bluuebunny/crossref_metadata_2025_split huggingface dataset:
INFLUENCE OF VARIATION IN DIETARY SODIUM INTAKE ON BIOCHEMICAL INDICES OF SYMPATHETIC ACTIVITY IN NORMAL MAN
Authors: Watson R. D. S. , Esler M. D. , Leonard P. , Korner P. I. 
Published: June 2007

SUMMARY1. The effects of variation in dietary sodium intake on biochemical indices of sympathetic activity were investigated in normal subjects.2. Sodium restriction for 7 days (mean urinary sodium excretion 21 mmol/day, s.e.m. =4) increased supine plasma noradrenaline concentration significantly (1.78 nmol/l, s.e.m. =0.23) compared to levels during medium sodium intake (1.31 nmol/l, s.e.m. =0.14) and high sodium intake (1.35 nmol/l, s.e.m. =0.25), when urinary sodium excretion averaged 186 (s.e.m. =24) and 310 (s.e.m. =43) mmol/l respectively. Plasma adrenaline concentrations did not vary significantly.3. During sodium restriction, the apparent release rate of noradrenaline increased significantly; noradrenaline clearance remained unchanged.4. No changes were observed in the heart rate response after β‐adrenoceptor stimulation with isoprenaline, suggesting that increased sympathetic activity during sodium restriction did not necessarily alter cardiac β‐receptor sensitivity.5. The responses to cardiac autonomic blockade with propranolol and atropine did not vary with sodium intake.6. These observations suggest that the sympathetic response to sodium restriction may not be generalized, excluding, in particular, the sympathetic nerves to the heart.
CARDIOVASCULAR EFFECTS OF NEUROMUSCULAR BLOCKADE DURING INDUCED HYPOTHERMIA
Authors: Wyse Richard K. H. , Silove Eric D. , Godley Margaret L. , Welham Kenneth C. 
Published: June 2007

SUMMARY1. Young lambs were used to study the effects of progressive cooling and rewarming on cardiovascular function during neuromuscular blockade induced by gallamine.2. Initially, it was shown that gallamine exerted no immediate, direct haemodynamic effect in normothermic or hypothermic lambs (cooled by 10°C).3. By comparison with hypothermic controls, neuromuscular blockade was associated with increases in left ventricular (LV) max dP/dt (153%; P<0.02) as cooling progressed, and even greater increases (232%; P<0.001) during rewarming. It was concluded that these changes seem likely to represent enhanced myocardial contractility since preload did not closely follow LV max dP/dt (heart rate and mean aortic pressure fell gradually during cooling but values were restored in the rewarming phase).4. LV max dP/dt in lambs given gallamine only after cooling also showed a similar response during rewarming.5. Results of this study may have clinical relevance relating to the mechanical recovery of the hypothermic heart in patients receiving neuromuscular blockade during cardiac surgery, and they argue against using gallamine as such an agent.
A SIMPLE HPLC ASSAY FOR URINARY PARACETAMOL METABOLITES AND ITS USE TO CHARACTERIZE THE C3H MOUSE AS A MODEL FOR PARACETAMOL METABOLISM STUDIES
Authors: Miners John , Adams John F. , Birkett Donald J. 
Published: June 2007

SUMMARY1. A high performance liquid chromatographic (HPLC) assay for unchanged paracetamol and its glucuronide, sulphate, cysteine and mercapturic acid conjugates in the urine of man, mouse and rat is described. The method is simple, rapid and reproducible.2. The metabolite assay has been used to characterize the male C3H mouse, which shows sensitivity to paracetamol toxicity similar to man, as a model for paracetamol metabolism studies.3. In male C3H mice there was no evidence to suggest saturability of the glucuronidation pathway on increasing the paracetamol dose from 50 to 300 mg/kg. By contrast, the metabolic ratio and fractional excretion of both the sulphate and glutathione‐derived conjugates decreased with increasing paracetamol dose.4. For animals administered a 200 mg/kg dose of paracetamol, pretreatment with phenobarbitone or 3‐methylcholanthrene increased the fractional excretion and metabolic ratio of the glutathione‐derived and glucuronic acid conjugates. Piperonyl butoxide pretreatment of animals administered the same dose of paracetamol inhibited glutathione and glucuronic acid conjugation.
EFFECT OF INCREASED BILE FLOW AND BILE ACID SECRETION ON THE HEPATIC ELIMINATION OF SODIUM VALPROATE IN THE CAT
Authors: Marshall A. W. , Mihaly G. W. , Smallwood R. A. , Hanson R. G. , Vajda F. J. E. , Phillips J. , Baldas J. 
Published: June 2007

