bluuebunny/crossref_metadata_2025_split huggingface dataset:
Partial Characterization of Aortic Renin in the Spontaneously Hypertensive Rat and its Interrelationship with Plasma Renin, Blood Pressure and Sodium Balance
Authors: Barrett J. D. , Eggena P. , Sambhi M. P. 
Published: August 2015

1. A renin-like enzyme in aortic tissue of the spontaneously hypertensive rat was found to be a freely dissociable enzyme (saline homogenization) with an affinity for the renin inhibitor pepstatin. At neutral pH values, the enzyme was active in homologous plasma to produce angiotensin I, and therefore distinct from pseudorenin and cathepsin D. The arterial enzyme and semi-purified renal renin could not be distinguished on the basis of Km values by using homologous renin substrate
2. An inverse relationship between the aortic renin content of the spontaneously hypertensive rat and the progressive increase of systolic blood pressure was observed with age. In contrast to this strain of rat, aortic renin of the normotensive WKY strain did not decline with age.
3. Plasma renin concentration and the aortic renin content of the spontaneously hypertensive rat showed divergent changes in response to a blood pressure fall associated with acute diuretic therapy, chronic administration of hydrallazine and in some animals in response to chronic administration of propranolol.
4. A low sodium diet elevated both plasma and aortic renin and retarded the progressive increase of blood pressure in the spontaneously hypertensive rat. A high sodium diet accelerated the progress of hypertension with no effect on aortic or plasma renin.
5. Antihypertensive therapy (1–6 weeks), resulting in a lowering of conscious systolic blood pressure of the spontaneously hypertensive rat, consistently led to a decrease in aortic renin content.
The Tubular Reabsorption of Phosphate in Sickle-Cell Nephropathy
Authors: De Jong P. E. , Den Berg L. T. W. De Jong-Van , Van Eps L. W. Statius 
Published: August 2015

1. In a series of patients with sickle-cell anaemia, serum phosphate and magnesium concentrations were elevated. Serum calcium concentrations were normal. Urinary excretion of calcium was decreased.
2. The maximum tubular reabsorption of phosphate per litre of glomerular filtrate (TmP/GFR) was significantly increased in these patients.
3. The increase in phosphate reabsorption explains the elevated serum phosphate observed in these patients.
Nervous System and Hypertension
Authors: Chalmers J. P. 
Published: August 2015

1. Presynaptic regulation. The regulation of noradrenaline release by a wide variety of substances acting on presynaptic receptors suggests that local factors may play a greater role in the control of blood pressure than was previously believed and that a number of new approaches to the drug treatment of hypertension could be developed. It also raises the possibility that there might be differences in the presynaptic receptor populations of hypertensive and normotensive subjects or animals.
2. Central nerve pathways. There is a need for more precise delineation of central nerve tracts subserving a cardiovascular function and for greater use of morphological techniques to confirm the reliability of biochemical and physiological experiments in the central nervous system. Two appropriate techniques are described.
3. Models of experimental hypertension. (a) Neurogenic hypertension: interference with baroreceptor afferents can cause a permanent elevation of arterial pressure mediated by increased activity of peripheral sympathetic nerves and of descending noradrenergic nerves terminating in the spinal cord. Catecholamine nerve connections of the nucleus tractus solitarius serve mainly to modulate rather than to mediate baroreceptor reflexes. (b) DOCA—salt hypertension: increased peripheral sympathetic activity is important in both the initiation and the maintenance of this form of hypertension. The decrease in brain-stem noradrenaline turnover found in this model could play a determinant role in the development of the high blood pressure. (c) Renal hypertension: both central and peripheral nervous mechanisms contribute to the development and the early phase of ‘one-kidney’ hypertension in animals. Their role in the maintenance of this form of hypertension is still controversial. (d) Spontaneously hypertensive rats: peripheral and central mechanisms do not appear to have a major role in the maintenance of this form of hypertension. However, it seems possible that centrally evoked increases in peripheral sympathetic activity could be important in the initiation of the high blood pressure. (e) Central catecholamines and blood pressure control; central catecholaminergic nerves do not make up a single homogeneous system. For example, the activity of descending noradrenergic nerves in the spinal cord contributes to an elevation of arterial pressure, whereas the activity of catecholaminergic nerves in the dorsomedial medulla appears to have a depressor effect.
4. Human essential hypertension. (a) There is no good evidence that the nervous system plays the major primary role in the development or maintenance of essential human hypertension. (b) Effective treatment of raised blood pressure through nervous mechanisms requires an understanding of the factors that normally control the pressure and does not necessarily depend on reversing specific nervous processes responsible for producing the increase in pressure.
Albumin/Globulin Ratios, Colloid Osmotic Pressures and Lowry Protein Microanalysis in Rat Plasma
Authors: Weller D. , Azar S. , Johnson M. A. , Azar M. 
Published: August 2015

