bluuebunny/crossref_metadata_2025_split huggingface dataset:
INFLUENCE OF ENDOTHELIUM ON NORADRENALINE‐INDUCED VASOCONSTRICTION IN RABBIT CENTRAL EAR ARTERY
Authors: Verrecchia C. , Sercombe R. , Seylaz J. 
Published: June 2007

SUMMARY1. The effects of removing the endothelium of the rabbit central ear artery on the response to noradrenaline have been examined in vitro.2. A 10 mm segment of this artery was cannulated and connected to a constant flow perfusion circuit; the endothelium of some arteries was first removed mechanically. Vasomotor activity was determined by measuring the pressure at the input to the artery.3. Scanning electron microscopy, light microscopy and functional test with acetylcholine on intact and rubbed arteries showed that the endothelium had been effectively removed in lesioned arteries and remained intact in control arteries throughout the experiment.4. Internal or external noradrenaline‐induced a concentration‐dependent constriction which was significantly greater in the rubbed arteries.5. In contrast, there was no significant difference in the pressure/flow curves of control and rubbed arteries whether preconstricted with K+ or not.6. We conclude that the endothelium in the rabbit isolated ear artery greatly influences the response to internal or external noradrenaline, and that this effect cannot be explained by changes in the physical characteristics of de‐endothelialized arteries. The endothelium thus may play an inhibitory role in noradrenaline‐induced vasoconstrictions.
ROLE OF CARDIAC AND VASCULAR AMPLIFIERS IN THE MAINTENANCE OF HYPERTENSION AND THE EFFECT OF REVERSAL OF CARDIOVASCULAR HYPERTROPHY
Authors: Korner P. I. , Jennings G. L. , Esler M. D. , Broughton A. 
Published: June 2007

SUMMARY1. Changes in amplifying capacities of the hypertrophied heart and resistance vessels account for the characteristic evolution of haemodynamic patterns in the course of essential hypertension.2. Reversal of hypertrophy in established essential hypertension requires prolonged control of blood pressure. Redevelopment of hypertension on stopping drug therapy is slowest if there has been reversal of both vascular and cardiac hypertrophy. It may be possible to subsequently maintain normal blood pressure in a proportion of patients by non‐pharmacological means following the initial period of drug therapy.3. Preliminary findings suggest that in a majority of patients the sympathetic nervous system may be overactive, whilst a smaller subset may have dysfunction of volume regulation.
IS ALDOSTERONE/RENIN RATIO USEFUL TO SCREEN A HYPERTENSIVE POPULATION FOR PRIMARY ALDOSTERONISM?
Authors: Hamlet S. M. , Tunny T. J. , Woodland E. , Gordon R. D. 
Published: June 2007

SUMMARY1. The ratio of aldosterone to renin in plasma was measured in samples collected from 79 hypertensive patients.2. Eighteen patients with primary aldosteronism had ratios ranging from 25 to 677 (mean 183) when measured on 34 occasions, while 16 normal subjects had ratios of 3.3–21 (mean 11.3).3. Of the remaining 61 patients with ratios ranging from 1.8 to 184, 15 patients have ratios greater than 25 and are under investigation for primary aldosteronsim, which appears highly likely in five and has been excluded in two.4. The aldosterone/renin ratio appears promising as a screening test for primary aldosteronism. Consistency and the effects of sodium and potassium balance and of antihypertensive medications require further study.
INCREASED RENAL PROSTANOID SYNTHESIS AFTER UNCLIPPING THE ONE‐KIDNEY, ONE‐CLIP HYPERTENSIVE RAT: EFFECT OF RENAL DENERVATION
Authors: McGowan Helen , Anderson Helen , Barden Anne , Vandongen Robert 
Published: June 2007