SUMMARY1. The effect of increased bile flow and hepatic bile acid flux on the systemic clearance and hepatic elimination of intravenously administered sodium valproate was studied in the bile fistula cat. Taurochenodeoxycholic acid (TCDC), tauro‐3α, 7β‐dihydroxy‐12‐keto‐5β‐cholanoic acid (T12K), SC‐2644, and secretin were infused intravenously to vary bile flow and biliary bile acid secretion. Control animals were infused with 0.15 mol/l NaCl.2. Less than 1% of the drug administered to controls appeared as unchanged valproate in the bile over 6 h. Although SC‐2644, T12K, and secretin significantly increased biliary excretion of valproate, it did not exceed 2% of the intravenous dose. Biliary clearance was directly related to the rate of bile flow, but not to the bile acid flux.3. By contrast, 18–19% of the dose appeared in bile as metabolite in controls, and none of the choleretic agents significantly increased this percentage. As a result, systemic clearance of valproate was unaltered.4. We conclude that the movement of unchanged valproate into bile is consistent with a process of simple diffusion. The fact that choleretic agents do not increase metabolite excretion into bile suggests that metabolite formation may be the rate‐limiting step in the hepatic elimination of valproate, rather than transport and excretion of metabolites into bile.
ERYTHROCYTE CATION TRANSPORT DISTURBANCES IN PATIENTS WITH ENDOGENOUS DEPRESSION
Authors: Rybakowski Janusz , Potok Elżzbieta , Strzyżewski Włlodzimierz , Nowakowska Cecylia 
Published: June 2007

SUMMARY1. The active cation transport mechanisms (ouabain‐dependent fluxes of sodium; ODS) and potassium (ODK), sodium‐potassium adenosine triphosphatase ([Na+‐K+]‐ATPase) activity as well as lithium‐sodium countertransport (LSC) reflecting sodium exchange diffusion, were studied in erythrocytes of forty‐four patients with endogenous depression both in acute episode and in remission, and compared with thirty healthy control subjects.2. During depressive episodes, the activities of all mechanisms studied were significantly lower than those of control subjects. In female depressives the values of ODS and LSC were lower than in males.3. In remission, the activity of all mechanisms rose, reaching in most patients the values of control subjects. In female patients, activities of ODS and LSC were still lower than in male patients and female controls.4. The activities of ODS and LSC had the highest discriminating power between depressive patients and control subjects.5. It appears that membrane pathology may be an aetiologic factor in endogenous depression. A disturbance in erythrocyte transport presents most conspicuously during depressive episodes and in some patients may also persist to the normothymic period.
SODIUM DETECTION THRESHOLD AND PREFERENCE FOR SODIUM CHLORIDE IN HUMANS ON HIGH AND LOW SODIUM DIETS
Authors: DiNicolantonio R. , Teow B. H. , Morgan T. O. 
Published: June 2007

SUMMARY1. Sodium detection threshold and preference for sodium chloride was examined in human volunteers on 2 week periods of high and low salt diets.2. There was no significant difference in salivary electrolytes or sodium detection threshold between the high and low salt diet periods.3. Sodium preference, defined as the final sodium concentration of unsalted tomato juice following the ad libitum addition of NaCl, was significantly less on the low salt diet when compared to the high salt period.4. These results suggest that short periods of dietary salt modification can result in marked shifts in preference for NaCl in the absence of changes in the physiological parameters measured.
SEROTONIN ENHANCES SYMPATHETIC VASOCONSTRICTOR RESPONSES IN RAT ISOLATED PERFUSED TAIL ARTERY BY ACTIVATION OF POSTJUNCTIONAL SEROTONIN‐2 RECEPTORS
Authors: Medgett Iain C. , Fearn Herbert J. , Rand Michael J. 
Published: June 2007