1. We have correlated measurements of colloid osmotic pressure with protein concentrations and albumin/globulin ratios. Plasma from normal rats of different genetic strains was used.
2. The Landis and Pappenheimer equation does not accurately predict colloid osmotic pressure properties of the normal rat plasma used, which had an albumin/globulin ratio of 0.74. Over the range 2.2−12.2 g of protein/100 ml, the measured colloid osmotic pressures vary between −5% and +10% from the value predicted by the equation.
3. In Wistar-derived genetically hypertensive and normotensive rats, albumin/globulin ratios were higher than those in common Wistar rats. Owing to the presence of higher globulins, plasma proteins were higher in Wistar than spontaneously hypertensive and normotensive rats, and colloid osmotic pressure was identical in the three groups.
4. When common Sprague—Dawley rats were obtained from two different suppliers, their albumin/globulin ratios were found to be different.
5. As the difference in albumin/globulin ratio between human and rat plasma becomes more pronounced, predicting rat plasma colloid osmotic pressure from the Landis and Pappenheimer equation becomes less accurate. Environmental and/or genetic factors play a role in the albumin/globulin ratio found in normal healthy rats.
6. Therefore albumin/globulin ratios should be measured in each experimental situation. If the ratios are close to that of human plasma, the Landis and Pappenheimer equation can be used. If not, a new colloid osmotic pressure-protein expression should be derived.
7. Calculation of glomerular capillary pressures from directly measured colloid osmotic pressure values reduces error.
Acute Effects of Diuretics on Potassium Exchange, Mechanical Function and the Action Potential in Rabbit Myocardium
Authors: Poole-Wilson P. A. , Cobbe S. M. , Fry C. H. 
Published: August 2015

1. We have studied the acute effects of frusemide, triamterene and amiloride on potassium exchange, the action potential and mechanical function of isolated rabbit myocardium.
2. Potassium exchange in the myocardium was unaltered by these diuretics.
3. Frusemide and amiloride did not affect the action potential of rabbit papillary muscles. Triamterene caused a transient shortening of the action potential.
4. Frusemide and triamterene did not alter myocardial mechanical function in rabbit papillary muscles or the interventricular septum. Amiloride caused a reduction of about 5% in developed tension in two out of three papillary muscles.
Plasma Noradrenaline and the Pressor Action of Exogenous Noradrenaline in Normotensive Subjects and Patients with Essential Hypertension
Authors: Philipp T. , Distler A. , Cordes U. , Wolff H. P. 
Published: August 2015

1. An inverse relationship was found between plasma noradrenaline and reactivity to exogenous noradrenaline in normotensive subjects.
2. The relationship between plasma noradrenaline and reactivity was disturbed in age-matched patients with essential hypertension.
3. A multiple-regression analysis showed a highly significant correlation between adrenergic activity and reactivity to noradrenaline and the mean arterial blood pressure level (r = 0·91). The results suggest that adrenergic activity and pressor response to noradrenaline combined are important determinants of arterial blood pressure.
4. An inverse relationship could also be demonstrated between plasma renin activity and reactivity to exogenous angiotensin II. No difference was observed between normotensive and hypertensive subjects.
Plasma Noradrenaline, Age and Blood Pressure: A Population Study
Authors: Jones D. H. , Hamilton C. A. , Reid J. L. 
Published: August 2015

