bluuebunny/crossref_metadata_2025_split huggingface dataset:
TRAIN‐OF‐FOUR FADE DURING NEUROMUSCULAR BLOCKADE INDUCED BY TUBOCURARINE, SUCCINYLCHOLINE OR α‐BUNGAROTOXIN IN THE RAT ISOLATED HEMIDIAPHRAGM
Authors: Cheah L. S. , Gwee M. C. E. 
Published: June 2007

SUMMARY1. Nerve‐evoked maximal twitches (T1, T2, T3, T4) of the rat isolated hemidiaphragm to train‐of‐four (TOF) stimulation (2 Hz2 s) were recorded continuously in the absence or presence of tubocurarine (1.5 μmol/1), succinylcholine (40 μmol/1) or α‐bungarotoxin (1 μmol/1). The T1 and T4 response‐time profiles for the three drugs were analysed with respect to amplitude depression and the TOF ratio (T4/T1) during the development of and recovery from neuromuscular blockade.2. Tubocurarine produced T1 block accompanied by intense TOF fade; for the same degree of T1 block, the TOF ratio was lower during the recovery from blockade after washing out tubocurarine from the bath than during the onset of blockade. There was also a correspondingly slower recovery of the TOF ratio from 90% T1 block to control levels when compared with the time for complete T1 recovery. Fade and twitch tension depression were shown clearly to be separate responses, each with its own response‐time profile. Fade is therefore not simply a consequence of postjunctional cholinoceptor blockade.3. Succinylcholine produced T1 block with only moderate TOF fade; similar recovery rates from 90% T1 block to control levels were obtained for T1 and the TOF ratio.4. α‐Bungarotoxin produced irreversible and complete neuromuscular blockade during which TOF fade was virtually absent.5. The results obtained in this study closely resemble those from other similar studies in animals and in humans and clearly demonstrate that the rat isolated hemidiaphragm is a suitable in vitro model for time course studies on TOF fade.
RISK‐BENEFIT OF SPECIFIC ANTIHYPERTENSIVE REGIMENS: RELEVANCE OF METABOLIC AND HAEMODYNAMIC EFFECTS OF α1‐BLOCKERS
Authors: Reid John L. , Curzio Joan , Elliott Henry L. 
Published: June 2007

SUMMARY1. Existing strategies for the control of high blood pressure have had a disappointing impact on coronary heart disease—the major cause of death in hypertension.2. There is a need for more work to identify the relationship between blood pressure, atheroma and other risk factors.3. A more aggressive approach to treatment may be indicated, especially in high risk groups.4. In addition to treatment of blood pressure, other major risk factors (lipids and smoking) must be tackled.5. Alternative treatment regimens with different mechanisms of action and/or effects on lipids should be evaluated in practice.6. Selective α1‐blockers have potential haemodynamic advantages, improve the lipid profile and are well tolerated as first or second line therapy.
CHANGE IN BLOOD PRESSURE IN RELATION TO CHANGE IN NUTRIENTS EFFECTED BY MANIPULATION OF DIETARY SODIUM AND POTASSIUM
Authors: Nowson C. A. , Morgan T. O. 
Published: June 2007

