bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for a Decreased Noradrenaline Sensitivity in Mesenteric Resistance Vessels from Rats with Chemical Renal Medullectomy
Authors: Bund S. J. , Heagerty A. M. , Fletcher A. , Swales J. D. 
Published: August 2015

1. Chemical renal medullectomy was performed in Wistar rats by intraperitoneal injection of 2-bromoethylamine hydrobromide (200 mg/kg body weight). The effect of this treatment upon blood pressure and mesenteric vascular reactivity and morphology was studied 3 weeks after treatment.
2. Blood pressure was significantly raised in medull-ectomized rats. The indirect systolic pressures (means ± sem) were 112 ± 2.4 mmHg (14.9 ± 0.32 kPa) and 123 ± 3.5 mmHg (16.4 ± 0.5 kPa) (P &lt; 0.02) for control (n = 12) and medullectomized (n = 12) rats, respectively. However, there were no significant changes in the morphology of the mesenteric resistance vessels.
3. Maximum pressor responses and Ca2+ sensitivities were unchanged in these vessels compared with controls, but the sensitivity to noradrenaline was significantly reduced. Noradrenaline pD2 (= −log ED50) values (means ± sem) were 5.87 ± 0.03 and 5.69 ± 0.08 (P &lt; 0.05) for control (n = 12) and medullectomized (n = 12) rats, respectively.
4. This study demonstrates that in this model of hypertension the noradrenaline sensitivity is reduced in mesenteric resistance vessels, but there are no detectable morphological changes associated with the rise in blood pressure.
Platelet Cytosolic Free Calcium in Essential Hypertension: Responses to Vasopressin
Authors: Dominiczak A. F. , Morton J. J. , Murray G. , Semple P. F. 
Published: August 2015

1. Resting and stimulated free calcium concentrations have been measured in platelets loaded with the fluorescent probe quin2 from 30 patients with essential hypertension and from 30 age-matched controls.
2. Cytosolic free calcium concentrations were 94.6 ± 2.7 (mean ± sem) in the hypertensive group and 91.7 ± 2.8 nmol/l in the normotensive group, the difference was not significant.
3. Arginine vasopressin caused a transient increase in platelet free calcium concentration in all subjects. In the presence of extracellular calcium the increase was significantly higher in the control subjects than in the hypertensive patients (P = 0.005). In the absence of extracellular calcium, arginine vasopressin caused much smaller increases, and there was then no difference between the responses of the two groups.
4. Platelet free calcium concentrations were measured again in 13 patients after 8 weeks treatment with either verapamil (n = 6) or atenolol (n = 7). The reductions in systolic pressure after drug treatment were correlated with the changes in cytosolic free calcium concentrations (r = 0.75, P &lt; 0.01).
Expression of the Caeruloplasmin Gene in the Adult and Neonatal Rat Liver
Authors: Barrow L. , Tanner M. S. , Critchley D. R. 
Published: August 2015

1. It has been suggested that low levels of serum caeruloplasmin in Wilson's disease result from the failure to switch from a fetal to an adult mode of caeruloplasmin gene expression. To investigate postnatal expression of the caeruloplasmin gene, steady-state levels of caeruloplasmin messenger RNA in adult and neonatal rat liver were measured.
2. Copper parameters observed in neonatal rats were similar to those seen in Wilson's disease: hepatic copper concentration was significantly elevated (neonatal 164 ± 35 μg/g, adults 50 ± 8 μg/g, P &lt; .001) and serum copper and caeruloplasmin levels were low (neonatal 0.5 ± 0.1 μg/ml, adults 1.3 ± 0.2 μg/ml, P &lt; .001; neonatal 0.20 ± 0.04 arbitrary units, adults 0.69 ± 0.16 arbitrary units, P &lt; .001), respectively.
3. Caeruloplasmin messenger RNA levels were analysed by Northern and dot blotting using a 12P-labelled caeruloplasmin complementary DNA probe. A caeruloplasmin messenger RNA of approximately 4.4 kilobases was detected in both adult and neonatal rat liver, with no significant difference observed in steady-state levels.
4. A step subsequent to caeruloplasmin gene transcription must therefore be impaired in neonatal rats.
Inhibitory Role of Ca2+ in the Control of Renin Secretion: A Study Using Supervised Dispersed Rat Renal Cortical Cells
Authors: Pardy Karen , Williams B. C. , Noble A. R. 
Published: August 2015