1. Mean supine plasma noradrenaline was lower in 12 male laboratory staff (0·24 ± 0·02 μg/l) than similarly normotensive out-patients (0·44 ± 0·07 μg/l).
2. In 164 non-medical hospital staff, plasma noradrenaline increased with age in white males only.
3. Plasma noradrenaline was significantly higher in women than men.
4. There was no relationship between supine blood pressure and plasma noradrenaline in normotensive or hypertensive subjects.
Different Secretion Patterns of Active and Inactive Renin in Man
Authors: Kappelgaard A. M. , Giese J. , Ibsen H. , Nielsen M. Damkjær , Rabøl A. 
Published: August 2015

1. In plasma samples from normal subjects and patients with untreated essential hypertension, the concentration of inactive renin (as measured after acidification) was on average 4–5 times higher than the concentration of active renin (as measured without acidification).
2. Plasma angiotensin II concentration was correlated to active renin but not to inactive renin.
3. A hyperacute stimulation induced by infusion of saralasin resulted in a marked rise of active renin, whereas inactive renin remained unchanged.
4. An acute stimulation induced by frusemide and ambulation led to a considerable rise in active renin and a slight, but significant, rise of inactive renin.
5. Stimulation with oral thiazide over 5 days induced a seven-fold rise of active renin, with a doubling of inactive renin. Thiazide treatment for 3 months led to a four-fold rise of active renin and a three-fold rise of inactive renin.
6. There was no difference between the concentrations of inactive renin in systemic plasma, ipsilateral and contralateral renal venous plasma in 12 patients with renovascular hypertension, neither before nor after infusion of saralasin with the associated fall in blood pressure.
7. We conclude that the time constants pertinent to secretion or release of active and inactive renin in man are of different orders of magnitude.
Alterations of Adrenal and Uterine Angiotensin II Receptors during Variation of Sodium Intake and/or Experimental Hypertension
Authors: Devynck M. A. , Pernollet M. G. , MacDonald G. J. , Matthews P. G. , Raisman R. S. , Meyer P. 
Published: August 2015

1. Angiotensin II receptors from rat adrenal gland and myometrium were studied during variation of sodium intake.
2. In both target-tissues low Na+ diet increased the number of receptors whereas a high Na+ diet did not modify the adrenocortical receptors but increased the number of uterine receptors.
3. Deoxycorticosterone and one kidney Goldblatt hypertension were associated with a decrease in the number of adrenal receptors.
4. Alterations of angiotensin II receptors alone cannot explain satisfactorily the variations of sensitivity of target-cells to angiotensin II during sodium balance changes.
Renal Prostaglandin Production in the Japanese (Kyoto) Spontaneously Hypertensive Rat
Authors: Dunn Michael J. 
Published: August 2015

1. Renal venous and urinary prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2α) were measured in spontaneously hypertensive (SH) rats and Wistar-Kyoto normotensive rats (WKy) of 4 different ages, ranging from 4 to 54 weeks.
2. Renal venous (plasma) PGE2 and PGF2α were similar in WKy and SH rats at all ages, except for greater PGF2α in 40–54 week old SH rats.
3. Urinary (24 h) PGE2 and PGF2α were similar in WKy and SH rats at all ages, except for greater PGE2 in 7–12 week old SH rats.
4. There was a significant trend for renal venous and urinary PGE2 and PGF2α to decrease with advancing age.
5. These experiments did not show evidence that the SH rat kidney, in vivo, has an abnormality of PGE2 or PGF2α production or degradation, which alters secretion or excretion of either prostaglandin.
Effects of Indomethacin Alone and during Diuretic or β-Adrenoreceptor-Blockade Therapy on Blood Pressure and the Renin System in Essential Hypertension
Authors: Lopez-Ovejero J. A. , Weber M. A. , Drayer J. I. M. , Sealey J. E. , Laragh J. H. 
Published: August 2015

1. Indomethacin was administered alone or in addition to either diuretic or propranolol therapy to three groups of patients with essential hypertension on a free sodium diet.
2. Indomethacin administration reduced renin secretion by about 30% in untreated uncomplicated hypertensive patients and by about 75% in those whose renin secretion had either been stimulated or suppressed by maintained diuretic or β-adrenoreceptor-blockade therapy.
3. Indomethacin administration produced no net effect on blood pressure in untreated patients with uncomplicated hypertension but it blunted or reversed the antihypertensive effect of either diuretic or propranolol therapy.
4. Salt and water retention may be an important factor in the blood pressure-raising effect of indomethacin during diuretic or propranolol therapy: In addition, prostaglandin synthesis may be important in counteracting increased α-adrenergic tone, which may limit the blood pressure-lowering effect of β-adrenoreceptor-blockade.
5. Because of these interactions and their pressor potential indomethacin should be used with caution when combined with either diuretics or β-adrenoreceptor blockers.
Central Nervous System Pressor Responses in Rats Susceptible and Resistant to Sodium Chloride Hypertension
Authors: Ikeda T. , Tobian L. , Iwai J. , Goossens Patricia 
Published: August 2015