SUMMARY1. As part of a study investigating the effect of dietary alterations of sodium and potassium intake on blood pressure, the changes in nutrients that occurred with dietary intervention were determined.2. Mild hypertensive subjects were randomized to one of four dietary intervention groups: control; high potassium; low sodium; low sodium, high potassium. The changes in nutrients in each diet group were assessed by dietary history and five repeat 24 h dietary recalls. Assessment was validated by measurement of urinary nitrogen excretion and urinary electrolytes.3. The three dietary intervention groups experienced a fall in blood pressure (systolic: 4.4 ± 1.0 mmHg, P<0.005; diastolic: 3.3 ± 0.7 mmHg, P<0.001), greater than that observed in the control group.4. The only significant dietary change across all diet groups was a reduction in the dietary sodium/potassium ratio, which was significantly less than that of the control group. The only other nutrient to differ from the control in all groups was fat intake, which was reduced.5. In the control group there was a small but significant decrease in energy, fibre, protein, carbohydrate, potassium and magnesium intake. In the high potassium group there was a significant increase in fibre, carbohydrate, potassium, magnesium, and a decrease in calcium intake. In the low sodium group there was a decrease in energy intake with a subsequent reduction in all nutrients except alcohol. In the low sodium, high potassium group there was a significant reduction in dietary sodium and protein and an increase in fibre, carbohydrate, potassium and magnesium.6. The reduction of the dietary sodium/potassium ratio correlated with a reduction in the urinary sodium/potassium ratio. This was the best predictor for change in diastolic pressure in all groups, suggesting that reduction in the sodium/potassium ratio contributed to the fall in blood pressure.7. Reduction of sodium intake and increase in potassium intake by dietary means caused a reduction in blood pressure which does not appear to be due to alteration of other measured dietary constituents.
DECREASED RENAL RESPONSES TO ATRIAL NATRIURETIC PEPTIDE IN RENAL WRAP HYPERTENSION
Authors: Takata M. , Denton K. M. , Woods R. L. , Anderson W. P. 
Published: June 2007

SUMMARY1. The effects of atrial natriuretic polypeptide (ANP) on renal function were examined in renal wrap hypertensive rabbits and sham operated rabbits.2. ANP (2μg/min) induced hypotension, but did not produce significant diuresis, natriuresis or change in the glomerular filtration rate (GFR) in renal wrap hypertensive rabbits (n= 8).3. In sham operated normotensive rabbits (n= 4), ANP induced significant diuresis (230%) and increased GFR by about 40%.4. Thus, ANP was markedly less effective in the impaired kidneys of renal wrapped rabbits than in normal kidneys.
THE EFFECT OF EPANOLOL ON INTRA‐ARTERIAL AMBULATORY BLOOD PRESSURE AND BARORECEPTOR HEART RATE REFLEX IN ESSENTIAL HYPERTENSION
Authors: Smith Stephen A. , Littler William A. 
Published: June 2007

SUMMARY1. The effect of chronic treatment with epanolol, a new cardioselective P‐adrenoceptor antagonist with moderate pi‐selective intrinsic sympathomimetic activity (ISA), on 24 h ambulatory intra‐arterial blood pressure (24 h IABP) and the sino‐aortic baroreceptor heart rate (SAB/HR) reflex was investigated in six hypertensive subjects.2. All subjects demonstrated a >10% reduction in mean arterial pressure with atenolol therapy (100 mg once daily) before entering a randomized, double‐blind, placebo‐controlled, crossover protocol with epanolol (100 mg twice daily for 4 weeks).3. Epanolol treatment at this dose was not associated with significant reduction in systolic or diastolic 24 h IABP or heart rate. There was no change in SAB/HR reflex set point, sensitivity or latency with epanolol.4. β1‐selective ISA may be undesirable in β‐adrenoceptor antagonists used to treat hypertension.
EFFECT OF LABETALOL ON HUMAN PLATELET FUNCTION
Authors: Anfossi Giovanni , Trovati Mariella , Lanzio Mario , Mularoni Elena , Massucco Paola , Emanuelli Giorgio 
Published: June 2007

SUMMARY1. The effects of the α‐β‐adrenergic antagonist labetalol on the activation of human platelets by adrenaline and other aggregating stimuli have been investigated.2. Labetalol inhibited platelet aggregation and secretion induced by collagen and the second phase of aggregation caused by ADP, platelet activating factor, adrenaline and ionophore A23187. Adrenaline‐induced platelet activation was inhibited by the lowest labetalol concentration. The response to Na arachidonate was minimally affected and the arachidonate‐induced thromboxane B2 generation was only partially prevented.3. The pre‐incubation with low concentration of ionophore A23187 overcame labetalol's inhibition of collagen‐induced platelet aggregation.4. Labetalol did not influence intraplatelet cyclic AMP levels.5. The present investigation provided evidences that the modulation of human platelet function by labetalol could be related also to a decreased Ca2+ availability.
BUPIVACAINE ACUTE TOXICITY PROTECTION BY DIAZEPAM IN MICE
Authors: Bruguerolle B. , Emperaire N. , Ottomani A. , Manelli J. C. 
Published: June 2007

