bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Non-Invasive γ-Camera Technique for the Measurement of Intrarenal Flow Distribution in Man
Authors: Gruenewald S. M. , Nimmon C. C. , Nawaz M. K. , Britton K. E. 
Published: August 2015

1. A new method, based on the transit time of o-iodohippurate sodium (Hippuran) through the kidney, is proposed as an accurate non-invasive means of measuring the intrarenal flow distribution in man.
2. Data from [123I]Hippuran γ-camera renography are utilized in this method which employs region of interest selection, deconvolution, cross-correlation and curve subtraction to obtain the spectrum of transit times through the cortical and juxtamedullary nephrons.
3. In 12 normal subjects the mean percentage cortical flow was 83.9% (sem 0.7%) which is approximately the anatomical proportion of cortical nephrons in the human kidney.
4. Cortical flow as a percentage of total was significantly reduced in 21 hypertensive patients, all of whom had no evidence of primary renal disease (mean 74.6%, sem 1.5%).
5. In both the normotensive and hypertensive groups there was a good correlation between the results obtained from the left and right kidneys of the same patient showing the parallel physiological response of the two kidneys (mean difference 4%, P &lt; 0.001).
6. Reduction in the distribution of flow to the cortical nephrons in the essential hypertensive patients supports the hypothesis that renal autoregulation is important in this syndrome.
Urine Free Dopamine in Normal Primigravid Pregnancy and Women Taking Oral Contraceptives
Authors: Perkins C. M. , Hancock K. W. , Cope G. F. , Lee M. R. 
Published: August 2015

1. Urine free dopamine was estimated at predetermined points of the menstrual cycle in normal volunteer subjects and in women taking a combined oral contraceptive.
2. There was no alteration in 24 h urine dopamine during the normal menstrual cycle but, in contrast, combined oral contraceptives produced a fall which recovered premenstrually.
3. In 19 primigravid subjects 24 h urine free dopamine was estimated at monthly intervals throughout pregnancy and at the time of the postnatal examination.
4. Urine dopamine was elevated throughout pregnancy when compared with postnatal values. Women receiving an oral progestogen contraceptive at the time of the postnatal examination showed a further fall in urine dopamine.
Methods to Assess Breathlessness in Healthy Subjects: A Critical Evaluation and Application to Analyse the Acute Effects of Diazepam and Promethazine on Breathlessness Induced by Exercise or by Exposure to Raised Levels of Carbon Dioxide
Authors: Stark R. D. , Gambles S. A. , Lewis J. A. 
Published: August 2015

1. Methods were devised and evaluated for inducing breathlessness by submaximal graded exercise in healthy subjects while objective measurements of cardiorespiratory function were made. Breathlessness was assessed with serial visual analogue scales (VAS), but with various measures to enhance repeatability.
2. A high level of reproducibility was obtained in spite of the subjective nature of the assessment. Individual responses were described by the relationship between breathlessness and ventilation. The sensitivity of the method was demonstrated by the use of inspiratory resistances which disturbed this relationship and caused greater breathlessness for a given level of ventilation.
3. These methods were applied to six healthy subjects to analyse the effects of acute doses of diazepam and promethazine on breathlessness induced by graded exercise or by rebreathing carbon dioxide in a double-blind study.
4. During exercise, diazepam and promethazine did not reduce breathlessness, although there was a minor trend with promethazine. During exposure to elevated levels of carbon dioxide, diazepam and promethazine had no effect on breathlessness. Diazepam and promethazine produced similar levels of sedation, but neither drug had significant effects on the ventilatory response to carbon dioxide. These preliminary findings contrast with those reported for chronic diazepam in ‘pink puffers’.
5. Raised levels of carbon dioxide caused greater breathlessness in relation to ventilation than did exercise.
Direct Measurement of the Hepatointestinal Extraction of Zinc in Cirrhosis and Hepatitis
Authors: Keeling P. W. N. , Ruse W. , Bull J. , Hannigan B. , Thompson R. P. H. 
Published: August 2015

1. 65Zn was injected intravenously during transjugular liver biopsy and, from simultaneous hepatic and peripheral venous blood samples, hepatointestinal 65Zn extraction was calculated. Hepatic zinc content was measured in biopsy specimens.
2. On the same occasion samples of liver tissue were taken and their zinc content was measured by atomic absorption spectrophotometry.
3. Seven patients with cirrhosis had significantly lower hepatic zinc content and hepatointestinal zinc extraction than six control patients with mild liver disease. Six patients with chronic hepatitis had a mean hepatointestinal zinc extraction higher than control patients, whereas their mean hepatic zinc content was lower, although the former difference did not achieve statistical significance.
4. These results demonstrate that hepatointestinal extraction of zinc is impaired in cirrhosis, but not in chronic hepatitis.
Abnormal Calcium Handling by Isolated Cardiac Plasma Membrane from Spontaneously Hypertensive Rats
Authors: Pernollet Marie-Gabrielle , Devynck Marie-Aude , Meyer P. 
Published: August 2015