SUMMARY1. The effects of serotonin and the selective serotonin‐2 receptor antagonist ketanserin have been investigated on sympathetic vasoconstrictor responses in rat isolated perfused/superfused proximal tail artery segments.2. Serotonin (6 nmol/l) markedly enhanced responses to low frequency, short duration electrical stimulation (0.1 ms pulses at 1 Hz for 10 s).3. Serotonin (6 nmol/1) had a very slight (<10 mmHg) direct vasconstrictor effect.4. Both the enhancing effect of serotonin on responses to electrical stimulation and the slight direct vasoconstrictor effect were blocked by ketanserin (3 nmol/l).5. Ketanserin (3 nmol/l) had no significant effect on resting tone or on responses to electrical stimulation.6. It is concluded that serotonin enhances sympathetic vasoconstrictor responses in rat tail artery by activation of postjunctional serotonin‐2 receptors. Blockade of this effect by ketanserin is entirely consistent with its antihypertensive effect in vivo.
MODERATE SODIUM RESTRICTION AND POTASSIUM SUPPLEMENTATION IN ESSENTIAL HYPERTENSION
Authors: Richards A. Mark , Nicholls M. Gary , Espiner Eric A. , Ikram Hamid , Maslowski Andrew H. , Hamilton Eric J. , Wells J. Elisabeth 
Published: June 2007

SUMMARY1. Continuous 24 h arterial blood pressure and vasoactive hormones were measured in twelve patients with essential hypertension after 4 weeks on a control sodium intake (180 mmol/day) and after similar periods of sodium restriction (80 mmol/day) and potassium supplementation (200 mmol/day).2. Sodium restriction was associated with variable blood pressure changes in individual patients and a small reduction in 24 h mean pressure of 4/3 mmHg.3. The greatest fall in blood pressure with sodium restriction was seen in those patients with the least rise in renin.4. Potassium supplementation was associated with variable individual blood pressure changes and a trivial reduction in mean 24 h pressures (0.1/0.8 mmHg).5. Mean 24 h plasma aldosterone concentration was significantly higher during sodium restricted and potassium‐supplemented diets, compared to control levels, but other vasoactive hormones were unchanged.
CONCERN ABOUT GAIN: IS THIS THE BEST MEASURE OF PERFORMANCE OF CARDIOVASCULAR REFLEXES?
Authors: Ludbrook John 
Published: June 2007

SUMMARY1. Open‐loop gain is commonly used as a measure of the effectiveness of cardiovascular reflex control systems.2. There is no evidence that directly measured baroreflex gain for heart rate gives useful information about blood pressure control in human or experimental hypertension.3. Calculation of open‐loop gain for blood pressure from closed‐loop observations requires many assumptions to be made.4. Calculation of the independent and interactive effects of reflex inputs by factorial analysis may be more versatile, and give a more useful expression of the actions and interactions of cardiovascular reflexes in response to physiological disturbances, than does the calculation of gain.
ADJUNCTIVE EFFECT OF SALT RESTRICTION ON ANTIHYPERTENSIVE EFFICACY
Authors: Gillies A. H. B. , Carney S. L. , Smith A. J. , Waga S. M. 
Published: June 2007