SUMMARY1. The effects of acute and 8‐day administration of diazepam (DZP) on the acute toxicity of bupivacaine in the mouse were studied.2. Protection of bupivacaine‐induced acute toxicity by DZP appears to be dose‐dependent after treatment for 8 days but not after acute treatment.
THE INTERRELATIONSHIP OF MORPHINE AND THE PARASYMPATHETIC NERVOUS SYSTEM IN DIGOXIN‐INDUCED ARRHYTHMIAS IN THE GUINEA‐PIG
Authors: Rabkin Simon W. 
Published: June 2007

SUMMARY1. The role of the parasympathetic nervous system and the effect of morphine on cardiac arrhythmias induced by digitalis was assessed in guinea‐pigs that had digitalis arrhythmias produced by digoxin 50 μg/kg intravenously plus 500 μg/kg per h.2. Morphine produced a dose‐dependent rightward shift in the relationship between digoxin dose and arrhythmias. Morphine 5 mg/kg subcutaneously (s.q.) was associated with significantly (P < 0.05) higher digoxin doses both at the onset of ventricular arrhythmias and at development of fatal arrhythmias compared with the control group that received saline s.q.3. Vagotomy and atropine prevented the effect of morphine so that the dose‐response relationships and the mean digoxin dose at onset of ventricular arrhythmias and the development of fatal arrhythmias were not significantly different from the control group receiving saline.4. These data indicate that morphine limits the development of digitalis arrhythmias and this effect is, at least in part, mediated through the parasympathetic nervous system.
SIMULATION OF ACUTE HAEMORRHAGE IN UNANAESTHETIZED RABBITS
Authors: Ludbrook John , Potocnik Simon J. , Woods Robyn L. 
Published: June 2007

SUMMARY1. We have shown that it is feasible to match the linear rate of fall of cardiac output that occurs during haemorrhage at 2.7 ml/kg per min in unanaesthetized rabbits by constricting the thoracic inferior vena cava so as to decrease venous return.2. The changes in systemic vascular resistance, arterial pressure and heart rate that occurred during haemorrhage were mimicked by simulated haemorrhage. They were reproducible when simulated haemorrhage was performed three times at 90 min intervals, and when it was repeated four times over 12 days.3. Simulated haemorrhage caused rises in plasma renin activity (PRA) and plasma arginine vasopressin concentration (AVP) that were similar to those reported after haemorrhage. The response of PRA was unaffected by repeated simulated haemorrhage, but the response of AVP was less on the third occasion.4. When the shed blood was re‐infused after haemorrhage, cardiac output tended to remain low and systemic vascular resistance high. After simulated haemorrhage, all haemodynamic variables returned to normal within 2 min of releasing the caval cuff.5. Haematocrit fell during haemorrhage, and remained low for at least 5 days after replacement of the shed blood. Haematocrit was unaffected by simulated haemorrhage.6. Venous pressure below the inflatable cuff rose by 6 mmHg in the course of simulated haemorrhage.7. We conclude that the central haemodynamic effects of haemorrhage can be closely and repeatedly simulated by inflating a cuff on the inferior vena cava. This provides a useful technique for repeatedly studying the effects of acute reduction of central blood volume in conscious animals.
INTERACTION BETWEEN ATRIAL NATRIURETIC FACTOR AND OUABAIN: VASCULAR REACTIVITY TO NORADRENALINE IN PENTOBARBITAL ANAESTHETIZED DOGS
Authors: Chintala Madhu S. , Jandhyala Bhagavan S. 
Published: June 2007

