bluuebunny/crossref_metadata_2025_split huggingface dataset:
NORADRENERGIC REINNERVATION OF THE RAT VAS DEFERENS AFTER VASOVASOSTOMY FOLLOWING VASECTOMY
Authors: DeGaris Richard M. , Pennefather Jocelyn N. 
Published: June 2007

SUMMARY1. Anastomosis (vasovasostomy) of epididymal and prostatic halves of vasa deferentia was carried out in rats in which unilateral or bilateral medial transection (vasectomy) had been performed 4 weeks previously.2. Noradrenaline levels in epididymal halves of vasa deferentia, 8 weeks after anastomosis with prostatic halves, were approximately 40% of those in epididymal halves of contralateral, unoperated vasa deferentia. Catecholamine fluorescence was partially restored after anastomosis.3. Responses of epididymal halves of transected vasa deferentia to electrical field stimulation (1 ms, 60 V, 10 pulses at 0.01–50 Hz) were partially restored 8 and 15 weeks after anastomosis.4. Noradrenaline was equipotent in causing contraction of epididymal halves of unoperated and anastomosed vasa deferentia at 8 and 15 weeks after vasovasostomy. The ability of nisoxetine (0.1 μmol/l) to potentiate the effects of noradrenaline was partially restored by vas deferens repair.5. Noradrenaline levels and neurotransmission in prostatic halves of vasa deferentia were relatively unaffected by vasectomy and subsequent vasovasostomy.6. Fertility was restored 4–8 weeks after bilateral anastomosis performed in a group of eight rats 4 weeks after bilateral vasectomy.7. These observations show that in the rat the noradrenergic denervation of the epididymal segment of the vas deferens after medial transection is partially reversible by anastomosis 4 weeks later, and that full noradrenergic reinnervation of the organ is not essential for the return of fertility after vasectomy and vasovasostomy in this species.
NEUROLOGICAL CONSEQUENCES OF MAGNESIUM DEFICIENCY: CORRELATIONS WITH EPILEPSY
Authors: Leaver D. D. , Parkinson G. B. , Schneider K. M. 
Published: June 2007

SUMMARY1. The plasma calcium and magnesium concentrations of sheep have been manipulated by feeding liquid diets with various calcium and magnesium concentrations.2. When the magnesium status of the diet was low, both plasma calcium and magnesium concentrations declined, but the decline in calcium was much more rapid and extensive when the content of calcium in the diet was also low. This loss of calcium control in magnesium deficiency was attributed to end‐organ resistance to parathyroid hormone.3. Correlation between plasma and CSF calcium and magnesium concentrations indicated that convulsions occurred when CSF magnesium and plasma calcium concentrations declined.4. The neurological mechanisms likely to be responsible for the induction of these convulsions are discussed and the factors precipitating convulsions in magnesium deficiency and epilepsy are compared.
MODULATION OF NORADRENALINE RELEASE IN VIVO THROUGH PREJUNCTIONAL α‐ADRENOCEPTORS
Authors: Majewski H. 
Published: June 2007

SUMMARY1. Extensive in vitro studies have suggested that noradrenaline release from sympathetic nerve endings is modulated by α2‐adrenoceptors on the terminal varicosities, activation of which by α‐adrenoceptor agonists or neuronally released noradrenaline leads to inhibition of transmitter release.2. Studies in intact animals support essentially the physiological operation of this mechanism, whereas human studies have reached mixed conclusions and more information is required.
EXTRACTION OF NEUROTENSIN BY THE LIVER
Authors: Brook Christopher W. , Shulkes Arthur , Sewell Richard B. , Smallwood Richard A. 
Published: June 2007

SUMMARY1. Neurotensin is released from the intestine into the portal circulation and to exert a systemic effect it must traverse the liver intact.2. The role of the liver in neurotensin clearance was examined using the isolated perfused rat liver preparation. Two concentrations of neurotensin were used to determine the extraction capacity of the liver.3. Approximately 10% of the added neurotensin (with either dose) was extracted in a single pass through the liver. This extraction rate was low when compared to previous studies with cholecystokinin (60% extraction in a single pass) and vasoactive intestinal peptide (100%).4. It is concluded that there is a small but high capacity for direct extraction of neurotensin. This low direct extraction percentage supports our previous contention that the major influence of the liver on the metabolism of neurotensin is by the release of neurotensin degrading peptidases into the circulation.
RITANSERIN AND SEROTONERGIC MECHANISMS IN BLOOD PRESSURE AND FLUID REGULATION IN SHEEP
Authors: Nelson M. , Coghlan J. P. , Denton D. A. , Tresham J. J. , Whitworth J. A. , Scoggins B. A. 
Published: June 2007

