bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of a Low-Salt Diet and of Acute Salt Loading on Blood Pressure and Intralymphocytic Sodium Concentration in Young Subjects with Borderline Hypertension
Authors: Costa F. V. , Ambrosioni E. , Montebugnoli L. , Paccaloni L. , Vasconi L. , Magnani B. 
Published: August 2015

1. Three groups of young patients with borderline hypertension were studied for a 12 months period. The first was on a free sodium diet while the second was on a low-salt diet. The third group of patients underwent acute salt loading.
2. After 12 months the group on free diet showed a significant increase of intralymphocytic sodium but no change in blood pressure was noted. Five patients who were re-checked after 24 months also had a significant increase in blood pressure.
3. Patients treated with a low-salt diet showed a significant decrease of both intralymphocytic sodium concentration and blood pressure.
4. After acute salt loading, borderline subjects with high intralymphocytic sodium showed a significant greater natriuresis whereas intralymphocytic sodium increased only in those subjects in whom it was initially normal.
Effect of Sodium Intake on Angiotensin-Converting Enzyme Activity of Aorta in Rats
Authors: Mizuno Kenji , Hata Shunichi , Fukuchi Soitsu 
Published: August 2015

1. The effect of sodium intake on angiotensin-converting enzyme activity in subcellular fractions of aorta (homogenate, mitochondria, microsomes and supernatant) was studied in normotensive and spontaneously hypertensive rats.
2. Angiotensin-converting enzyme activity was extremely high in the supernatant fraction in normotensive and spontaneously hypertensive rats.
3. Total converting enzyme activity in spontaneously hypertensive rats was 34% higher than that in normotensive rats.
4. Increased sodium intake resulted in a marked reduction, almost to zero, of converting enzyme activity in each fraction of aorta in normotensive and spontaneously hypertensive rats.
5. Converting enzyme, widely distributed in subcellular fractions of the aorta, may play a possible rôle in the local control of vascular tone. It is likely that sodium intake inhibits production of the enzyme in vascular tissue.
Captopril Attenuates Adrenergic Vasoconstriction in Rat Mesenteric Arteries by Angiotensin-Dependent and -Independent Mechanisms
Authors: Collis M. G. , Keddie J. R. 
Published: August 2015

1. Angiotensin-converting enzyme inhibitors can attenuate reflex sympathetic vasoconstriction in vivo. We have investigated the effects of captopril (SQ 14 225) on adrenergic vasoconstrictor mechanisms in isolated, Krebs-Ringer solution perfused, rat mesenteric arteries.
2. Low concentrations of captopril (2 × 10−6 mol/l) did not alter the vasoconstrictor response evoked by sympathetic nerve stimulation.
3. Exogenous angiotensin I and II did not have a direct vasoconstrictor effect, but caused dose-related increases in the amplitude of responses induced by nerve stimulation.
4. The potentiating effect of angiotensin I was antagonized by captopril (6.7 × 10−8–2 × 10−6 mol/l) and by saralasin (10−8 mol/l). The potentiating effect of angiotensin II was antagonized by saralasin only.
5. In the absence of exogenous peptides high concentrations of captopril (1 × 10−4–3 × 10−4 mol/l) antagonized vasoconstrictor responses evoked by sympathetic nerve stimulation and exogenous noradrenaline, but not those evoked by potassium chloride.
6. These results indicate that captopril can have two types of inhibitory effect at the adrenergic neuro-effector junction. High concentrations antagonize responses to noradrenaline and nerve stimulation. This effect is independent of peptide hormones and is unlikely to occur in vivo. Lower concentrations block the local vascular conversion of angiotensin I into II.
As angiotensin II is an important peripheral amplifier of adrenergic vasoconstriction, this effect will also reduce sympathetic vasoconstrictor tone. This latter interaction could explain the inhibitory effect of converting enzyme inhibitors on sympathetic reflexes.
Increased Sodium Content and Altered Sodium Transport in Thymocytes of Spontaneously Hypertensive Rats
Authors: Jones R. B. , Patrick J. , Hilton P. J. 
Published: August 2015