SUMMARY1. The influence of intra‐arterial infusion of rat atrial natriuretic factor (ANF 8–33) and/or ouabain on the vascular responses to noradrenaline was investigated in the denervated and flow‐controlled hindlimb preparations in pentobarbital anaesthetized dogs.2. During the continuous infusions of ANF (30–40 min) vascular responses to noradrenaline were significantly depressed. Subsequent infusion of ouabain together with ANF (50–60 min) reversed and restored the vascular reactivity to the control levels. Hypotension produced by ANF infusion was partially reversed during the simultaneous infusions of both the agents.3. In a separate series of experiments, in which ouabain was first infused (50–60 min) vascular responses to noradrenaline were significantly enhanced. Subsequent infusions of ANF (plus ouabain) even up to 60 min or longer failed to alter the enhanced vascular responsiveness facilitated by ouabain.4. The present studies demonstrate a physiological antagonism between ANF and ouabain and such a phenomenon could account for the previous observation that vascular reactivity to noradrenaline was progressively enhanced after acute blood volume expansion. Whereas plasma levels of both ANF and ouabain‐like inhibitor(s) of the sodium pump are elevated after volume expansion, inhibitory effects of ANF on the vascular smooth muscle may be compromised in the presence of an Na+ pump inhibitor(s).
NEUROCHEMISTRY OF THE SYMPATHETIC INNERVATION TO THE UTERUS
Authors: Bell C. , Malcolm S. J. 
Published: June 2007

SUMMARY1. The uterus is supplied by numerous noradrenergic sympathetic nerve fibres, which supply the intramural vasculature and also, in some species at least, the myometrium.2. Pregnancy is associated with progressive loss of catecholamine from these nerves. Although some direct mechanical damage due to stretching of the uterine wall contributes to this effect, it is primarily due to hormonal influences.3. In animal experiments, the changes in uterine catecholamine occurring during pregnancy are mimicked by intra‐uterine administration of progesterone.4. The action of progesterone appears not to be selective for pelvic sympathetic neurons, or those in which transmitter turnover rate is particularly slow. The mechanism of depletion is probably through inhibition of tyrosine hydroxylase activity.5. The functional role of this phenomenon during pregnancy, if one exists, seems likely to be related to protection of the fetoplacental blood supply against sympathetically mediated vasospasm. It is also possible that circulating progesterone may have a general inhibitory action on the female sympathetic nervous system.
CATECHOLAMINE INACTIVATION IN UTERINE TISSUES: CHANGES IN PREGNANCY IN THE RAT
Authors: Kennedy J. A. , de la Lande I. S. 
Published: June 2007

SUMMARY1. In vitro metabolism of [3H]‐(—)‐noradrenaline (3H‐NA), 0.2 μmol/l, was measured in rat endometrial and myometrial slices at different stages of gestation and compared with that in dioestrous rats. Metabolism of 3H‐NA, 0.2 μmol/l, was measured in rat placental slices from day 14 of gestation onwards.2. 3H‐NA was metabolized mainly by deamination in rat myometrium, with [3H]‐3,4‐dihydroxyphenylethylene glycol, (3H‐DOPEG) being the major metabolite. Cocaine, 30 μmol/l, inhibited 3H‐DOPEG formation and the amount of 3H‐NA remaining in the tissue. O‐methylated metabolite formation was unaffected by cocaine.3. O‐methylation and deamination were equally active pathways for metabolizing 3H‐NA in rat endometrium. O‐methylation to [3H]‐normetanephrine (3H‐NMN) predominated in the placenta. In both tissues O‐methylated metabolite formation was inhibited by 30 μmol/l cocaine.4. In myometrium, metabolite formation per gram was constant in the first half of pregnancy and was similar to that in dioestrous animals. By day 17 of gestation, however, [3H]‐O‐methylated deaminated metabolites (3H‐OMDA), comprising 3‐methoxy, 4‐hydroxy‐phenylethylene glycol and vanillylmandelic acid, and 3H‐NMN formation were less than in dioestrous animals.5. Endometrial 3H‐NMN and 3H‐DOPEG formation per gram were higher in rats at day 5 of gestation than in dioestrous rats but metabolite formation per gram declined thereafter to reach values equal to (3H‐DOPEG) or less than (3H‐OMDA and 3H‐NMN) those in dioestrous rats.6. 3H‐NMN and 3H‐OMDA formation per gram decreased from day 14 to day 20 of gestation in rat placentae.7. The lack of evidence for increased O‐methylation of noradrenaline in rat endometrium or myometrium in late pregnancy contrasts with previous reports of increased catechol‐O‐methyltransferase activity in the pregnant rat uterus.
ENZYME INDUCTION BY EATING CHARCOAL‐GRILLED STEAK WITH NO EFFECT ON BLOOD LIPIDS
Authors: Heller R. F. , Henry D. A. , Brent P. J. 
Published: June 2007