SUMMARY1. In previous studies, exogenous serotonin (5‐HT), administered intravenously, caused dose‐related increases in mean arterial pressure and heart rate in conscious sheep. The 5‐HT2 antagonist ketanserin (0.1 mg/kg per h, i.v.) was shown to lower blood pressure in the conscious sheep primarily through antagonism of α‐adrenoceptors.2. A newer 5‐HT2 antagonist, ritanserin, is a more selective antagonist in vivo, as it attenuated or abolished pressor responses to exogenous 5‐HT, but not to phenylephrine.3. When infused alone, ritanserin (0.1 mg/kg per h, i.v.) failed to produce a decrease in blood pressure, suggesting that 5‐HT antagonistic properties are not sufficient by themselves to lower blood pressure.4. Ritanserin displayed a different metabolic profile to ketanserin, with a markedly decreased water intake. The mechanism of this effect is unresolved, but may imply a permissive role for 5‐HT in the modulation of drinking responses in the sheep.5. Ritanserin did not modify ACTH‐induced hypertension in sheep.
REPRODUCIBILITY OF PRESSOR RESPONSE TO HANDGRIP: INFLUENCE OF TIME INTERVALS, STRENGTH AND DURATION OF EXERCISE
Authors: Costa F. V. , Borghi C. , Mussi A. , Ambrosioni E. 
Published: June 2007

SUMMARY1. The reproducibility of pressor response to handgrip performed at different time intervals and with different combinations of the product duration × strength of the exercise was evaluated in 14 normotensive subjects recording blood pressure with a non‐invasive automatic device.2. Subjects underwent five consecutive tests (30% of maximal voluntary contraction × 90 s) at 30 min, and 24 h intervals and repeated the test after 12 months. Furthermore, they underwent at 24 h intervals a randomized sequence of handgrip tests whose product strength × duration was combined in order to achieve either a constant or an increasing level of exercise.3. Blood pressure response to exercise performed at 30 min intervals was much less reproducible than that induced by handgrip performed at time intervals ≥ 24 h.4. Increasing gradually the product strength × duration of the handgrip test there was a proportional blood pressure increase, whereas when the product was maintained constant diastolic blood pressure increase was also constant and reproducible within each subject.5. This study shows that it is possible to obtain reproducible diastolic blood pressure responses to handgrip test measuring blood pressure with a non‐invasive automatic device when the tests are performed at a time interval of at least 24 h. The choice of the strength and of the duration of the exercise is very important for the reproducibility of the test.
THE EFFECT OF OXYTOCIN ON PORCINE MALIGNANT HYPERPYREXIA SUSCEPTIBLE SKELETAL MUSCLE
Authors: Sim A. T. R. , White M. D. , Denborough M. A. 
Published: June 2007

SUMMARY1. Certain commercial preparations of oxytocin have been reported to reverse the development of pale soft exudative meat and malignant hyperpyrexia (MH) in pigs in vitro.2. In this study it is shown that preservative‐free oxytocin has no significant effect on the characteristic contractures of MH susceptible (MHS) muscle to halothane, caffeine, succinylcholine and KCl in vitro.3. Whilst a commercial preparation of oxytocin, Syntocinon (containing chlorbutol as preservative), reversed and prevented the MHS characteristic responses, this study demonstrates conclusively that this was entirely due to the preservative chlorbutol.
EFFECTS OF NEUROPEPTIDE Y ON THE PRESSOR RESPONSES TO PHENYLEPHRINE AND TO ACTIVATION OF THE SYMPATHETIC NERVOUS SYSTEM IN ANAESTHETIZED RATS
Authors: Revington Maureen L. , McCloskey D. I. , Potter Erica K. 
Published: June 2007

SUMMARY1. The effects of neuropeptide Y (NPY) on the pressor responses to intravenous injections of phenylephrine and to reflex activation of the sympathetic nervous system by stimulation of the sciatic nerve were examined in anaesthetized rats.2. NPY (10–20 μg/kg) always potentiated the pressor response to exogenous phenylephrine (by a mean of 28.1 ± 5.0%). The effect of the same dose of NPY on the pressor response to sciatic nerve stimulation was variable (sometimes inhibition, sometimes potentiation).3. NPY appears to act by potentiating post‐synaptic a‐adrenoceptor‐mediated vasoconstrictor effects. It may also inhibit noradrenaline release by a presynaptic action. Thus the net effect of NPY on sympathetic activation in vivo may depend on the balance between these two opposing actions.
EFFECTS OF THE OPIOID PEPTIDES [MET5]ENKEPHALIN‐ARG6‐PHE7 AND [MET5]ENKEPHALIN‐ARG6‐GLY7‐LEU8 ON CHOLINERGIC NEUROTRANSMISSION IN THE RABBIT ISOLATED ATRIA
Authors: Wong‐Dusting H. , Rand M. J. 
Published: June 2007

