lipophilic β-receptor blockers (propranolol) and metoprolol appeared in cerebrospinal fluid at concentrations similar to the free drug plasma concentration.
3. Cerebrospinal fluid concentrations of β-receptor blockers were poor predictors of brain concentrations
4. Both lipophilic β-receptor blockers appeared in high concentrations in the brain: the brain/plasma ratio was approximately 15:1.
5. Hydrophilic atenolol appeared at low concentrations in brain tissue (about 20 times lower than the lipophilic β-receptor blockers): the brain/plasma ratio was approximately 0.1:1.
6. Central nervous system-related side effects associated mainly with lipophilic β-receptor blockers possibly result from high brain tissue concentrations.
α- and β-Adrenoreceptor-Mediated Control of Brain Noradrenaline Neurons and Antihypertensive Therapy
Authors: Svensson T. H. , Almgren O. , Dahlof C. , Elam M. , Engberg G. , Hallberg H. , Thoren P. 
Published: August 2015

1. The central noradrenergic nucleus locus coeruleus seems to participate in arousal reactions and cardiovascular modulation. Using single cell recording techniques and biochemical assays, we have studied locus coeruleus neuronal regulation and its interaction with antihypertensive treatments.
2. Acute (5 μg/kg intravenously) or chronic clonidine treatment (2 μg/ml in drinking water for 2 weeks) significantly reduced locus coeruleus neuronal activity, probably via activation of α2-receptors within the nucleus. Termination of the chronic regimen increased the noradrenaline cell firing rates above baseline, a finding possibly related to the withdrawal syndrome.
3. In spontaneously hypertensive rats the activation of locus coeruleus neurons by yohimbine, an α2-receptor antagonist, was increased compared with that in normotensive (Wistar-Kyoto) control rats, implying an altered α2-receptor-mediated control of the central noradrenaline neurons.
4. Chronic treatment with dl-propranolol (5 or 10 mg/kg daily for 1 week) but not d-propranolol or acutely given dl-propranolol significantly reduced neuronal activity in the locus coeruleus, an effect which may relate to mental and cardiovascular actions of β-receptor-blocking drugs.
5. In contrast, chronically given salbutamol, a β2-receptor agonist (5 mg/kg subcutaneously for 2 weeks), increased brain noradrenaline utilization. Thus β-receptors probably participate in the control of brain noradrenaline neurons.
Influence of Breath Holding at Total Lung Capacity on Maximal Expiratory Flow Measurements
Authors: Higenbottam T. , Clark T. J. H. 
Published: August 2015

1. Forced exhalations performed from volumes below total lung capacity, so-called partial expiratory flow-volume curves, are suggested to be more sensitive in detecting airways bronchoconstriction than maximal expiratory flow-volume curves begun at total lung capacity.
2. In eight healthy men both maximal and partial expiratory flow-volume curves were measured where breath was held at total lung capacity or 70% of vital capacity respectively, for either 0 or 15 s before performing the forced exhalation. An histamine aerosol was used to provoke bronchoconstriction.
3. The results showed that the 15 s breath hold caused greater reduction in expiratory flow rates after histamine for both maximal and partial expiratory flow-volume curves than either manoeuvres performed with no breath hold.
4. A breath hold of 15 s at total lung capacity appeared to make the maximal expiratory flow-volume curve as sensitive as a partial expiratory flow-volume curve in detecting the response to histamine as well as providing measurements of forced expiratory volume in 1 s and vital capacity. Forced spirometry after a 15 s breath hold at total lung capacity therefore provides an easy and sensitive technique for detecting bronchoconstriction.
Renin in the Mouse Kidney Has a Molecular Weight of 40 000
Authors: Poulsen K. , Nielsen A. H. 
Published: August 2015