SUMMARY1. There has been interest in the suggestion that enzyme‐inducing drugs, such as anticonvulsants, may produce beneficial changes in lipoprotein levels, in particular a rise in the ratio of high density lipoprotein cholesterol to total cholesterol.2. This controlled study observed the effects of diets of charcoal or oven‐cooked beef on antipyrine clearance (a commonly used measure of drug metabolizing capacity), the apparent oral clearance of phenacetin (a measure of cytochrome P448‐dependent enzyme activity) and blood lipids in 18 healthy volunteers.3. Charcoal‐cooked beef increased antipyrine clearance by an average of 20% (P < 0.059) and increased the apparent oral clearance of phenacetin fivefold (P < 0.01). In contrast, oven‐cooked beef did not significantly alter either measure of microsomal function. Neither diet had any effects on blood lipids.4. We conclude that the type and degree of enzyme induction achieved by this type of dietary manipulation does not produce beneficial changes in lipoprotein profiles. A previously noted rise in high density lipoprotein cholesterol levels in volunteers fed charcoal‐cooked beef may have been due to the effects of charcoal formed by charring of the beef during cooking.
EFFECT OF DILTIAZEM, VERAPAMIL AND DANTROLENE ON THE CONTRACTILITY OF ISOLATED MALIGNANT HYPERPYREXIA‐SUSCEPTIBLE HUMAN SKELETAL MUSCLE
Authors: Foster P. S. , Hopkinson K. C. , Denborough M. A. 
Published: June 2007

SUMMARY1. Diltiazem (10 μmol/L) and verapamil (10 μmol/L) inhibited the hypercontractility induced by 3% halothane and 2 mmol/L caffeine in malignant hyperpyrexia susceptible (MHS) muscle. Diltiazem also inhibited 80 mmol/L KCl contractures.2. Like the skeletal muscle relaxant dantrolene sodium (6 μmol/L), diltiazem not only prevented but reversed the abnormal contractures induced by halothane and caffeine.3. The effect on caffeine contractures of diltiazem and dantrolene in combination was additive.4. The ability of diltiazem and verapamil to inhibit the hypercontractility of MHS muscle suggests that Ca2+ influx across the transverse tubular membrane may be important in the aetiology of the malignant hyperpyrexia syndrome.5. These results also suggest an abnormality in transverse tubule—sarcoplasmic reticulum communication.
EFFECTS OF SUBACUTE OPIOID ADMINISTRATION DURING LATE PREGNANCY IN THE RAT ON THE INITIATION, DURATION AND OUTCOME OF PARTURITION AND MATERNAL LEVELS OF OXYTOCIN AND ARGININE VASOPRESSIN
Authors: Evans R. G. , Olley J. E. , Rice G. E. , Abrahams J. M. 
Published: June 2007