1. The role of Ca2+ in the control of renin release was investigated using a collagenase-dispersed rat kidney cortex cell preparation.
2. Superfusion with a series of low [Ca2+] buffers in either ascending or descending order of concentration increased renin release. Exposure to 0.06 mmol/l Ca2+ increased release by 120% (P &lt; 0.001) when presented as the first buffer in ascending order of concentration and by 79% (P &lt; 0.001) when presented as the fourth and last in a series of descending order.
3. The Ca2+ entry blocking drug diltiazem in a range of concentrations increased renin release and at 10−5 mol/l diltiazem the mean stimulation was 35% (P &lt; 0.01).
4. 8-(N,N-Diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8) reduces the release of Ca2+ from intracellular stores and, studied over a range of concentrations, this compound increased renin release. At 10−5 mol/l TMB-8 the mean increase was 44% (P &lt; 0.001).
5. None of these experimental manipulations, low [Ca2+], diltiazem or TMB-8, had any effect on the release of adenosine 3′:5′-cyclic monophosphate into the cell superfusate, indicating that a decrease in intracellular [Ca2+] increases renin release by a mechanism which is independent of changes in adenosine 3′:5′-cyclic monophosphate production.
6. Effects of low [Ca2+], diltiazem and TMB-8 on renin secretion were all shown to be reversible when superfusion with control buffer was resumed.
Atrial Natriuretic Factor: Comparability of Venous and Arterial Plasma Measurements in Man at Rest and during Exercise
Authors: Kanstrup I. L. , Høilund-Carlsen P. F. , Nielsen M. Damkjær , Marving J. , Gadsbøsll N. 
Published: August 2015

1. Simultaneously obtained arterial and venous plasma atrial natriuretic factor (ANF) concentrations were compared at supine rest and during graded dynamic leg exercise in 10 healthy male subjects (aged 33–51 years).
2. Arterial ANF concentrations ranged between 12 and 179 pg/ml and venous concentrations between 9 and 177 pg/ml.
3. A positive correlation between arterial and venous concentrations was found (r = 0.984).
4. Arterial ANF concentrations were higher than venous concentrations in all pairs of samples (n = 31), but the difference was small and changed little with exercise: the mean difference was 5 pg/ml at rest, 12 pg/ml during submaximal exercise and 6 pg/ml during maximal exercise.
5. The extraction ratios for ANF varied greatly, but were in general lower (P &lt; 0.05) during maximal exercise (median 0.07, range 0.01–0.32) than at rest (median 0.22, range 0.05–0.33).
6. It was concluded that the plasma ANF concentration in a peripheral arm vein is a good indicator of the systemic peptide concentration at rest as well as during dynamic leg exercise.
Erythrocyte Sodium/Lithium Countertransport and Renal Lithium Clearance in a Random Sample of Untreated Middle-Aged Men
Authors: Strazzullo Pasquale , Cappuccio Francesco P. , Trevisan Maurizio , Iacoviello Licia , Iacone Roberto , Jossa Fabrizio , Giorgione Nicola , Farinaro Eduardo , Mancini Mario 
Published: August 2015