1. The pressor responses to hypertonic saline and angiotensin II introduced into the left lateral ventricle were both significantly greater in salt-sensitive (S) rats compared with salt-resistant (R) rats, with all rats on a low Na diet.
2. When S rats were given thiazide to nullify the pressor effect of dietary NaCl, their blood pressure averaged only 5 mmHg higher than that of the R rats; nevertheless, these S rats had significantly higher central nervous system pressor responses to angiotensin II and hypertonic saline.
3. Thus, if excessive dietary Na increases blood pressure by way of action on the central nervous system, these heightened pressor responses could partially account for the NaCl hypertension in S rats. Alternatively, depressed central nervous system pressor responses in R rats could partially explain the resistance of R rats to NaCl hypertension.
Sodium and Renin in the Hypertension of Early Renal Disease
Authors: Wong S. F. , Mitchell M. I. , Robson V. , Wilkinson R. 
Published: August 2015

1. Plasma renin activity, response to saralasin and exchangeable sodium have been measured in 43 patients with early renal disease.
2. Blood pressure was directly proportional to plasma renin activity. However, mean plasma renin activity was lower in patients with renal disease than in normal controls.
3. Blood pressure fell in response to saralasin infusion in proportion to the pre-infusion plasma renin activity.
4. Exchangeable sodium in hypertensive patients with renal disease did not exceed that in normotensive patients in contrast to earlier reports. Discrepancies may arise from the difficulty in interpreting measured exchangeable sodium in relation to body build.
Sympathetic and Parasympathetic Components of Reflex Cardiostimulation during Vasodilator Treatment of Hypertension
Authors: in 't Veld A. J. Man , Wenting G. J. , Verhoeven R. P. , Schalekamp M. A. D. H. 
Published: August 2015

1. Haemodynamic responses to diazoxide (300 mg intravenously) were studied in 15 hypertensive patients before and after chronic β-adrenoreceptor blockade by 320 mg of propranolol daily. After diazoxide alone, mean arterial pressure and total peripheral resistance were lowered by 24 ± 3 and 35 ± 5% (mean ± sem) respectively. Cardiac output and heart rate rose by 25 ± 9 and 21 ± 3%. During β-adrenoreceptor blockade, the percentage changes of mean arterial pressure, heart rate, cardiac output and total peripheral resistance after vasodilatation were not significantly different from those after diazoxide alone.
2. Atropine, 0·04 mg/kg body weight, was given to 12 hypertensive patients chronically treated with β-adrenoreceptor blockade, before acute vasodilatation by diazoxide. Diazoxide caused no increase in heart rate after combined β-adrenoreceptor and parasympathetic blockade. However, cardiac output rose by 14 ± 5%.
3. We conclude that withdrawal of parasympathetic tone is an important determinant of circulatory homeostasis after acute vasodilatation during β-adrenoreceptor blockade.
Relation between Prognosis and the Blood Pressure before and during Treatment of Hypertensive Patients
Authors: Beevers D. G. , Johnston J. , Devine B. L. , Dunn F. G. , Larkin H. , Titterington D. M. 
Published: August 2015

1. A study was conducted amongst 1247 treated hypertensive patients to determine the predictive power of untreated baseline and achieved treated blood pressures in the development of the complications of hypertension. In addition the relative importance of systolic and diastolic pressures was calculated.
2. Statistical analysis was done by calculating univariate differences in blood pressure between cases with and without complications. The higher the univariate distance, the greater the predictive power.
3. Blood pressures achieved during treatment were more important than baseline pressures for predicting stroke in both men and women, confirming the benefits of antihypertensive therapy in preventing strokes.
4. There was some evidence of prevention of myocardial infarction in men and of angina in women as a result of therapy.
5. There was no evidence to suggest that any one group of drugs, including β-adrenoreceptor-blocking drugs and thiazides, conferred any extra benefit in preventing coronary heart disease.
6. The systolic blood pressures achieved during treatment predicted stroke better than diastolic pressure, but no consistent trends were found for coronary heart disease.
Side-Effects of Antihypertensive Treatment: A Placebo-Controlled Study
Authors: Bauer G. E. , Baker J. , Hunyor S. N. , Marshall P. 
Published: August 2015