1. Mouse kidney was homogenized in a mixture of serine-metallo- and thiol-enzyme inhibitors. The homogenate proteins were separated with respect to size and charge by gel filtration, agarose electrophoresis and polyacrylamide-gel electrophoresis.
2. Renin was localized by its enzymatic activity by using the antibody trapping radioimmunoassay for angiotensin I, before and after acid treatment and limited proteolysis. Renin was also localized by its antigenic properties by using antirenin antibodies elicited against pure mouse submaxillary renin. The antibody cross-reacted fully with mouse kidney renin and with high-molecular-weight renin forms in mouse plasma.
3. In the kidney only fully enzymically active 40 000 renin could be detected enzymically and antigenically. No high-molecular-weight renin or inactive renin was demonstrable.
4. Two electrophoretically different renin forms were seen in accordance with renin being a glycoprotein. They were both fully enzymically active with identical specific enzymatic activities.
5. The mouse kidney renin had a specific enzymatic activity identical with that of pure mouse submaxillary renin, being 0.4 Goldblatt unit/μg.
Effect of a Long-Term Fat-Modified Diet on Serum Lipoprotein Levels of Cholesterol and Triglyceride in Patients on Home Haemodialysis
Authors: Wass V. J. , Jarrett R. J. , Meilton V. , Start M. K. , Mattock M. , Ogg C. S. , Cameron J. S. 
Published: August 2015

1. Changes in serum total and lipoprotein fraction triglyceride and cholesterol levels were studied in 24 adults on home haemodialysis. Half the patients were randomly allocated to a low cholesterol (mean 200 mg/day), fat-modified diet (mean polyunsaturated/saturated fat ratio of 1.0 with a mean of 43% of the total energy content derived from fat).
2. Before dietary manipulation, triglyceride levels in all lipoprotein fractions were significantly higher (P &lt; 0.02) than in a control group of age and sex matched normal subjects. Total cholesterol, very-low-density-lipoprotein (VLDL) and low-density-lipoprotein (LDL) cholesterol were also significantly raised (P &lt; 0.02), but high-density-lipoprotein (HDL) cholesterol was normal. In the patients on a fat-modified diet triglyceride levels did not alter in any of the lipoprotein fractions. Total cholesterol and LDL cholesterol levels fell significantly into the normal range (P &lt; 0.002 and &lt; 0.001 respectively) but VLDL and HDL cholesterol levels did not change.
3. Hypertriglyceridaemia is the most common lipid abnormality in patients with renal failure and a long-term fat-modified diet is, therefore, of limited therapeutic importance in these patients unless there is a low HDL/LDL cholesterol ratio.
Effect of Hydrochlorothiazide on 1,25-dihydroxyvitamin D3-induced Changes in Calcium Metabolism in Experimental Hypoparathyroidism in Rats
Authors: Rizzoli R. , Hugi K. , Fleisch H. , Bonjour J.-P. 
Published: August 2015

1. Chronic administration of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] can normalize plasma calcium in human hypoparathyroidism and in thyroparathyroidectomized animals. The effect of 1,25(OH)2D3 on plasma calcium is associated with an increase in urinary calcium excretion. In an attempt to prevent this increase, thyroparathyroidectomized rats receiving 1,25(OH)2D3 were also treated with hydrochlorothiazide for 9–11 days.
2. Calcium clearance studies show that hydrochlorothiazide stimulated the tubular reabsorption of calcium in thyroparathyroidectomized rats treated with 1,25(OH)2D3.
3. Calcium balance and kinetic studies indicated that hydrochlorothiazide decreased 1,25(OH)2D3-induced hypercalciuria in thyroparathyroidectomized rats. Hydrochlorothiazide did not affect the 1,25(OH)2D3-induced increase in plasma calcium. The hypocalciuric effect of hydrochlorothiazide was not associated with significant changes in calcium deposition into or release from bone.
4. In thyroparathyroidectomized rats treated with 1,25(OH)2D3 the hypocalciuric effect of hydrochlorothiazide was associated with a fall in intestinal calcium absorption. Overall, the calcium balance was unaffected.
5. Thus it appears that hydrochlorothiazide reduces the 1,25(OH)2D3-induced hypercalciuria in parathyroid hormone-deficient animals by decreasing intestinal calcium absorption.
Despite the decreased absorption, hydrochlorothiazide does not reduce the 1,25(OH)2D3-induced increase in plasma calcium.
Local Regulation of Blood Flow in Subcutaneous Tissue in Patients with Acute Myocardial Infarction
Authors: Skagen K. , Henriksen O. , Amtorp O. , Fog-Møller F. , Lam H. 
Published: August 2015