1. Calcium handling by heart sarcolemmal vesicles from young spontaneously hypertensive rats (SHR) and normotensive Wistar—Kyoto (WKY) control rats were compared.
2. Calcium binding was significantly altered in SHR membranes at the physiological cytosolic Ca2+ concentrations which occur in resting and excited cells.
3. ATP-dependent calcium accumulation occurred at a higher rate in SHR than in WKY rat membrane vesicles.
4. Na+-dependent calcium extrusion of loaded vesicles was higher in SHR than in WKY rat membrane vesicles.
5. These alterations may play a significant role in the pathogenesis of hypertension.
Urinary Crystal Growth: Effect of Inhibitor Mixtures
Authors: Werness P. G. , Bergert Jan H. , Lee Karen E. 
Published: August 2015

1. The crystal growth inhibitory activity of mixtures of known inhibitors and of mixtures of known inhibitors with normal urine was determined in calcium oxalate monohydrate and hydroxyapatite seeded crystal growth systems.
2. The inhibitory activity of the mixtures was compared with the measured activity of the individual components of the mixtures. All mixtures had inhibitory activity equal to the sum of the activities of their components, with the exception of RNA/urine mixtures in the calcium oxalate monohydrate system.
3. RNA/urine mixtures had inhibitory activity toward calcium oxalate monohydrate crystal growth which was less than would be predicted from the activity of the RNA and of the urine which were added. This reduced inhibitory activity was shown to be due probably to hydrolysis of RNA by the ribonuclease activity normally present in urine.
4. The results of these experiments make it possible to determine quantitatively the contribution of various naturally occurring urinary crystal growth inhibitors to the total measured inhibition observed in urine.
Paraventricular—Suprachiasmatic Lesions Prevent Salt-Induced Hypertension in Dahl Rats
Authors: Azar Silvia , Ernsberger P. , Livingston Suzanne , Azar P. , Iwai J. 
Published: August 2015

1. We studied the effects that lesions produced in the paraventricular and suprachiasmatic nuclei and intervening periventricular area had on 24 h mean circadian blood pressures in Dahl salt-sensitive and -resistant rats and their sham-operated controls. We measured blood pressures while the animals were on a low salt diet and after 1, 5 and 13 weeks of 8% NaCl diet.
2. Salt-sensitive rats with lesions had lower blood pressures than salt-sensitive sham-operated controls at all points of the study. In contrast, identical lesions in salt-resistant rats produced a transient pressor response to the diet. Twenty-four hour mean heart rate, determined after 13 weeks of 8% NaCl intake, was low only in salt-sensitive rats with lesions. Sodium intake and excretion per kg of body weight, as well as plasma sodium concentrations, were similar in all groups.
3. We conclude that the anteromedial hypothalamic area, which includes the paraventricular nucleus, the suprachiasmatic nucleus and the intervening periventricular area, participates in the development of Dahl hypertension. We suggest that a multifactorial mechanism is involved: (a) the facilitatory role of this region in ACTH release, (b) this region's participation in the baroreceptor reflex via vasopressinergic efferents to the nucleus of the tractus solitarius, and (c) the roles of the paraventricular and suprachiasmatic nuclei in the regulation of salt and water balance.
Effect of Adrenalectomy on the Development of Isolation-Induced Hypertension in Rats
Authors: Gardiner S. M. , Milmer K. E. , Bennett T. 
Published: August 2015

1. Male Wistar rats develop systolic arterial hypertension when housed in glass metabolism cages. The present experiments were designed to investigate the involvement of the adrenal glands in this form of hypertension.
2. Rats were bilaterally adrenalectomized and maintained by either salt supplementation (1% sodium chloride solution instead of tap water to drink) or steroid replacement (corticosterone solution in the drinking water).
3. Adrenalectomized rats treated as above did not develop hypertension in response to isolation, whereas sham-operated rats (drinking either 1% saline or tap water) did.
4. Hypertension in the sham-operated rats was not accompanied by a renal retention of sodium and water.
5. It is concluded that increased adrenal activity is involved in the development of isolation-induced hypertension, but not by causing a fluid retention and hence volume expansion. The relative contributions of adrenal medullary and cortical activity remain to be determined.
Accentuated Hypotensive Effect of Sodium Nitroprusside in Man after Captopril
Authors: Jennings G. L. , Gelman J. S. , Stockigt J. R. , Korner P. I. 
Published: August 2015