1. The intracellular sodium content and the sodium efflux rate constant have been determined in vitro in thymocytes derived from the Okamato-Aoki strain of spontaneously hypertensive rats.
2. A strong positive correlation between the systolic blood pressure and the sodium content of thymocytes was observed (r = 0.59, n = 39, P &lt; 0.001).
3. The rate constant for total sodium efflux was negatively correlated with systolic blood pressure (r = −0.43, n = 45, P &lt; 0.005) and this was due to a fall in the ouabain-sensitive component of sodium efflux.
4. Sodium efflux, influx and the thymocyte potassium content were not related to the blood pressure.
Relationship between Altered Na+–K+ Cotransport and Na+–Li+ Countertransport in the Erythrocytes of ‘essential’ Hypertensive Patients
Authors: Cusi D. , Barlassina C. , Ferrandi M. , Palazzi P. , Celega E. , Bianchi G. 
Published: August 2015

1. The maximal rate of activity of sodium extrusion by the sodium pump, Na+—K+ outward cotransport, passive permeability to sodium and potassium, Na+—Li+ countertransport, and passive permeability to lithium were measured in 45 essential hypertensive patients, 24 young normotensive subjects with at least one hypertensive parent and 24 normotensive subjects with both parents normotensive.
2. The maximal rate of activity of the sodium pump and the rate constants for passive permeability to sodium, potassium and lithium were similar in the three groups.
3. The mean value for Na+—K+ outward cotransport was significantly lower and that for Na+—Li+ countertransport significantly higher in the hypertensive patients than in the normotensive subjects without a family history of hypertension, but there was a great overlap between individual values. The offspring of hypertensive parents had intermediate values.
4. A highly significant positive correlation existed between Na+—K+ cotransport and Na+—Li+ countertransport both in the normotensive and in the hypertensive subjects, indicating that in the latter there were some with high Na+—Li+ countertransport and others with low Na+—K+ cotransport.
5. In nine hypertensive families studied, if an alteration of the transport system was detected in a hypertensive propositus, the same type of alteration was also found in his still normotensive offspring, thus indicating a familial tendency for the alteration to occur.
Effect of Acute and Chronic Salt Loading on Erythrocyte 22Na Efflux in Males with Essential Hypertension
Authors: Myers J. B. , Fitzgibbon W. R. , Morgan T. O. 
Published: August 2015

1. Present results confirm our previous work which showed that a sodium intake over 3 mmol day−1 kg−1 decreased the total erythrocyte efflux rate constant in untreated males with essential hypertension.
2. The infusion of saline (2.25 mmol of Na+/kg) over 30 min decreased the efflux rate constant.
3. The change after chronic sodium loading and the intravenous infusion of saline is in the ouabain-sensitive component (ouabain-sensitive Na+, K+ ATPase pump activity) of total efflux.
4. The reduction in efflux by an acute sodium load occurred only when chronic sodium intake was low.
5. Posture did not affect the efflux rate constant whether sodium intake was high or low.
6. The reduction in efflux after chronic ingestion and acute administration of sodium occurred only when erythrocytes were incubated in plasma. It did not occur in artificial medium, which suggested that a plasma factor mediated the effect of added sodium on cell sodium efflux.
7. The effect of sodium on cell sodium transport by a plasma factor with ouabain-like properties (which may be a natriuretic hormone) constitutes a regulatory system. This system, the sodium-ouabain-vsensitive cell sodium-transport pathway system, has important implications for the understanding of blood pressure control and sodium homeostasis.
Intracellular Cation Activities and Concentrations in Spontaneously Hypertensive and Normotensive Rats
Authors: Zidek W. , Vetter H. , Zumkley H. , Losse H. 
Published: August 2015

1. The intracellular concentrations of Na+, K+ and Ca2+ were measured in the erythrocytes of spontaneously hypertensive rats and normotensive Wistar rats.
2. The intracellular Na+ concentration in hypertensive rats was slightly elevated at 3.16 ± 0.25 compared with 2.85 ± 0.35 mmol/l (P ≈ 0.05) and intracellular Na+ activity was markedly increased in hypertensive rats.
3. Intracellular Ca2+ activity was 7519 ± 28 990 nmol/l of free water in hypertensive rats compared with 123 ± 98 in controls (P &lt; 0.01).
4. The cytoplasm of hypertensive animals did not buffer Ca2+ as effectively as that of normal animals.
5. It is concluded that a decreased binding capacity of intracellular macromolecules for Na+ and Ca2+ may explain the disturbances of intracellular electrolyte composition in spontaneously hypertensive rats.
Carotid Sinus Reflex Control of Renin Release in Hypertensive Subjects with High Renin Secretion
Authors: Mancia G. , Ferrari A. , Leonetti G. , Gregorini Luisa , Terzoli Laura , Parati G. , Bianchini C. , Zanchetti A. 
Published: August 2015