1. Local regulation of subcutaneous blood flow in the forearm was studied in the acute phase of myocardial infarction. Blood flow was measured by the local 133Xe-washout technique.
2. Plasma concentrations of noradrenaline and adrenaline were increased on day 1, suggesting an increase in sympathetic neuronal activity, but gradually returned to normal thereafter.
3. Subcutaneous blood flow on day 1 was far below normal (38%) and steadily increased to reach normal at day 7 after coronary occlusion. The sympathetic vasoconstrictor activity that caused the initial reduction in flow could be blocked by proximal nervous blockade, increasing the subcutaneous blood flow by 130, 63 and 14% on days 1, 3 and 7 respectively after coronary occlusion. A normal response to decrease in arterial perfusion pressure was observed, suggesting that intrinsic vascular reactions responsible for autoregulation of blood flow were not affected by the increase in sympathetic vasoconstrictor activity. The vasoconstrictor response to increase in venous transmural pressure could not be demonstrated on day 1 after coronary occlusion but gradually reappeared during the following days.
4. Abolition of the vasoconstrictor response is most likely to be due to a centrally elicited increase in sympathetic activity, as a normal vasoconstrictor response was obtained after proximal nervous blockade. Thus the local sympathetic reflex mechanism underlying the vasoconstrictor response appears to be suppressed by a centrally elicited increase in sympathetic discharge rate.
Tubular Handling of Phosphate along the Nephron of Thyroparathyroidectomized Rats Injected with Ethane-1-Hydroxy-1,1-Diphosphonate
Authors: Mühlbauer R. C. , Bonjour J.-P. , Fleisch H. 
Published: August 2015

1. Previous studies have shown that in thyroparathyroidectomized rats injection of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) at doses that inhibit bone mineral retention (0.16 mmol = 10 mg of phosphorus/kg body wt. per day subcutaneously) leads to a decrease in the net tubular reabsorption of phosphate.
2. In the present work the tubular response to EHDP (0.16 mmol/kg body wt.) injected subcutaneously for 9 days has been localized by free-flow micropuncture in thyroparathyroidectomized rats.
3. The results show that the net tubular reabsorption of phosphate along the first portion of the (early) proximal tubule was markedly depressed in the EHDP-injected thyroparathyroidectomized rats compared with that in the pair-fed thyroparathyroidectomized control animals. In this latter group the delivery of phosphate to the distal tubule was larger than in the final urine, confirming previous reports. In the EHDP-injected thyroparathyroidectomized rats no difference in delivery of phosphate was found between the distal tubule and the final urine, suggesting that diphosphonate inhibited net reabsorption of phosphate in the terminal nephron.
4. The sites of the EHDP-induced changes in the tubular handling of phosphate were similar to those previously determined for the adaptive response to an increase in the supply of phosphate.
Effect of Head-Up Tilt on Subcutaneous Blood Flow during the Course of Acute Myocardial Infarction
Authors: Skagen K. 
Published: August 2015

1. Central and local regulation of subcutaneous blood flow in the forearm was studied in the acute phase of myocardial infarction.
2. Blood flow was measured by the local 133Xe-washout technique.
3. The vasoconstrictor response to increase in venous transmural pressure was not present on day 1 after coronary occlusion but gradually recurred during days 2, 3 and 7.
4. Passive 30° head-up tilt induced a vasoconstriction in subcutaneous tissue. There was no difference in this response at any time during the course of acute myocardial infarction. The vasoconstriction could be blocked by proximal nervous blockade.
5. Thus a decrease in baroreceptor activity induced by head-up tilt enabled a marked neurogenically mediated vasoconstriction in subcutaneous tissue, indicating that orthodromic impulse activity in sympathetic fibres can be further increased even on day 1 of acute myocardial infarction.