1. A questionnaire, modified from Bulpitt & Dollery (1973), inquired about 20 symptoms commonly associated with hypertension or its drug therapy in 1017 subjects (age 30–69 years). Groups consisted of (a) active therapy, (b) placebo, (c) no tablets, and (d) a non-study control group. The response rate was 96% in the first three groups and 92% in group (d).
2. The subjects in groups (a), (b) and (c) constituted part of a placebo-controlled, patient-blind intervention study in the treatment of mild hypertension (The Australian National Blood Pressure Study).
3. After age/sex adjustment of the data, only sleepiness and self-assessed depression were found to be more common in the actively treated group. Impotence, failure of ejaculation and nocturia were age-related symptoms. Generally, complaint rate was higher in females.
4. The knowledge of a mild hypertensive condition or its modern drug therapy lead to very few symptoms in a non-hospital population who already have a fairly high ‘complaint level’.
Fluorescent Lipid-Peroxidation Products in Synovial Fluid
Authors: Lunec J. , Dormandy T. L. 
Published: August 2015

1. Samples and extracts from synovial effusions were examined for the presence of fluorescent degradation products of free-radical oxidation (peroxidation).
2. Two classes of fluorescent compounds were identified and their fluorescence and physical properties are described. The fluorescence in the aqueous methanol phase of the extracts had the characteristics of conjugated Schiff bases.
3. Changes in synovial fluid and synovial fluid extracts in vitro induced by u.v. irradiation, prolonged incubation and the enzymic generation of oxidizing free radicals, with or without admixed peroxidizing arachidonic acid, and in the absence and presence of antioxidants, suggest that the fluorescent material is derived from peroxidized polyunsaturated lipids in damaged synovial tissue.
Renal Sodium Retention in Cirrhosis: Relation to Aldosterone and Nephron Site
Authors: Wilkinson S. P. , Jowett T. P. , Slater J. D. H. , Arroyo V. , Moodie H. , Williams R. 
Published: August 2015

1. In a group of patients with cirrhosis who showed a wide range of values for the rate of renal sodium excretion, the latter was found to be inversely related to both the plasma concentration and rate of renal excretion of aldosterone. However, for a given sodium excretion the values for aldosterone were significantly lower in the patients than for a group of healthy control subjects. These findings suggest either an increased renal tubular sensitivity to aldosterone or the participation of other factors in the pathogenesis of the sodium retention.
2. Based on measurements of the rate of urine flow and the clearances of free water and inulin during a maximal water diuresis, the fractional reabsorption of sodium by the ‘proximal’, ‘diluting segment’ and ‘distal’ segments of the nephron was estimated. For patients retaining sodium the enhanced reabsorption occurred at both proximal and distal sites, the latter being quantitatively more important. There was no significantly enhanced sodium reabsorption in the diluting segment.
Subcellular Distribution of Radio-Labelled Iron during Intestinal Absorption in Guinea-Pig Enterocytes with Special Reference to the Mitochondrial Localization of the Iron
Authors: Hopkins J. M. P. , Peters T. J. 
Published: August 2015

1. 59Fe-labelled ferric chloride was introduced into tied loops of guinea-pig jejunum.
2. After 5–30 min the loop was removed, the enterocytes were isolated, homogenized and subjected to analytical subcellular fractionation.
3. Uptake of 59Fe was extremely rapid and after 5 min 45% of the radioactivity sedimented in the mitochondrial fraction.
4. Density gradient centrifugation indicated that approximately 80% of this radioactivity was associated with the mitochondria themselves; the remainder was in brush-border fragments.
5. Selective disruption of the mitochondria demonstrates that the iron is localized to the matrix and the inner membrane, indicating transport of the absorbed iron into the organelle.
6. It is suggested that mitochondria are actively implicated at an early stage in the intestinal transport of iron.