SUMMARY1. Renal denervation of hypertensive one‐kidney, one‐clip (1K, 1C) rats resulted in a minor fall in blood pressure (216, s.e.m. = 4, to 182, s.e.m. =4, mmHg) 24 h later, which returned to predenervation levels within 1 week.2. Subsequent unclipping led to a similar fall in blood pressure in denervated (202, s.e.m. = 4 to 142, s.e.m. = 3) and sham‐denervated (211, s.e.m. = 5 to 147, s.e.m. = 4) rats.3. Unclipping also resulted in a marked rise in urinary PGE2 and 6‐keto PFG1α in both denervated and sham‐denervated animals.4. It appears that 1K, 1C hypertension, 8 weeks after clipping, is only slightly dependent on renal nerves.5. Unclipping results in increased renal synthesis of PGE2 and PGI2 which is not dependent on intact renal innervation.
BLOOD PRESSURE RESPONSES TO DIETARY SODIUM MANIPULATION DURING NORMOTENSIVE HUMAN PREGNANCY
Authors: McEniery P. J. , Hunyor S. N. , Cooper K. A. , Gallery E. D. M. , Gyory A. Z. , Boyce† E. S. 
Published: June 2007

SUMMARY1. Short‐term salt loading and salt restriction in a group of normal pregnant women produced no changes in lying, sitting or standing blood pressures or heart rates.2. Home blood pressures showed no trend to change over the periods of altered salt intake.3. Although plasma volume and plasma renin activity changed with altered salt intake, there were no relationships between changes in these parameters and changes in mean arterial pressures (MAP) between the low and high salt diets.4. Capillary permeability and echocardiographic dimensions were unchanged by salt intake once sodium balance had been established.
ACUTE TOLERANCE TO DIAZEPAM INDUCED BY BENZODIAZEPINES
Authors: Wong P. T. ‐H. , Yoong Y. L. , Gwee M. C. E. 
Published: June 2007

SUMMARY1. It was observed that the effectiveness of diazepam in causing sleep, as denned by the loss of righting reflex, was significantly decreased after a single exposure to either diazepam or lorazepam.2. RO 15‐1788, a benzodiazepine antagonist, in contrast did not induce tolerance to diazepam. The mechanism for this acute tolerance is unclear. The rapidity in its development may exclude metabolic tolerance while alterations in brain sensitivity to diazepam remain a possibility.
EFFECTS OF ACUTE VERSUS CHRONIC DELETION OF ARTERIAL BARORECEPTOR INPUT ON THE CARDIOVASCULAR RESPONSES TO EXERCISE IN THE RABBIT
Authors: Ludbrook John , Graham William F. , Potocnik Simon J. 
Published: June 2007

SUMMARY1. These experiments were designed to confirm that at the onset of treadmill exercise in rabbits the tonic reflex depressor effects of input to the central nervous system from arterial baroreceptors is abolished, thus contributing to the rise of systemic arterial pressure (SAP) and heart rate (HR).2. An inflatable cuff was placed around one common carotid artery after the remaining arterial baroreceptors had been surgically denervated. Transient inflation of the cuff caused reflex rises of SAP and HR, which were much reduced during the first minute of exercise. Deflation of the cuff caused a brisk fall of HR, which was completely abolished by exercise.3. A snare was placed around one carotid sinus nerve after the remaining arterial baroreceptors had been surgically denervated. Where the snare was tightened all arterial baroreceptor reflexes were immediately and permanently abolished. This allowed the reflex effects of baroreceptor input to be calculated by difference. The magnitude of these calculated effects, at rest and during exercise, diminished according to how long after barodenervation the observations were made.4. We conclude from the above experiments that the resting tonic reflex depression of SAP and HR caused by baroreceptor input is much reduced, rather than completely abolished, at the onset of exercise.5. We also conclude, from the effects of partial surgical barodenervation, and of unloading the carotid baroreceptors prior to exercise by inflating the carotid cuff, that resting input from the arterial baroreceptors must be near zero before the cardiovascular response to exercise is grossly altered.
PREVENTION AND REVERSAL OF OUABAIN‐INDUCED CARDIOTOXICITY BY NALOXONE IN THE GUINEA‐PIG
Authors: Lee A. Y. S. , Unang T. W. K. , Wong T. M. 
Published: June 2007