1. It has been proposed that the enhanced erythrocyte Na+/Li+ countertransport observed in many patients with essential hypertension could be a marker of abnormal renal proximal tubular function. We thus investigated the relationship of blood pressure and Na+/Li+ countertransport to an index of proximal tubular function such as renal Li+ clearance.
2. The study was carried out in a sample of 299 untreated male subjects (aged 21–59 years) randomly selected from a population at work. Na+/Li+ counter-transport was measured in a representative sub-group of 176 men.
3. We did not detect statistically significant correlation of either blood pressure or Na+/Li+ countertransport (Vmax) with fractional excretion of Li+, while confirming the existence of a significant continuous association of blood pressure and body mass index with Na+/Li+ countertransport (P &lt; 0.01).
4. A sub-sample of 57 participants belonging to the lowest or the highest quintiles of Na+/Li+ counter-transport distribution repeated the Li+ clearance study after moderate Na+ restriction.
5. Although fractional excretions of Na+ and Li+ were reduced on the low Na+ diet (both P &lt; 0.001), they did not differ significantly between groups.
6. Our results are at variance with the findings of a recent case-control study in a young age group and suggest that further studies are necessary before a conclusion can be drawn as to the suitability of Na+/Li+ countertransport as a marker of Na+ reabsorption in the renal proximal tubule.
Muscle Enzyme Adaptation in Patients with Peripheral Arterial Insufficiency: Spontaneous Adaptation, Effect of Different Treatments and Consequences on Walking Performance
Authors: Lundgren Fredrik , Dahllöf A.-G. , Scherstén T. , Bylund-Fellenius A.-C. 
Published: August 2015

1. The activities of phosphofructokinase (PFK), citrate synthetase (CS), lactate dehydrogenase (LDH), 3-hydroxyacyl-CoA dehydrogenase (ACDH) and cytochrome-c oxidase (Cyt-ox) in the calf muscle tissue were compared in subjects with intermittent claudication (n = 38) and controls (n = 20). The activities of CS, ACDH and Cyt-ox were increased and the activity of Cyt-ox was positively correlated to the maximal walking distance (MWD) in the patients.
2. Thirty-three patients with intermittent claudication were randomized to three treatment groups: (1) operative surgery, (2) operative surgery supplemented with physical training and (3) physical training alone. Before and after 6–12 months of treatment, symptom-free walking distance (SFWD), MWD, ankle-brachial blood pressure quotient (ankle index), maximal plethysmographic calf blood flow (MPBF) and the activities of PFK, CS, LDH, ACDH and Cyt-ox were measured.
3. SFWD and MWD increased in all three groups. Ankle index and MPBF increased in groups 1 and 2, but were unchanged in group 3. The activities of Cyt-ox and CS decreased with operation, but the activity of Cyt-ox was further augmented with training in group 3. Overall, the change in ankle index explained 80–90% of the variability in walking performance. In a separate analysis, the increased activity of Cyt-ox in group 3 was positively correlated to, and explained 31% of the variability in, the improvement in SFWD.
4. These findings indicate that both physical activity and a reduced calf blood flow are necessary conditions for the enzymatic adaptation to take place. A causal relationship betweeen metabolic adaptation in the muscle tissue and walking performance is suggested. The possible importance of other factors as determinants of walking ability is also discussed.
Reduced Selenium Status of Patients with Asthma
Authors: Stone J. , Hinks L. J. , Beasley R. , Holgate S. T. , Clayton B. A. 
Published: August 2015

1. Selenium is an essential component of glutathione peroxidase (GSH-Px, EC 1.11.1.9), an enzyme which helps protect cells against damage caused by free radicals and hydroperoxides.
2. We report the plasma, whole blood and platelet concentrations of selenium, and whole blood and platelet activities of GSH-Px, in 49 patients with asthma, 23 of whom had coexisting eczema, and 76 healthy control subjects.
3. The asthmatic patients had significantly lower concentrations of selenium measured in plasma (P &lt; 0.01) and whole blood (P &lt; 0.001), but not in platelets. When the data were summarized as odds ratios there was a highly significant 3.54- and 5.08-fold increased probability of asthma observed for the lower range of plasma and whole blood selenium concentrations, respectively.
4. No overall decrease in platelet or whole blood GSH-Px activity was found when the asthmatic and control groups were compared.
5. Although patients with symptomatic asthma have a reduced selenium status, this does not appear to influence the antioxidant capacity of their circulating blood cells.
Sympathetic Vasoconstriction as a Mechanism of Action of Ouabain in Forearm Arterioles of Hypertensive Patients
Authors: Pedrinelli Roberto , Taddei Stefano , Salvetti Antonio 
Published: August 2015