1. Carotid baroreceptor manipulation (neckchamber technique) and passive head-up tilting were used in ten patients with renovascular hypertension and in five subjects with essential hypertension under diuretic treatment to study reflex control of renin secretion” at high basal-renin production rates.
2. Reflex effects of carotid baroreceptor manipulation on renin secretion were only minor. During baroreceptor deactivation there was a moderate increase in mean arterial pressure, but an inconsistent change in the renal venous—arterial difference in plasma renin activity (PRA).
3. During baroreceptor stimulation there was a modest fall in mean arterial pressure and a marked rise in the renal venous—arterial difference in PRA. This was opposite to the fall which might have been predicted as a result of the sympathetic depressor influence of the baroreceptor stimulus. Conversely, tilting increased the venous—arterial PRA difference by about 200%.
4. It is concluded that when renin production rate is high carotid baroreceptors exert little control over renin release, just as when renin production is low. Reflex control of renin, however, is very active in subjects with a high renin production, probably due to receptors in the cardiopulmonary region.
Plasma Angiotensin II Concentration Regulates Vascular but Not Adrenal Responsiveness to Restriction of Sodium Intake in Normal Man
Authors: Dawson-Hughes Bess F. , Moore T. J. , Dluhy R. G. , Hollenberg N. K. , Williams G. H. 
Published: August 2015

1. Sodium restriction increases adrenal and decreases vascular sensitivity to angiotensin II (ANG II). These responses may be mediated either by the circulating level of ANG II or other mechanisms also modified by a change in sodium balance. To assess the importance of the ANG II level, captopril, an oral converting enzyme inhibitor, was used to lower the plasma ANG II level to the sodium-loaded range while maintaining subjects in low sodium balance.
2. Normal volunteer subjects received an infusion of ANG II in increasing doses in three states: high sodium intake, low sodium intake and low sodium intake after pretreatment with captopril.
3. Basal levels of ANG II on high-sodium diet and low-sodium diet plus captopril were similar. In the ANG II infusion studies the slope of the aldosterone—ANG II regression line on low sodium intake was significantly steeper than that on high sodium intake. After the addition of captopril the slope was not decreased, indicating that the endogenous ANG II concentration is not necessary to maintain adrenal sensitivity during sodium restriction.
4. In the ANG II infusion studies the slope of the mean blood pressure—ANG II regression line on high sodium intake was significantly steeper than that on low sodium intake. The addition of captopril to sodium-restricted subjects caused the slope of the regression relationship to increase significantly, consistent with an enhanced vascular responsiveness when endogenous ANG II levels were lowered. However, the slope on low sodium plus captopril did not increase to the level of subjects on a high-sodium diet, suggesting that factors in addition to the circulating ANG II level are also important in regulating the vascular responsiveness to ANG II.
Calcium Efflux and Steroid Output from Superfused Rat Adrenal Cells: Effects of Potassium, Adrenocorticotropic Hormone, 5-Hydroxytryptamine, Adenosine 3′:5′-Cyclic Monophosphate and Angiotensins II and III
Authors: Williams B. C. , McDougall J. G. , Tait J. F. , Tait S. A. S. 
Published: August 2015

1. The efflux of 45Ca from prelabelled dispersed rat adrenal capsular and decapsulated cell preparations was studied with a column superfusion system. Corticosterone and aldosterone outputs were measured by direct and extraction radioimmunoassays.
2. The stimulants potassium, adrenocorticotropic hormone (ACTH), serotonin and adenosine 3′:5′-cyclic monophosphate (cyclic AMP), at concentrations which gave marked increases in steroid output, had no significant effect on the rate of 45Ca efflux from capsular cell preparations (mainly zona glomerulosa).
3. ACTH, at a concentration which stimulated steriodogenesis similarly, did not alter the rate of 45Ca efflux from decapsulated cell preparations (zona fasciculata/reticularis).
4. [Asp1, Val5]Angiotensin II caused dose-dependent increases in the rate of 45Ca efflux from capsular cells which correlated with corresponding increases in steroid output, but had no effect either on 45Ca efflux or corticosterone output in decapsulated cell preparations. [desAsp1,Ile5]Angiotensin II (angiotensin III) caused similar dose-dependent increases in 45Ca efflux from capsular cells, which correlated with its effects on steroidogenesis, but was less potent in both respects than angiotensin II.
5. Lowered extracellular calcium caused a very marked and rapid increase in 45Ca efflux in capsular-cell preparations, which was not significantly modified by raising the extracellular potassium concentration, although stimulation of steriodogenesis was observed.
6. These findings suggest that in zona glomerulosa cells the stimulants potassium, ACTH, serotonin and cyclic AMP are not coupled to changes in calcium transport indicated by alterations in calcium efflux, whereas angiotensins II and III, the only stimulants examined which do not increase cyclic AMP in these cell preparations, appear to act through a calcium-mediated control mechanism. In zona fasciculata/reticularis cell preparations ACTH does not appear to be coupled to such changes in calcium transport.
Reduced Airway Vagal Tone in Diabetic Patients with Autonomic Neuropathy
Authors: Douglas N. J. , Campbell I. W. , Ewing D. J. , Clarke B. F. , Flenley D. C. 
Published: August 2015