SUMMARY1. The effects of pre‐ and post‐treatment with naloxone on the cardiotoxicity of ouabain in the guinea‐pig were studied.2. After pretreatment with naloxone, the dose of ouabain required to induce ventricular arrhythmias and cardiac arrest were significantly increased, in a dose‐dependent manner, compared with the control, indicating a protective effect of naloxone against digitalis intoxication.3. Administration of naloxone at the onset of cardiac arrhythmias induced by a lethal dose of ouabain restored the cardiac rhythm and consequently saved life in seven out of eight animals, indicating an antiarrhythmic effect of naloxone in digitalis‐intoxicated guinea‐pigs.4. The protective and antiarrhythmic effects of naloxone against digitalis intoxication have clinical implications.
COMPARISON OF THE INHIBITORY EFFECTS OF SPERMINE, PAPAVERINE AND ADRENALINE UPON ISOLATED SEGMENTS OF THE RAT SMALL INTESTINE
Authors: Martin John S. , Tansy Martin F. 
Published: June 2007

SUMMARY1. In the rat isolated duodenal and ileal segments the active baseline force and spontaneous contractile frequency were inhibited by spermine; the relative potencies, estimated as an ED50, were adrenaline papaverine spermine. The changes in baseline force, but not frequency, due to spermine were sensitive to increased calcium.2. The duodenum was always more sensitive to papaverine and adrenaline, but the relative sensitivities of the duodenum and ileum were essentially equal for spermine.3. Inasmuch as the gastrointestinal mucosa of most species contains an abundance of polyamines, these results suggest that, in its free form, spermine may subserve a functional role in the inhibition of gastrointestinal motility.
INTERACTION BETWEEN PLATELET‐RELEASED SEROTONIN AND THROMBOXANE A2 ON HUMAN DIGITAL ARTERIES
Authors: Young M. S. , Iwanov V. , Moulds R. F. W. 
Published: June 2007

SUMMARY1. Synergism between the contractile effects of platelet‐derived serotonin (5HT) and thromboxane A2 (TXA2) on a human blood vessel has been investigated by incubating strips of digital arteries in subcontractile concentrations of either 5HT or the TXA2‐mimetic agent U46619.2. Either agonist U46619 or 5HT, in subcontractile concentrations, significantly potentiated the contractile response to the other.3. The 5HT antagonist ketanserin (10 (μmol/1), theCa2+ antagonist drugs verapamil (3 μmol/l), or nifedipine (10 nmol/l), or a Ca2+‐free bathing medium, reduced the contractile responses to 5HT, but had no effect on the potentiation mediated by U46619.4. The interaction between TXA2 and 5HT derived from platelets was studied by measuring responses to platelets 1 min after aggregation (in the absence or the presence of ketanserin 10 μmol/l), and 20 min after aggregation. The results indicated that the response to platelets mediated by TXA2 and 5HT was greater than the sum of those mediated by TXA2 or 5HT separately.5. It is concluded that synergism between the contractile effects of 5HT and U46619 occurs in human blood vessels; that this is mediated by enhanced utilization of intracellular, rather than extracellular calcium; and that synergism can also occur when 5HT and TXA2 are released from stimulated human platelets.
NEUROMUSCULAR BLOCKING ACTIVITY OF A CRUDE AQUEOUS EXTRACT OF IPOMOEA FISTULOSA
Authors: Abdelhadi A. A. , Elkheir Y. M. , Hassan T. , Mustafa A. A. 
Published: June 2007

SUMMARY1. The rat phrenic nerve hemidiaphragm and chick biventer‐cervicis preparations were used to investigate the effect of a crude aqueous extract of Ipomoea fistulosa.2. Electrically‐induced skeletal muscle twitches of the hemidiaphragm were blocked by the extract and by tubocurarine.3. The anticholinesterase, physostigmine, intensified the blockade by the extract.4. The extract produced contracting of the chick biventer‐cervicis preparation.5. It is suggested that the extract possesses neuromuscular blocking activity of a depolarizing nature.
DISTINGUISHING ALDOSTERONE‐PRODUCING ADENOMA FROM OTHER FORMS OF HYPERALDOSTERONISM AND LATERALIZING THE TUMOUR PRE‐OPERATIVELY
Authors: Gordon R. D. , Hamlet S. M. , Tunny T. J. , Gomez‐Sanchez C. E. , Jayasinghed̊ L. S. 
Published: June 2007