SUMMARY1. The effects, on parturition in the rat, of subacute and acute opioid administration were studied. Further experiments investigated the role of modulation of maternal plasma and pituitary oxytocin (OXY) and arginine vasopressin (AVP) levels in these effects.2. Subacute opioid (M320, buaprenorphine or bremazocine) administration prolonged the gestation of rats. This was accompanied by toxic effects on the offspring. Acute subcutaneous (s.c.) M320 (10 μg/kg) administration was accompanied by prolonged gestation without toxic effects.3. Subacute M320 (10 μg/kg, s.c., twice daily) treatment was accompanied by increased interbirth intervals in parturient rats.4. Maternal OXY but not AVP release, as assessed by measurement of plasma and pituitary immunoreactivity, was elevated during and up to 1 h after the completion of parturition. Subacute M320 treatment did not inhibit this elevated OXY release.
DIGOXIN ENHANCES THE PRESSOR RESPONSE TO ALDOSTERONE ADMINISTRATION IN CONSCIOUS SHEEP
Authors: Spence Campbell D. , Coghlan John P. , Whitworth Judith A. , Scoggins Bruce A. 
Published: June 2007

SUMMARY1. This study examined the hypothesis that inhibition of Na, K ATPase with digoxin would enhance the pressor response to aldosterone infusion in conscious sheep.2. While intravenous infusion of digoxin (10 μg/kg per day for 5 days) had no effect on blood pressure and aldosterone infusion (6 μg/kg per day for 5 days) increased blood pressure by 7 mmHg, combined infusion of digoxin and aldosterone increased blood pressure by 17 mmHg.3. The metabolic effects of the combined digoxin and aldosterone infusion were similar to those for aldosterone alone, suggesting that digoxin did not enhance the mineralocorticoid action of aldosterone.4. The results of this study suggest that changes in Na influx (aldosterone‐dependent) and efflux (digoxin‐dependent) are important in the genesis of aldosterone‐induced hypertension.
EFFECTS OF ALTITUDE ON ATRIAL NATRIURETIC PEPTIDE: THE BICENTENNIAL MOUNT EVEREST EXPEDITION
Authors: Tunny Terry J. , van Gelder James , Gordon Richard D. , Klemm Shelley A. , Hamlet Stephen M. , Finn Wendy L. , Carney Gavin M. , Brand‐Maher Carol 
Published: June 2007

SUMMARY1. Overnight recumbent atrial natriuretic peptide levels were significantly elevated in all ten subjects of the Australian Bicentennial Mount Everest Expedition during the first week at 5400 m, during acclimatization.2. Twenty‐four hour urine volume and urine sodium increased markedly at altitude.3. Plasma renin activity and plasma aldosterone levels decreased significantly at altitude.4. No significant changes in plasma cortisol, plasma sodium or potassium, body temperature, systolic or diastolic blood pressure or heart rate were observed.5. Although it was impossible to control or measure salt and water intake during the study, results suggest that atrial natriuretic peptide may be important in the reduction in renin and aldosterone levels and in the diuresis and natriuresis necessary to adapt to hypoxia at altitude.
MOUSE ASTROCYTES POSSESS SPECIFIC ANP RECEPTORS WHICH ARE LINKED TO cGMP PRODUCTION
Authors: Teoh R. , Kum W. , Cockram C. S. , Young J. D. , Nicholls M. G. 
Published: June 2007

SUMMARY1. Receptors for atrial natriuretic peptide (ANP) have been identified on mouse astrocytes in primary culture, and have similar characteristics to those found on previously recognized ANP‐target tissues.2. Scatchard analysis revealed one class of high affinity receptors with a Kd of 0.32 nmol/L. The IC50 for specific binding was 0.5 nmol/L.3. Ligand binding resulted in stimulation of guanylate cyclase.4. Under reducing conditions, the covalently cross‐linked receptor‐ANP complex migrated on SDS‐polyacrylamide gels as a single band with an apparent molecular weight of 66 kDa.5. Although the physiological relevance of our observations remains to be determined, these data document that cultured mouse astrocytes contain specific high‐affinity ANP receptors which are linked to the production of cGMP.