SUMMARY1. The effect of the opioid peptides [Met5]enkephalin‐Arg6‐Phe7 (MEAP) and [Met5]enkephalin‐Arg6‐Gly7‐Leu8 (MEAGL) were compared with those of [Leu5]enkephalin and [d‐Ala2, Met5]enkephalinamide (DAME) on cholinergic neuro‐transmission in the rabbit isolated atria.2. Rabbit isolated atria had a resting rate of 190 beats/min. In the presence of the β‐adrenoceptor antagonist propranolol (0.3 μmol/l), atria responded to electrical field stimulation with a cholinergically mediated negative chronotropic response. The opioid peptides had no effect on the resting rate, but inhibited the negative chronotropic response to field stimulation. The IC50 values for inhibiting the cholinergic responses were 1.4 μmol/l for [Leu5]enkephalin (LE), 1.4 μmol/l for MEAP, 1.3 μmol/l for MEAGL and 0.2 μmol/l for DAME. Responses of a similar magnitude to exogenous acetylcholine were unaffected.3. Thus, MEAP, MEAGL and LE had similar potencies but DAME was about seven times more potent in inhibiting cholinergic neurotransmission in the rabbit isolated atria. The site of inhibition appears to be prejunctional.
HAEMODYNAMIC AND METABOLIC RESPONSES OF LABORATORY RABBITS TO NEAR‐MAXIMAL TREADMILL EXERCISE
Authors: Jover Bernard , McGrath Barry P. , Ludbrook John 
Published: June 2007

SUMMARY1. The haemodynamic and metabolic responses of four laboratory rabbits to horizontal treadmill exercise at 8, 12, 16 and 20 m/min were studied. The primary haemodynamic variables measured were heart rate, cardiac output and arterial pressure. The metabolic variables measured were arteriovenous oxygen difference, whole‐body oxygen consumption and central venous plasma lactate concentration.2. Only at 8 m/min did the haemodynamic and metabolic variables reach an approximate steady state. This was the greatest speed at whichaerobic exercise could be sustained for 4 min in all rabbits.3. As the speed of the treadmill was increased the rabbits showed signs of exhaustion after progressively shorter periods of exercise. Exhaustion was associated with steep rises in central venous plasma lactate concentration. Exhaustion was also usually associated with secondary rises in systemic vascular resistance and arterial pressure, especially at 20 m/min.4. The asymptotic (maximal) values for heart rate, cardiac index and O2 consumption were 386 beats/min, 263 ml/kg per min and 21.7 ml/kg per min, respectively.heart do not permit it to run continuously at other than a slow rate. Exhaustion is associated with increasing oxygen debt and, especially at near‐maximal rates of exercise, with intense vasoconstriction in as yet unidentified vascular beds.
AMITRIPTYLINE ACTION ON SYMPATHETIC NEURONAL FUNCTION IN DEPRESSED WOMEN
Authors: Corona G. L. , Cucchi M. L. , Frattini P. , Santagostino G. , Schinelli S. , Tosca P. , Savoldi F. , Zerbi F. 
Published: June 2007

SUMMARY1. Noradrenaline plasma levels and cardiovascular function modifications with orthostatic challenge during therapy were studied in 59 female depressed inpatients treated with 100 mg amitriptyline daily by intramuscular route for 4 weeks.2. Therapy induced an increase in pulse rate in supine and upright positions, a decrease of noradrenaline levels and modified standing systolic and (partially) diastolic blood pressure, particularly in elderly subjects.3. No correlation between neurotransmitter or functional changes and drug plasma levels was noted.4. The supposed lower noradrenergic output together with blood pressure drop in both positions suggests a reduced sympathetic tone.
POTASSIUM CONTRACTURES IN THE MOUSE DIAPHRAGM: REGIONAL VARIATION IN THE MULTIPHASIC RESPONSE
Authors: Singh Yadhu N. , Dryden William F. 
Published: June 2007