SUMMARY1. In 14 hypertensive patients aldosterone/cortisol ratio was always lower in a peripheral vein or low IVC than in either adrenal vein. In four patients with a right‐sided aldosterone‐producing adenoma (APA), the aldosterone/cortisol ratio in peripheral vein was always higher than in the left adrenal vein. If only the left adrenal vein is cannulated, right‐sided APA can still be diagnosed with certainty.2. In three patients with glucocorticoid‐suppressible hyperaldosteronism, urinary excretion of both 18‐oxocortisol and 18‐hydroxycortisol was elevated. In four patients with APA excretion of 18‐oxocortisol was elevated. In two of three patients with bilateral adrenal hyperplasia (BH), excretion of both steroids was normal.3. 75Se‐selenomethylcholesterol scanning correctly lateralized five APA, but falsely lateralized a patient with BH. Results with CT scans were often misleading.
OMEPRAZOLE: EFFECTS ON OXIDATIVE DRUG METABOLISM IN THE RAT
Authors: Henry D. A. , Gerkens J. F. , Brent P. J. , Dosen P. J. 
Published: June 2007

SUMMARY1. Omeprazole, a substituted benzimidazole and a potent gastric antisecretory drug has been tested for inhibition of microsomal drug oxidative function in the rat.2. A single dose of 40 mg/kg prolonged pentobarbitone sleeping times from 118 (range 73–168) min to 195 (159–222) min (P < 0.01), pentobarbitone half‐lives from 89 (63–114) to 112 (54–146) min (P < 0.05) and aminopyrine breath 14CO2 half‐lives from 43 (37–51) to 56 (49–79) min (P < 0.05). Omeprazole in doses of 20 mg/kg or less had no significant effect.3. In prolonging pentobarbitone sleeping times omeprazole 40 mg/kg and an equimolar (30 mg/kg) dose of cimetidine were approximately equipotent.4. These results contrast with studies in man in which much smaller doses of omeprazole have been shown to produce clinically significant inhibition of drug metabolism.
EFFECTS OF THREE PURINE‐RELATED COMPOUNDS ON PANCREATIC EXOCRINE SECRETION IN THE DOG
Authors: Yamagishi F. , Homma N. , Haruta K. , Iwatsuki K. , Chiba S. 
Published: June 2007

SUMMARY1. The effects of adenosine, adenosine 5′‐triphosphate (ATP) and inosine on pancreatic exocrine secretion were investigated in the vascularly isolated and self‐hacmoperfused dog pancreas. Drugs were injected close‐arterially (i.a.) in a single bolus.2. These three purine‐related compounds per se did not affect resting rate of pancreatic secretion and the concentrations of protein and bicarbonate in the resting juice.3. Graded doses of adenosine (0.1–1.0 mg, i.a.) and ATP (0.1–1.0 mg, i.a.) administered 1 min prior to secretin (0.025 clinical units, i.a.) increased a secretin‐stimulated secretory volume dose‐dependently, and the effects of adenosine and ATP were reversed by pretreatments with theophylline (0.3 mg, i.a.).4. Insoine (1.0 mg, i.a.) affected neither secretin‐ nor dopamine‐stimulated (3 μg, i.a.) pancreatic secretion. Adenosine and ATP did not affect dopamine‐stimulated pancreatic secretion.5. These results suggest that adenosine and ATP (or terminal phosphate hydrolyzed derivatives) enhance secretin‐stimulated pancreatic exocrine secretion through ‘P1’ purine receptors in the exocrine cells, without conversion to inosine.
EFFECTS OF AROTINOLOL, AN α‐ AND β‐ADRENOCEPTOR ANTAGONIST, ON RENIN RELEASE FROM RAT KIDNEY CORTICAL SLICES
Authors: Morimoto S. , Miyawaki N. , Sasaki Y. , Matsumura Y. 
Published: June 2007