1. Forced expiratory flow rates and specific airways conductance were measured before and after the inhalation of the atropine-like drug ipratropium bromide in 11 diabetic patients with autonomic neuropathy and a control group of 11 diabetic patients without autonomic neuropathy. Respiratory muscle function was assessed by recording maximal inspiratory and expiratory mouth pressures.
2. There was no difference between the two groups of diabetic patients in airway calibre before ipratropium bromide or in maximal mouth pressures.
3. Bronchodilatation after ipratropium bromide was greater in the control group than in the autonomic neuropathy group of patients.
4. It is concluded that, despite the lack of clinical evidence of respiratory involvement, patients with diabetic autonomic neuropathy have reduced airway vagal tone.
On the Extravascular Pool of Low-Density Lipoprotein in Rat Liver
Authors: Sigurdsson G. , Shames D. M. , Havel R. J. 
Published: August 2015

1. The mass of the extravascular pool of low-density lipoprotein (LDL) in liver was measured in rats injected intravenously with radioiodinated LDL by determining the radioactive iodine remaining in the extravascular tissues of liver and in plasma when the hepatic intravascular and extravascular radioactive iodine had equilibrated (equilibrium-time method).
2. The mass of the extravascular pool of LDL in the liver was about 6% of the total intravascular pool. Total extravascular pool of LDL in eight rats, obtained by multicompartmental analysis of the time-curve of disappearance of radioiodinated LDL from blood plasma, was 43 ± 15% (mean ± sd) of the intravascular pool.
3. Hence the hepatic extravascular pool comprises only about 14% of the total extravascular pool of LDL in the rat.
Associations between Sex Hormones, Thyroid Hormones and Lipoproteins
Authors: Heller R. F. , Miller N. E. , Lewis B. , Vermeulen A. , Fairney Angela , James V. H. T. , Swan A. V. 
Published: August 2015

1. A study of 150 middle-aged male industrial employees has shown significant positive correlations between plasma levels of high-density-lipoprotein (HDL) cholesterol and both serum testosterone and alcohol intake, and significant negative correlations between HDL cholesterol and both serum thyroxine and obesity. These associations persist when examined by multiple linear regression, indicating their independence.
2. Significant positive correlations are also shown between plasma triglyceride levels and both obesity and serum thyrotropic hormone (TSH) levels.
3. There are no evident relationships between serum oestrone or oestradiol and either HDL cholesterol or triglyceride levels, nor between any of the hormones and either total or low-density-lipoprotein (LDL) cholesterol.
4. Because of the potential importance in relation to coronary heart disease prevention, further studies are needed to try and understand the mechanisms of the associations between HDL cholesterol and obesity, alcohol intake and thyroid and sex hormone levels.
Production of Collagenase and Inhibitor (Timp) by Normal, Rheumatoid and Osteoarthritic Synovium In Vitro: Effects of Hydrocortisone and Indomethacin
Authors: McGuire Mary B. , Murphy Gillian , Reynolds J. J. , Russell R. G. G. 
Published: August 2015