1. The effects of graded intravenous infusions of sodium nitroprusside on resting blood pressure and heart rate and on the reflex changes in these variables evoked by a standardized Valsalva manoeuvre were studied in six normal subjects. The effects of nitroprusside on the above variables were also studied after pre-treatment with captopril, to allow assessment of the role of angiotensin II.
2. Nitroprusside given in doses ranging from 7.5 to 150 μg/min elicited dose-related decreases in resting blood pressure and rise in heart rate and in plasma renin activity (PRA). After pretreatment with captopril, nitroprusside could not be given at doses above 60 μg/min without producing an unacceptable fall in blood pressure. The rise in heart rate in response to a given dose of nitroprusside was little altered after captopril.
3. Blood pressure and heart rate were studied during the last 10 s of the Valsalva manoeuvre. Before captopril the normal response (maintenance of blood pressure with tachycardia) was not altered by any dose of nitroprusside. Captopril alone also had no effect on the response but, with captopril plus high dose nitroprusside, mean arterial pressure during the manoeuvre decreased significantly, indicating impairment of reflex constrictor response.
4. These findings support the proposition that the angiotensin II response normally limits the fall in blood pressure during vasodilator therapy. We conclude that the greater fall in blood pressure and the impaired constrictor response to the Valsalva manoeuvre during nitroprusside infusion at moderate doses, in the presence of captopril, is due to the effect of the latter on the renin—angiotensin system.
5. A practical consequence of the present findings is that combined use of captopril and arterial vasodilators requires reduction in the dose of the latter drug. Awareness of this interaction may avert hypotension and could also allow nitroprusside infusion for longer periods without toxicity.
Chemical Denervation Does Not Affect the Medial Hypertrophy and Increased Calcium Sensitivity of Mesenteric Resistance Vessels from Spontaneously Hypertensive Rats
Authors: Mulvany M. J. , Korsgaard N. , Nyborg N. , Nilsson H. 
Published: August 2015

1. The properties of isolated 150-μm mesenteric resistance vessels from chemically denervated 5-month spontaneously hypertensive and normotensive Wistar—Kyoto rats have been examined.
2. Chemical denervation reduced the blood pressure of both strains of rats, but the denervated spontaneously hypertensive rats were still hypertensive with respect to their denervated Wistar—Kyoto controls.
3. Chemical denervation did not affect the morphological characteristics or calcium sensitivity of the resistance vessels.
4. The results suggest that the media hypertrophy and increased calcium sensitivity seen in resistance vessels from non-denervated spontaneously hypertensive rats are intrinsic defects unrelated to either blood pressure or neurogenic influences.
A Comparison of Physical Characteristics of Active Renin Isolated from Aorta, Plasma and Kidney of the Rat
Authors: Barrett J. D. , Eggena P. , Krall J. F. , Sambhi M. P. 
Published: August 2015

1. Renin-like enzymes have been isolated from aorta, plasma and kidney tissue of the rat. The enzymes have been compared with respect to pH optima, molecular weight and isoelectric points.
2. Two distinct molecular-weight forms were isolated from plasma. The high-molecular-weight enzyme (mol. wt. &gt; 150 000) appeared to be homogeneous with respect to isoelectric point (pI = 5.3), whereas the dominant lower-molecular-weight form (mol. wt. 44 000) demonstrated isoelectric heterogeneity.
3. The renin-like enzyme isolated from aortic tissue has mol. wt. 44 000 and also demonstrated isoelectric heterogeneity (pI = 5.0, 5.3). Plasma renin was significantly reduced after bilateral nephrectomy (30 h); however, the activity and relative proportions of the two aortic enzymes were not significantly altered.
4. Renin, isolated from kidney homogenates, either in the presence or absence of a variety of proteolytic enzyme inhibitors, had a significantly lower molecular weight (38 000) than the plasma enzyme but demonstrated a similar pattern of isoelectric heterogeneity.
5. in contrast with renin extracted from kidney, approximately 30% of the renin released from kidney cortical slices into Krebs-Ringer bicarbonate had mol. wt. 44 000. Only the 38 000 mol. wt. form was detected after storage of this medium and no change in total renin activity was evident. This suggests that the 38 000 mol. wt. form may be a methodological artifact due to the release of other proteolytic enzymes.
6. With homologous substrate, all fractionated enzymes showed a pH optimum between pH 7.0 and 7.5.
7. The present study indicates that the predominant form of renin released from rat kidney into blood has mol. wt. 44 000. The microheterogeneity of the plasma enzyme with respect to isoelectric point is similar to that of kidney renin. One form of renin (mol. wt. 44 000, pI = 5.0) may be common to kidney, plasma and aorta. The second aortic enzyme (pI = 5.3), however, may be of local origin.
Partial Replacement of Sodium by Potassium in the Diet Restores Impaired Noradrenaline Inactivation and Lowers Blood Pressure in Stroke-Prone Spontaneously Hypertensive Rats
Authors: Dietz R. , Schömig A. , Rascher W. , Strasser R. , Ganten U. , Kübler W. 
Published: August 2015