SUMMARY1. The effects of arotinolol on changes in renin release in rat kidney cortical slices in response to isoproterenol (IP) or norepinephrine (NE), were studied in comparison with those of AC‐623, a main metabolite of arotinolol, and other typical adrenoceptor antagonists.2. Arotinolol, at concentrations of 10−8 to 10−4 mol/l, inhibited the increasing effect of 10−6 mol/l IP on renin release, in a concentration‐dependent manner. Similar results were observed with AC‐623, propranolol or labetalol, although the inhibitory potencies of these agents were considerably lower than that of arotinolol.3. The blocking effect of arotinolol on the 10−5 mol/l NE‐induced decrease in renin release was much less potent than seen with other α‐adrenoceptor blocking agents such as prazosin, phenoxybenzamine and labetalol.4. These data suggest that the potent blocking effects of arotinolol and its metabolite on the increased renin release in response to β‐adrenoceptor stimulation may contribute to the antihypertensive effect of this agent.
LIPEMIC AND LIPOPROTEINEMIC EFFECTS OF NATURAL AND SYNTHETIC ANDROGENS IN HUMANS
Authors: Crist D. M. , Peake G. T. , Stackpole P. J. 
Published: June 2007

SUMMARY1. Testosterone cypionate administration in weight‐trained subjects reduced serum high‐density lipoprotein cholesterol (HDL‐C) levels without affecting the total cholesterol (Total‐C)/HDL‐C ratio. Nandrolone decanoate administration also reduced HDL‐C levels, but elevated the Total‐C/HDL‐C ratio.2. These findings could not be attributed to changes in exercise patterns, dietary intake, or alcohol consumption.3. It is concluded that the synthetic androgen employed in this study produced a worsening of potential lipid‐related risk factors for ischemic heart disease and that exogenous testosterone has a much less pronounced effect on such risk factors.
CIMETIDINE AND RANITIDINE: A STUDY OF COMPETITIVE AND ION‐CHANNEL BLOCKADE IN THE TOAD ISOLATED RECTUS ABDOMINIS MUSCLE
Authors: Gwee M. C. E. , Cheah L. S. , Shoon M. L. 
Published: June 2007

SUMMARY1. Responses of the toad isolated rectus abdominis muscle to cumulative doses of carbachol were recorded in the absence or presence of varying concentrations of cimetidine or ranitidine. The corresponding cumulative log concentration‐response curves for carbachol were then plotted for each antagonist studied.2. Cimetidine (1 mmol/1) produced a straight and parallel 1.8‐fold shift of the carbachol curve to the right of the corresponding control curve with no significant change in the maximal response.3. Cimetidine, at doses of 2.5 mmol/1 and 5 mmol/1, and ranitidine, at doses of 0.1 mmol/1, 0.25 mmol/1 and 0.5 mmol/1, produced a concentration‐dependent and non‐parallel shift of the carbachol curve to the right of the corresponding control curve accompanied by a marked decline of maximal responses.4. The results provide further evidence that ion‐channel block may be involved in the neuromuscular blockade produced by cimetidine or ranitidine, the latter being more potent in this respect. Competitive antagonism may also be partly responsible for cimetidine‐induced neuromuscular blockade, especially at lower drug concentrations.
ALDOSTERONE RESPONSES TO ACTH DURING HYPOXIA IN CONSCIOUS RATS
Authors: Raff Hershel , Chadwick Karen J. 
Published: June 2007

SUMMARY1. This study examined the aldosterone response to physiological ACTH infusion (4 ng/kg per min) and pharmacological ACTH injection (1.8 μg) in conscious Long‐Evans rats at 42 h of normoxia (21% O2) or hypoxia (10% O2).2. Hypoxia per se (no exogenous ACTH) significantly decreased control aldosterone levels despite elevated endogenous plasma ACTH).3. Hypoxia attenuated the aldosterone responses to ACTH infusion but not to ACTH injection.4. It was concluded that hypoxia attenuates aldosterone responses to small increases in ACTH, and large increases in ACTH can override this apparent decrease in adrenocortical sensitivity.
EFFECTS OF SUBSTANCE P ON PANCREATIC EXOCRINE SECRETION STIMULATED BY SECRETIN, DOPAMINE AND CHOLECYSTOKININ IN DOGS
Authors: Iwatsuki K. , Yamagishi F. , Chiba S. 
Published: June 2007