1. The interaction of ouabain, a Na+/K+ adenosine 5′-triphosphatase inhibitor, with sympathetic mechanisms of vasoconstriction, as well as its possible site(s) of action, were investigated in forearm arterioles of patients with uncomplicated hypertension.
2. Intra-arterial infusion of ouabain per se decreased forearm blood flow without changes in systemic arterial pressure or contralateral flow. However, the vasoconstrictor effect of the glycoside was abolished after local pre-treatment with either phentolamine, a competitive α-adrenoceptor antagonist, or bretylium tosylate, a neurotransmitter blocker.
3. To exclude a non-specific effect due to the vasodilatation, a similar protocol was performed using histamine, which acts independently of sympathetic mechanisms. The vascular effect of ouabain was maintained in spite of histamine-induced increases in forearm blood flow even greater than those obtained from either blocker.
4. To discriminate between pre- and post-synaptic site(s) of action of ouabain, exogenous noradrenaline was infused intra-arterially after inactivation of local neurotransmitter release by bretylium, thus causing direct postsynaptic vascular α-adrenoceptor stimulation. Under these conditions, noradrenaline decreased forearm blood flow irrespective of the presence or absence of ouabain.
5. Thus, local sympatholysis by drugs acting on different levels of the sympathetic neuroeffector junction abolished the effect of ouabain, whereas histamine did not influence it. The data provide positive evidence for an effect of ouabain on sympathetically mediated vasoconstriction. This action is apparently not exerted at a postsynaptic site but possibly by enhancing neurotransmitter release.
6. If a circulating endogenous ouabain-like Na+/K+ adenosine 5′-triphosphatase inhibitor is relevant to the development of hypertension in man, it might act through a similar mechanism.
Stimulation of Erythrocyte and Renal Na+, K+-Adenosine Triphosphatase Activity by Antidigoxin Antibody in Normal Rats
Authors: Wagener Osvaldo E. , Mujais Salim K. , Del Greco Francesco , Quintanilla Antonio P. 
Published: August 2015

1. A circulating ouabain-like factor which inhibits the Na+, K+-pump has been implicated in volume-expanded states. To assess the role of this putative factor in normovolaemic rats, we measured erythrocyte and renal Na+, K+-adenosine triphosphatase activity after the infusion of a mixture of high-affinity digoxin-binding Fab fragments (Digibind) capable of removing digoxin from pump sites.
2. Compared with either saline (vehicle) or sheep immunoglobin G, infusion of the antidigoxin antibody caused a moderate increase of Na+, K+-adenosine triphosphatase activity in the erythrocyte (saline 348 ± 12; immunoglobulin G 339 ± 16; antidigoxin antibody 432 ± 22 nmol h−1 mg−1; P &lt; 0.005 by analysis of variance) and a larger increase in the renal cortex (saline 9.7 ± 0.9; immunoglobulin G 9 ± 1.4; antidigoxin antibody 24.3 ± 1.8 μmol h−1 mg−1; P &lt; 0.0005 by analysis of variance) without a change in blood pressure
3. These results are consistent with the presence of a digoxin-like inhibitor of the Na+, K+ -pump in normal rats.
A Widespread Abnormality of Renin Gene Expression in the Spontaneously Hypertensive Rat: Modulation in Some Tissues with the Development of Hypertension
Authors: Samani Nilesh J. , Swales John D. , Brammar William J. 
Published: August 2015