1. the amounts of latent and active collagenase and of collagenase inhibitor (TIMP) produced by two normal, three rheumatoid and two osteoarthritic synovial specimens in culture were compared. Normal synovia produced TIMP, but little latent enzyme. Rheumatoid synovia produced higher levels of total collagenase activity than normal, of which up to 50% in one sample was present in the medium in an active form, whereas no specific inhibitory activity due to TIMP was detectable. the amounts of collagenase and TIMP produced by osteoarthritic synovia were more variable and appeared to reflect the degree of inflammation in the tissue at the time of initiating the cultures.
2. Concentrations of TIMP were usually higher in the culture media of normal, rheumatoid and osteoarthritic synovia when hydrocortisone was present. Correspondingly, amounts of total collagenase were reduced. Production of prostaglandin E (PGE) were inhibited in a dose-dependent manner by hydrocortisone.
3. Indomethacin had no consistent effect on the production of TIMP by rheumatoid and osteoarthritic synovia, although it tended to depress production of collagenase. the production of TIMP by normal synovia was depressed by indomethacin. No PGE was detectable in the media when indomethacin was present.
4. These results are consistent with those from previous animal studies, and we conclude that the balance between production of collagenase and TIMP may be critical in determining the extent of the destructive processes in arthritis. the ability of hydrocortisone to suppress production of collagenase and to increase free TIMP concentration, as well as to inhibit synthesis of prostaglandin, may explain in part how the drug exerts its therapeutic effects in patients with rheumatoid arthritis.
Characterization of Collagenase, other Metallo-Proteinases and An Inhibitor (Timp) Produced by Human Synovium and Cartilage in Culture
Authors: Murphy Gillian , McGuire Mary B. , Russell R. G. G. , Reynolds J. J. 
Published: August 2015

1. Explants of human synovium from normal, rheumatoid and osteoarthritic subjects produced proteinases in culture that could degrade connective tissue macromolecules at neutral pH.
2. the proteinases detected in the media were predominantly of the class requiring metal ions for activity, and occurred in either partially or wholly latent forms. Activation could be achieved by treatment with either trypsin or the organomercurial, 4-aminophenylmercuric acetate.
3. Explants of both normal and osteoarthritic synovium produced an inhibitor of collagenase in the early days of culture, similar to that previously described for rabbit tissues. in contrast, no free inhibitor could be detected in the media of rheumatoid synovial cultures.
4. Explants of normal human articular cartilage produced latent collagenase and free inhibitor in culture.
5. These findings suggest that the activity of tissue-derived metallo-proteinases may be controlled by locally synthesized inhibitors, by mechanisms analogous to those already described for rabbit model systems. Changes in the synthesis and degradation of inhibitor could be important in human diseases in which destruction of connective tissue is a prominent feature.
Effect of Dihydroxylated Metabolites of Vitamin D3 on Calcium Absorption in Uraemic Man
Authors: Muirhead N. , Catto G. R. D. , Gvozdanovic S. , Gvozdanovic D. , Edward N. 
Published: August 2015

1. Peak 47Ca absorption and 7 day 47Ca retention were measured by a whole-body radioactivity counting technique in 10 haemodialysis patients before and after treatment with 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] and 24,25-dihydroxycholecalciferol [24,25-(OH)2D3].
2. Before treatment all patients had low peak 47Ca absorption and 7 day 47Ca retention.
3. After treatment with 1,25-(OH)2D3 (0.25-1 μg/day for 4–12 months) peak 47Ca absorption and 7 day 47Ca retention returned to normal.
4. After treatment with 24,25-(OH)2D3 (2 μg/day for 4–12 months) peak 47Ca absorption and 7 day 47Ca retention remained at pre-treatment levels.
5. It is concluded that physiological doses of 24,25-(OH)2D3 have no effect on calcium absorption or retention in uraemic man.
Effect of Renal Failure on Erythrocyte Purine Nucleotide, Nucleoside and Base Concentrations and Some Related Enzyme Activities
Authors: Mansell M. A. , Allsop J. , North M. E. , Simmonds R. J. , Harkness R. A. , Watts R. W. E. 
Published: August 2015

1. We have studied purine metabolism in renal failure using high-pressure liquid chromatography to determine metabolite concentrations in erythrocytes and plasma, and microradiochemical assays of enzyme activity in erythrocytes.
2. the mean activities of some of the enzymes involved in purine metabolism were raised in renal failure. Significant elevations of adenylate kinase (EC 2.7.4.3), purine nucleoside phosphorylase (EC 2.4.2.1), hypoxanthine phosphoribosyltransferase (EC 2.4.2.8) and adenosine deaminase (EC 3.5.4.4) but not of adenine phosphoribosyltransferase (EC 2.4.2.7) and ribosephosphate pyrophosphokinase (phosphoribosylpyrophosphate synthetase; EC 2.7.6.1) activities were demonstrated. However, there was an overlap between results from patients with renal failure and normal (control) subjects. Erythrocyte phosphoribosylpyrophosphate levels were also unchanged.
3. Erythrocyte nucleotide concentrations especially those of inosine were raised in renal failure.
4. the plasma inosine was reduced in renal failure.
5. the significance of these changes is discussed.