SUMMARY1. The effect of dietary salt restriction on blood pressure was measured in patients with moderate hypertension receiving antihypertensive medication. Patients were studied during a randomly allocated 6 week period of moderate dietary salt restriction and during a 6 week period of normal diet.2. Twenty‐four of twenty‐eight patients achieved a reduction of salt excretion exceeding 20%. In these patients mean urinary sodium excretion fell from 169 (s.e.m. = 13) mmol/24 h to 92 (s.e.m. = 7) mmol/24 h. Potassium excretion and body weight did not change, and with the exception of the erect systolic pressure, there was no overall change in blood pressure.3. When the data were grouped according to the patient medication, mean supine systolic pressure fell from 148.9 (s.e.m. = 4.4) to 140.3 (s.e.m. = 5.0) mmHg (n= 14, P>0.05) and mean supine diastolic pressure fell from 100.8 (s.e.m. = 2.9) to 97.0 (s.e.m. = 2.8) mmHg (n= 14, P>0.05) in patients taking diuretics. Blood pressure did not change in patients whose medication did not include diuretics.4. Moderate dietary salt restriction may be therapeutically useful in patients with moderate hypertension treated with diuretics but is of little value in those not receiving diuretics.
DEMONSTRATION OF PROXIMAL TUBULAR α‐ADRENOCEPTORS IN VIVO
Authors: Woodcock Elizabeth A. , McLeod Jennifer K. , Johnston Colin I. 
Published: June 2007

SUMMARY1. Receptors for parathyroid hormone (PTH) in the renal tubule are coupled to adenylate cyclase stimulation. PTH causes a rise in urinary cAMP by leakage from cells of the proximal convoluted tubule.2. The effects of α‐adrenergic agonists and antagonists on the urinary cAMP response to PTH were investigated in anaesthetized rats in vivo. Injection of PTH (15 u/kg i.v.) produced an increase in urinary cAMP from 1.7 (s.e.m. = 0.3, n= 6) to 7.47 (s.e.m. =0.7, n=6) nmol cAMP/μmol creatinine in 30 min urine samples. Infusion of the α2‐adrenoceptor agonist clonidine at 1 μg/kg per min caused a decrease in the cAMP response to PTH to 3.6 (s.e.m. =0.5, n= 12) nmol cAMP/μmol creatinine. Infusion of the α2‐selective catecholamine α‐methylnoradrenaline (1 μg/kg per min) caused a similar reduction in urinary cAMP response to that observed with clonidine.3. The α‐adrenoceptor antagonist phentolamine (100 μg/kg per min) enhanced the cAMP response to PTH and reversed the decreased response caused by clonidine.4. These results demonstrate the presence of α‐receptors in the rat proximal convoluted tubule which oppose the actions of PTH in vivo.
RENAL VENOUS RENIN RATIO AS A PREDICTOR OF IMPROVEMENT IN HYPERTENSION FOLLOWING NEPHRECTOMY FOR UNILATERAL RENAL DISEASE
Authors: Gordon R. D. , Tunny T. J. , Evans E. B. , Fisher P. M. , Jackson R. V. 
Published: June 2007

SUMMARY1. Renal venous renin ratio (RVRR) was measured in twenty hypertensive patients before removal of a kidney for unilateral, parenchymal renal disease. They were then followed for 1.3–9 y.2. Hypertension was cured or improved in six of eight patients with positive unstimulated and stimulated ratios, in none of five whose ratios became positive only on stimulation, and in one of seven with all ratios negative.3. Patients improved or cured by surgery had a significantly shorter duration of hypertension and a significantly lower serum creatinine after nephrectomy.4. Unstimulated RVRR was a reliable predictor of the effect of unilateral nephrectomy on blood pressure level.
THE USE OF A RAT ISOLATED ILEAL PREPARATION TO INVESTIGATE THE RELEASE OF NEUROTENSIN
Authors: Gill S. S. , Lee Y. C. , Ghatei M. A. , Ghiglione M. , Uttenthal L. O. , Bloom S. R. 
Published: June 2007