1. Partial replacement of sodium by potassium in the diet attenuates the rise in blood pressure in stroke-prone spontaneously hypertensive rats (SHR-SP).
2. The blood pressure-lowering effect of potassium cannot be ascribed to a reduction in intravascular volume.
3. The increased dietary intake of potassium leads to a reduced stimulation of the sympathoneuronal and sympathoadrenal system by cold compared with the response of sodium-loaded rats.
4. The impaired inactivation of noradrenaline observed in sodium-loaded SHR-SP is improved in SHR-SP on a potassium-substituted diet.
5. It is concluded that changes in dietary intake of sodium and potassium modulate sympathetic activity and the metabolism of noradrenaline, both of which are related to the development of hypertension in SHR-SP.
Peritubular Interaction of Unconjugated Bilirubin in Isolated Perfused Rat Kidney
Authors: Elias Maria Monica , Comin E. J. , Galeazzi Susana , Garay E. A. Rodriguez 
Published: August 2015

1. the interaction of unconjugated bilirubin with peritubular cell membranes of the rat kidney was studied by means of an isolated rat-kidney preparation applying the multiple-indicator-dilution technique.
2. Inulin was used as an extracellular marker and p-aminohippuric acid as a model of organic anion that interacts with the peritubular membrane.
3. A single renal artery injection of a mixture containing inulin and unconjugated bilirubin was followed by the appearance of the two compounds in the venous effluent. the unconjugated bilirubin curve was always under the curve of inulin and its mean transit time was always less than that for inulin.
4. the cumulative venous recovery of inulin was higher than that of unconjugated bilirubin.
5. When unconjugated bilirubin uptake was plotted against the injected dose of pigment the relationship suggested a saturation phenomenon.
6. the recovery of p-aminohippuric acid was significantly increased when unconjugated bilirubin was added.
7. the results provide evidence for the interaction of unconjugated bilirubin with the peritubular cell membranes of rat kidney.
Kassinin and Substance P Stimulate Somatostatin Release in the Rat
Authors: Güllner H.-G. , Harris Virginia , Unger R. H. 
Published: August 2015

1. the effect of the tachykinin dodecapeptide kassinin, which has been extracted from the skin of several African frogs, on somatostatin release was examined in the rat and compared with that of the neuropeptide substance P.
2. Equimolar doses of the two peptides were injected intravenously and the animals killed at specified intervals after injection. Somatostatin was measured by a specific radioimmunoassay.
3. Kassinin and substance P had no effect when given in low doses (0.1 and 1.0 μg). However, when administered in a dose of 10.0 μg, both peptides significantly increased plasma somatostatin, by 31 and 22% respectively.
4. These findings suggest that kassinin and substance P have common endocrine actions. the effect on somatostatin release may be specific for tachykinins, since other neuropeptides such as the enkephalins have no effect.
Possible Relationship between Psycho-Emotional Factors and Haemodynamic Patterns in the Pathogenesis of Mild Blood Pressure Elevation
Authors: Jern S. , Sivertsson R. , Hansson L. 
Published: August 2015