1. Renin messenger RNA (mRNA) levels were compared in the kidneys, livers, brains, adrenals, aortae and hearts of spontaneously hypertensive (SHR) and Wistar—Kyoto (WKY) rats at 5 and 12 weeks of age using a ribonuclease-protection technique
2. Relative levels of renin mRNA were increased in the kidney, liver, brain, adrenal and heart of the young SHR compared with the WKY. In the aorta, levels were similar in the two strains at 5 weeks
3. In 12-week-old animals, while increased levels persisted in the liver, brain and adrenal of the SHR, the level in the kidney was now the same in the two strains and the levels in the heart and aorta were lower in the SHR compared with the WKY
4. Renin mRNA levels in the kidneys of SHR and WKY were also compared by Northern blotting and confirmed the observations made with the ribonuclease-protection technique
5. The findings indicate a widespread abnormality of renin gene expression in the SHR which is modulated in some tissues by the development of hypertension
6. While the mechanism(s) for the abnormality remains to be determined, the increased renin mRNA levels in the SHR in several tissues concerned with blood pressure regulation suggests an important role for the renin-angiotensin system in the development and maintenance of hypertension
7. However, the finding of increased renin mRNA in the liver also suggests abnormalities in other, as yet unknown, functions of the renin—angiotensin system in the SHR.
Effect of α-Human Atrial Natriuretic Peptide on Proteinuria in Patients with Primary Glomerular Diseases
Authors: Ishii Masao , Hirata Yasunobu , Sugimoto Tokuichiro , Matsuoka Hiroaki , Kimura Kenjiro , Ishimitsu Toshihiko , Fukui Kazushige , Sugimoto Tsuneaki , Kurosawa Yuko , Kiyose Hiroshi , Kangawa Kenji , Matsuo Hisayuki 
Published: August 2015

1. The effects of synthetic α-human atrial natriuretic peptide (α-hANP) on urinary protein excretion were examined in nine healthy subjects and 20 patients with primary glomerular diseases who had proteinuria of 1.0 g or more per day. Synthetic α-hANP was intravenously infused into supine subjects at a rate of 8.3 pmol min−1 kg−1 for 40 min
2. Before α-hANP infusion, the plasma concentration of immunoreactive α-hANP was significantly higher in the patients with glomerulonephritis than in the normal subjects (44.3 ± 8.7 vs 19.4 ± 3.0 pmol/l, mean ± sem, P &lt; 0.01) and it showed a positive correlation with mean arterial pressure (rs = 0.84, P &lt; 0.001) and a negative correlation with creatinine clearance (rs = −0.50, P &lt; 0.01)
3. During infusion of α-hANP, although the urinary excretion of protein did not change significantly in the normal subjects, it increased from 0.6 ± 0.2 to 3.0 ± 0.8 mg min−1 m−2 (P &lt; 0.001) in the patients with glomerulonephritis. The urinary protein/creatinine ratio did not change significantly in the former (from 0.18 ± 0.05 to 0.22 ± 0.06; NS), whereas it rose from 3.25 ± 0.94 to 7.62 ± 1.31 (P &lt; 0.001) in the latter
4. The urinary excretions of albumin and of α1-, α2-, β- and γ-globulins, which were electrophoretically analysed, all increased in eight nephrotic patients during or immediately after infusion of α-hANP
5. The α-hANP infusion increased urinary volume, urinary excretion of sodium and creatinine clearance in the glomerulonephritic patients, whereas the changes in urinary volume and creatinine clearance were not significant in the normal subjects. Renal blood flow did not show any significant changes in either group. Packed cell volume increased slightly, but significantly, in the two groups, whereas plasma renin activity did not show any significant changes in either group
6. These results suggest that α-hANP increases the transglomerular permeability to plasma protein in damaged glomeruli, most likely affecting the steric hindrance.
Sodium Handling in the Isolated Perfused Kidney of the Cirrhotic Rat
Authors: Firth John D. , Gove Christopher , Panos Marios Z. , Raine Anthony E. G. , Williams Roger , Ledingham John G. G. 
Published: August 2015