SUMMARY1. An isolated and perfused preparation of rat ileum was used to investigate the effects of cholinergic, adrenergic and bombesin stimuli on neurotensin release into the vascular compartment.2. A vigorous release of neurotensin like immunoreactivity (NTLI) to 200% above basal values in response to intraluminal infusions of emulsified soybean oil (Intralipid) demonstrated the physiological responsiveness of the preparation.3. Carbachol significantly stimulated the release of both NTLI and bombesin like immunoreactivity (BLI), with maximal responses at 5 times 10‐9 mol/l carbachol of 100% and 400% above basal values for NTLI and BLI, respectively.4. Noradrenaline at 10‐6 and 10‐4 mol/l caused no significant release of NTLI but markedly inhibited spontaneous BLI release.5. Synthetic amphibian bombesin caused a marked release of NTLI to 81% and 100% above basal at infusion concentrations of 5 times 10‐11 and 5 times 10‐10 mol/l respectively.6. These results suggest that there is either a direct effect of cholinergic agents on the N cells bringing about NTLI release, or an indirect effect via the release of bombesin like peptides from intrinsic gut neurones. This preparation provides a useful model to study the complex neural, paracrine and endocrine interactions in the gastrointestinal tract.
THE EFFECT OF QUATERNARY NALOXONE ON THE INCREASED NALOXONE POTENCY INDUCED BY MORPHINE
Authors: Wong Chak‐Lam , Wai Man‐Keung 
Published: June 2007

SUMMARY1. Using the abdominal constriction test in mice it was shown that the antinociceptive effect of morphine was inhibited by naloxone hydrochloride and its quaternary derivative naloxone methylbromide which presumably only acts peripherally.2. Pretreatment with a single dose of morphine 2.0 mg/kg s.c. did not alter the antinociceptive effect of a second dose of morphine given 3 h later. However, the antagonistic effect of naloxone against morphine was enhanced at this time.3. The development of increased naloxone potency was inhibited when naloxone hydrochloride was given together with morphine in the pretreatment.4. A similar inhibitory effect was observed when the quarternary derivative naloxone methylbromide was used instead of naloxone hydrochloride in the pretreatment regime.5. As there was no difference between the effects of naloxone hydrochloride and naloxone methylbromide in suppressing the development of increased naloxone potency induced by morphine pretreatment, it was concluded that this phenomenon may be mediated mainly through peripheral opiate receptors.
DIURETIC AND HAEMODYNAMIC EFFECTS OF MK 447 IN NORMOTENSIVE AND HYPERTENSIVE SHEEP
Authors: Humphery T. J. , Coghlan J. P. , Denton D. A. , Fei D. W. T. , Graham W. F. , Scoggins B. A. , Whitworth J. A. 
Published: June 2007

SUMMARY1. The short term effects of the novel diuretic MK 447 were examined in both normotensive and hypertensive (ACTH treated) conscious sheep.2. The drug had profound diuretic, natriuretic and kaliuretic effects in both groups. Plasma sodium was unchanged but plasma potassium fell and haematocrit increased. Plasma renin concentration increased with MK 447 in the normotensive but not the hypertensive sheep.3. In the normotensive sheep cardiac output fell, peripheral resistance increased and blood pressure was unchanged. In the hypertensive ACTH treated sheep cardiac output and blood pressure fell but resistance was unchanged.
EFFECTS OF THYROXINE TREATMENT ON CONTRACTIONS OF SOLEUS MUSCLES OF ANAESTHETIZED CATS
Authors: Merican Zainuddin , Morat Paden 
Published: June 2007

SUMMARY1. The effects of chronic thyroxine treatment on cat soleus muscle contractions were studied.2. Maximum twitch tension, contraction time, half relaxation time and tensiontime integral of maximal twitches of the soleus muscles of thyroxine treated cats were significantly decreased. Consequently, there was a decrease in tension and degree of fusion of incomplete tetanic contractions of the soleus muscle. The maximum tetanic tension was not statistically significantly changed, suggesting that the effects may be due to a decrease in the duration of the active state of the muscle.3. Isoprenaline given intravenously during incomplete tetanic contractions of the soleus muscle caused a statistically significant depression of tension in the control group but not in the thyroxine treated group. This further suggests reduction in the duration of the active state of soleus muscles of thyroxine treated cats.4. Propranolol injected chronically with thyroxine reversed or prevented the depression of tension caused by thyroxine treatment, suggesting the involvement of β‐adrenoceptors in these effects.5. The decrease in tension and degree of fusion during incomplete tetanic contractions of the thyroxine treated soleus could be responsible, at least partly, for the muscle weakness and tremor of thyrotoxicosis. Cyclic AMP may possibly be the mediator of these effects.
EFFECT OF DIETARY UREA ON BLOOD PRESSURE IN SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Wang Hong , Ikeda Katsumi , Kihara Masahiro , Nara Yasuo , Horie Ryoichi , Yamori Yukio 
Published: June 2007