1. Psycho-emotional profiles were compared with invasive haemodynamic findings in a population sample of 37 young men (mean age 27 years) with mild blood pressure elevation and in 21 matched normotensive controls.
2. In comparison with normotensive controls, subjects with hyperkinetic blood pressure elevation had higher irritability levels, more guilt feelings and more psychic distressful symptoms.
3. In subjects with blood pressure elevation and normokinetic circulation structural vascular changes were found, and their psycho-emotional profiles showed high irritability levels but not significantly increased guilt or anxiety.
4. These results indicate a relationship between psychological factors and haemodynamic patterns in mild blood pressure elevation. A psychosomatic aetiology in hyperkinetic blood pressure elevation is suggested, and the psychological findings are compatible with a gradual development from hyperkinetic to normokinetic blood pressure elevation.
Vasopressin-Induced Increase in Total Peripheral Resistance in Deoxycorticosterone Acetate Hypertensive Rats is Buffered by the Baroreceptor Reflex
Authors: Rascher W. , Lang R. E. , Taubitz M. , Meffle H. , Unger TH. , Ganten D. , Gross F. 
Published: August 2015

1. The role of arginine-vasopressin (AVP) in the maintenance of high blood pressure in rats with deoxycorticosterone acetate (DOCA) hypertension was investigated.
2. Plasma concentrations of AVP were significantly elevated in DOCA hypertensive rats compared with normotensive control rats, whether or not they received 1% sodium chloride solution or demineralized water to drink.
3. The specific antagonist of the vasopressor response to AVP, d(CH2)5VDAVP (100 μg/kg intravenously), significantly increased cardiac output and decreased total peripheral resistance, but had no effect on mean arterial pressure in DOCA hypertensive rats. No changes of mean arterial pressure, cardiac output and total peripheral resistance were observed in the normotensive control groups after d(CH2)5VDAVP.
4. After sino-aortic baroreceptor deafferentation, d(CH2)5VDAVP decreased mean arterial pressure in DOCA—salt hypertensive rats, but not in the control groups.
5. It is concluded that elevated circulating AVP causes vasoconstriction in DOCA hypertensive rats. The AVP-induced increase in total peripheral resistance is counter-regulated by an activation of the baroreceptor reflex and subsequent reduction in cardiac output.
Adrenaline-Induced Hypertension in Rats
Authors: Tung L.-H. , Rand M. J. , Majewski H. 
Published: August 2015

1. Rats implanted with osmotic minipumps delivering adrenaline intraperitoneally at the rate of 2.9 nmol/h had significantly higher systolic and diastolic pressures from days 2 to 6 after implantation than sham-operated control rats.
2. Concomitant treatment with metoprolol tartrate (2.5 mg/kg, intraperitoneally, twice daily) prevented the elevation in blood pressure induced by adrenaline from osmotic minipumps. Such metoprolol treatment did not affect the blood pressure of control rats.
3. Noradrenaline administered intraperitoneally from osmotic minipumps at the rate of 2.9 nmol/h had no significant effect on blood pressure over a 6-day period of observation.
4. Tachyphylaxis developed to the acute pressor responses to intermittent intravenous infusions of adrenaline in doses of 0.78 μg (4.24 nmol) every 10 min, but after 14 days of such treatment systolic and diastolic blood pressures were significantly greater than in control rats.
5. It is suggested that the increase in blood pressure produced by chronic treatment with adrenaline is due to the uptake and accumulation of adrenaline in noradrenergic nerve terminals, from which it is subsequently released as a cotransmitter that mediates a positive feedback loop on, transmission by acting on prejunctional β-adrenoceptors.
Plasma Concentrations of Catecholamines in Two Strains of Spontaneously Hypertensive Rats at Different Ages
Authors: Ferrari P. , Picotti G. B. , Minotti E. , Bondiolotti G. P. , Caravaggi A. M. , Bianchi G. 
Published: August 2015

1. Blood pressure was measured and plasma levels of noradrenaline and adrenaline were determined radioenzymatically under basal conditions and after 10% blood volume reduction in blood drawn through catheters previously implanted in young and adult rats of two different genetically hypertensive strains: the Kyoto strain (SHR) and the Milan strain (MHS), and in their respective controls: Wistar—Kyoto strain (WKY) and Milan normotensive strain (MNS).
2. Under basal conditions no differences were observed between plasma noradrenaline and adrenaline levels in SHR and MHS rats and in the controls, at any age. Haemorrhage produced a greater fall in the blood pressure (P &lt; 0.01) of young and adult hypertensive strains (SHR-MHS) than in WKY and MNS rats, and a greater rise in plasma adrenaline (P &lt; 0.01).
3. These results suggest that: (a) there may be differences in involvement of the sympathetic nervous system in the pathogenesis of hypertension in SHR and MHS rats but not such as to cause differences in plasma catecholamine levels in either young or adult rats; (b) haemorrhage activates the sympatho—adrenal systems more in SHR and MHS rats, than in controls, and the greater percentage fall in blood pressure is probably due to a difference in reflex venoconstriction.