1. In cirrhosis the kidney tends to retain salt and water abnormally. Two theories have been proposed to account for this: the ‘underfilling’ theory, in which sodium retention is thought to occur secondary to perceived underfilling of the circulation, and the ‘overflow’ theory, in which sodium retention is considered to be due to a primary renal defect
2. Using the model of cirrhosis produced by carbon tetrachloride administration in the rat, the ability of the kidney to excrete sodium has been examined in vivo and during isolated perfusion
3. Cirrhotic animals demonstrated a reduced ability to excrete an acute sodium load: 6 h after 2 mmol of sodium was given by gavage, 27.5 ± 10.5% had been excreted by the cirrhotic rats and 62.5 ± 7.0% by control rats (P &lt; 0.025)
4. In contrast, during isolated perfusion, kidneys from cirrhotic animals excreted the same amount of sodium as control animals over a range of perfusion pressures from 90 to 150 mmHg (12 to 20 kPa)
5. The data are consistent with the view that in cirrhosis the kidney retains sodium in response to immediate external factors.
A study of patients with alcoholic liver disease by 31P nuclear magnetic resonance spectroscopy
Authors: Angus Peter W. , Dixon Ruth M. , Rajagopalan Bheeshma , Ryley Nicholas G. , Simpson Kenneth J. , Peters Timothy J. , Jewell Derek P. , Radda George K. 
Published: August 2015

1. Patients with a history of alcohol abuse were studied by 31P n.m.r. spectroscopy of the liver in vivo, and the results were related to the pattern of disease assessed by standard biochemical and histological techniques.
2. The ratios of metabolites measured from the 31P n.m.r. spectra were abnormal in patients with alcoholic hepatatis but not in those with fatty change or cirrhosis in the absence of hepatitis. In particular, the levels of phosphomonoesters were raised, with respect either to Pi, or to adenosine 5′-triphosphate. The level of phosphomonoesters showed a significant positive correlation with the severity of alcoholic hepatitis, assessed by histology.
3. The ratio of Pi to adenosine 5′-triphosphate was used as a measure of the energy status of the hepatocytes, and was unchanged between patients and controls.
Age-independent forearm vasodilatation by acetylcholine and adenosine 5′-triphosphate in humans
Authors: Imaizumi Tsutomu , Takeshita Akira , Suzuki Satoshi , Yoshida Megumu , Ando Shinichi , Nakamura Motoomi 
Published: August 2015

1. Forearm vasodilator responses to acetylcholine, ATP and sodium nitroprusside were examined in healthy young (20 ± 1 years, n = 9), middle-aged (46 ± 2 years, n = 6) and old (57 ± 1 years, n = 6) subjects.
2. A brachial artery was cannulated with a 20-gauge cannula through which drugs at graded doses were locally infused for 2 min at each dose. During drug infusions, forearm blood flow was continuously measured at 15 s intervals using a plethysmograph. Forearm vascular resistance was calculated from forearm blood flow and mean blood pressure obtained in the opposite arm. Basal forearm blood flow and forearm vascular resistance did not differ between the three groups.
3. Acetylcholine and ATP were used to examine endothelium-dependent vasodilatation, and sodium nitroprusside was used to examine endothelium-independent vasodilatation. All three drugs caused dose-dependent increases in forearm blood flow (P &lt; 0.01) and decreases in forearm vascular resistance (P &lt; 0.01). The increases in forearm blood flow or decreases in forearm vascular resistance in response to infusions of the three drugs did not differ between the three groups.
4. These results suggest that endothelium-dependent and endothelium-independent vasodilatation in forearm resistance arteries do not alter with ageing in humans.