SUMMARY1. The feeding of a normal diet containing 13.5% urea (in place of protein in a high protein diet) attenuated the development of severe hypertension and decreased the incidence of stroke in spontaneously hypertensive rats (SHR), when 1% NaCl solution was given to them.2. The urea not only increased urine volume, but also increased urinary sodium excretion in SHR given 1% NaCl for drinking.3. Although there was no obvious difference in erythrocyte size between the urea and the control groups, there was a significant inverse correlation between plasma urea level and erythrocyte size.4. These results suggest that a high protein diet reduced blood pressure partly through the diuretic effect of urea, the common metabolite of various proteins.
EFFECTS OF β‐ADRENOCEPTOR BLOCKADE ON PROSTACYCLIN MEDIATED RENIN RELEASE IN SHEEP
Authors: Mason R. T. , Coghlan J. P. , Denton D. A. , Fei D. W. T. , Whitworth J. A. , Scoggins B. A. 
Published: June 2007

SUMMARY1. The effect of prostacyclin (PGI2) infusion on plasma renin concentration (PRC) was examined before and after propranolol treatment in sheep.2. Increasing doses of prostacyclin (0.05, 0.1 or 0.3 μg/kg per min) produced dose dependent increases in PRC.3. There was a significantly lower PRC response after propranolol at 0.3 μg/kg per min only.
CANINE NONRESPONDERS TO ALVEOLAR HYPOXIC VASOCONSTRICTION AND QUANTITATIVE RESTORATION OF THE RESPONSE BY ASPIRIN I‐3
Authors: Siefkin Allan D. , Parsons Gibbe H. 
Published: June 2007

SUMMARY1. Hypoxic pulmonary vasoconstriction is characterized by considerable variability in rate of response (pulmonary vascular resistance [PVR] as a function of time under hypoxia). To further define this response, forty‐five closed chest dogs were anaesthetized (pentobarbitone sodium), intubated, and mechanically ventilated. Constant left lower lobar pulmonary artery flow was maintained through a balloon tipped 14F catheter via an extracorporeal pump at a rate to achieve lobar pulmonary artery pressure (Plobar) equal to main pulmonary artery pressure (Ppa) and thereafter held constant. Left ventricular end diastolic pressure (Plved) was measured by left ventricular catheter and lobar pulmonary artery flow rate (Q) by flow meter. Lobar PVR (mmHg/min per 1) was calculated every 15 min.2. Ventilation with 10% oxygen (O2) separated two groups based on the increase in PVR over time: twenty‐two rapid hypoxic responders [HR] (slope =ΔPVR/Δmin>0.3) and twenty‐three slow or nonresponders [NR] (slope < 0.1). The twenty‐three NR were divided into two groups. Ten NR dogs (NR control) had no change in mean PVR (23.9, s.d. = 8.2, to 24.1, s.d. = 9.6) over a mean of 78 min and were used as controls. Thirteen NR dogs (NR ASA) had no change in mean PVR (32.9, s.d. = 9.5, to 32.3, s.d. = 9.8) over 75 min and were given aspirin (ASA), 10–15 mg/kg intra‐arterially. The NR ASA group mean PVR then increased from 32.3 (s.d. = 9.8) to 59.1 (s.d. = 23.9, 82.9% increase, P < 0.01) over a mean of 54 min. The mean PVR for the twenty‐two HR rose from 39.8 (s.d. = 34.0) to 64.5 (s.d. = 36.6, 62.1% increase, P<0.01) over a mean of 72 min. The slopes of rate of response for HR (0.66) and for NR ASA (0.88) were not significantly different. The absolute values of PVR reached after plateau for HR and for NR ASA (after ASA) were also not different.3. Aspirin restored the NR capability to develop pulmonary vasoconstriction in response to alveolar hypoxia. The rate of response and the absolute level of response reached were also restored by aspirin.