SUMMARY1. The effect of substance P (SP) on pancreatic exocrine responses to exogenous cholecystokinin, secretin, and dopamine, were studied in the isolated and blood‐perfused pancreas of dogs.2. Intra‐arterial injection of SP had a significant biphasic effect on pancreatic secretion: an initial transient inhibition, followed by an increase in the secretion stimulated by the infusion of cholecystokinin. However, SP caused only an inhibition of secretion stimulated by the infusion of secretin and dopamine.3. SP increased protein concentration but not bicarbonate concentration in juice stimulated by cholecystokinin, but SP did not affect significantly either protein or bicarbonate concentrations in juice stimulated by secretin and dopamine.4. These results suggest that SP has greater effects on the pancreatic secretion stimulated by cholecystokinin than that stimulated by secretin and dopamine.
ADENOSINE RECEPTORS IN POST‐MORTEM HUMAN CEREBRAL CORTEX AND THE EFFECT OF CARBAMAZEPINE
Authors: Dodd P. R. , Watson W. E. J. , Johnston G. A. R. 
Published: June 2007

SUMMARY1. Representative A1 site‐ and A2 site‐selective ligands for adenosine receptors were found to bind to a single class of non‐co‐operative sites in synaptic membranes prepared from pieces of normal human temporal lobe cerebral cortex obtained at autopsies performed within 24 h post‐mortem.2. The known adenosine antagonists theophylline and 1‐isobutyl‐3‐methylxanthine also bound to these sites and could completely displace either ligand.3. Computer analysis combining data from 21 separate experiments which used membranes prepared from seven different autopsy cases gave the following kinetic parameters for the site: equilibrium dissociation constants (KD) for l‐PIA, 4.1±0.9 nmol/1; KD for NECA, 26±4 nmol/1; KD for theophylline, 28±5 μmol/1; receptor number (Bmax), 510±77 fmol/mg protein.4. Carbamazepine could also displace either radioligand from the sites, although solubility limits for this drug were reached at 50% receptor occupancy. The KD for carbamazepine was 138±18 μmol/1. Other anticonvulsants tested were generally ineffective at their therapeutic concentrations, although phenytoin showed a small amount of ligand binding inhibition.5. The results are in line with earlier studies in rodent tissue preparations, and suggest a possible purinergic component in the anticonvulsant activity of carbamazepine in man.
INFLUENCE OF ALCOHOL AND CAFFEINE CONSUMPTION ON CAFFEINE ELIMINATION
Authors: George J. , Murphy T. , Roberts R. , Cooksley W. G. E. , Halliday J. W. , Powell L. W. 
Published: June 2007

SUMMARY1. Ten healthy male volunteers were each studied on four separate occasions to assess the role of regular caffeine and alcohol intake on caffeine elimination. Antipyrine disappearance was also studied as an established quantitative test of hepatic microsomal function.2. Regular caffeine intake in high doses for 1 week failed to alter either antipyrine or caffeine pharmacokinetics.3. In contrast, alcohol intake of 50 g/day significantly prolonged caffeine half‐life by 72% (P<0.005) and diminished caffeine clearance by 36% (P<0.0005). However, antipyrine kinetics were unaltered.4. These results demonstrate that alcohol, in amounts commonly consumed, is a strong inhibitor of caffeine metabolism.
ETHANOL IMPAIRS BILIARY LYSOSOMAL ENZYME RELEASE IN RATS
Authors: Sewell Richard B. , Grinpukel Susan A. , Yeomans Neville D. 
Published: June 2007

SUMMARY1. The effects of ethanol on hepatic lysosomes are poorly documented. This study examined the biliary release of lysosomal enzymes, a marker of the hepatocyte‐to‐bile excretory pathway, after ethanol administration in the isolated perfused rat liver model.2. At concentrations similar to those reached in human plasma during social drinking, ethanol markedly decreased biliary lysosomal enzyme output and bile flow in the rat. Ethanol did not affect hepatic activities or the release into perfusate of lysosomal and other subcellular marker enzymes.3. Hence, ethanol may potentially inhibit hepatocyte‐to‐bile excretion of other compounds processed through lysosomes.