SUMMARY1. Submaximal potassium‐induced contractures were studied in isolated mouse hemidiaphragms (HD) and compared with extensor digitorum longus (EDL) and soleus.2. In the HD, the contracture was triphasic: an initial small, fast phase followed by a larger slow phase, and a late phase which was seen on prolonged exposure.3. Costal segments of the HD responded to elevated potassium with a larger fast phase, while dorsal or ventral segments produced a larger slow phase.4. In calcium‐free solution, the fast phase appeared to be unaffected, while the slow phase was potentiated and its time course abbreviated. The late phase was greatly attenuated or abolished.5. In the soleus, but not the EDL muscle, contracture amplitude in calcium‐free solution was potentiated and the time course was shortened.6. The characteristics of potassium‐induced contractures of both the soleus and EDL muscles are to be seen in the response of the hemidiaphragm, but there is a regional variation in their proportional contribution which suggests a heterogeneity in diaphragm composition.
THE EFFECT OF SMOKING ON CAFFEINE ELIMINATION: IMPLICATIONS FOR ITS USE AS A SEMIQUANTITATIVE TEST OF LIVER FUNCTION
Authors: Murphy Therese L. , McIvor Carolyn , Yap A. , Cooksley W. G. E. , Halliday June W. , Powell L. W. 
Published: June 2007

SUMMARY1. The effects of caffeine ingestion and cigarette smoking on caffeine and antipyrine pharmacokinetics were studied using normal subjects as their own controls before and after cessation of smoking in an attempt to minimize genetic and other environmental influences.2. Moderate caffeine ingestion had no inducing effect on caffeine or antipyrine clearance.3. Cessation of cigarette smoking significantly reduced clearance of caffeine and antipyrine.4. These results demonstrate that cigarette smoking significantly affects caffeine pharmacokinetics and this may contribute to the variable results for caffeine kinetics found in patients with liver disease.
DISTRIBUTION OF CADMIUM IN BODY ORGANS AND HEPATIC METALLOTHIONEIN CONTENT FOLLOWING CHELATION THERAPY
Authors: Tewari Prakash C. , Flora Swaran J. S. , Tandon Sushil K. 
Published: June 2007

SUMMARY1. Calcium trisodium diethylene triamine penta‐acetate (CaNa3DTPA), sodium 1,2 diaminocyclohexane tetra‐acetate (Na2CDTA), triethylenetetramine hydrochloride (TETA. HCl) and sodium diethyldithiocarbamate (NaDDC) were investigated for their efficacy to mobilize cadmium (Cd) from various tissues and hepatic metallothionein (MT) in Cd‐exposed rats.2. All chelating agents reduced the hepatic Cd burden but did not elicit any influence on other tissues, except that TETA. HCl lowered pancreas Cd and NaDDC increased brain Cd.3. Cadmium‐induced hepatic MT was lowered upon treatment with CaNa3DTPA while it increased further following treatment with NaDDC.4. The chelating agents, in split doses, are capable of reducing the hepatic burden of Cd and altering the hepatic MT level.5. While all the chelating agents decreased Cu content of hepatic MT, only CaNa3DTPA decreased its Zn content and TETA. HCl mobilized MT‐bound Cd.6. The administration of chelating agents alone in normal animals showed that NaDDC induced greater hepatic MT synthesis and increased MT‐bound Zn than other chelating agents.
DISPOSITION OF PHENYTOIN AND PHENOBARBITONE IN THE ISOLATED PERFUSED HUMAN PLACENTA
Authors: Kluck R. M. , Cannell G. R. , Hooper W. D. , Eadie M. J. , Dickinson R. G. 
Published: June 2007

b1. The disposition of the anti‐epileptic agents phenytoin (PHT) and pheno‐barbitone (PB) was investigated in lobules of term human placentae perfused using separate maternal and fetal circulations for 6 h periods.2. No evidence for metabolism of PHT or PB to their p‐hydroxylated or other derivatives was found either in perfused lobules or by incubation with placental microsomes.3. Both PHT and PB were readily transferred across the placenta after administration to either the maternal or fetal perfusates.4. PHT, unlike PB, showed considerable accumulation in placental tissue.
MINERALOCORTICOIDS ARE NOT INVOLVED IN THE ANTIHYPERTENSIVE EFFECT OF NEONATAL THYMECTOMY IN THE GENETICALLY HYPERTENSIVE LH RAT
Authors: Bataillard Alain , Gomez‐Sanchez Celso E. , Vincent Madeleine , Touraine Jean‐Louis , Sassard Jean 
Published: June 2007

SUMMARY1. In order to determine whether the antihypertensive effect of neonatal thymectomy in genetically hypertensive rats could be mediated through altered adrenal function, systolic blood pressure (SBP) and urinary excretion of deoxycorticosterone (DOC), corticosterone (B) and aldosterone were measured in thymectomized hypertensive (LH), normotensive (LN) and low‐blood pressure (LL) rats of the Lyon strain. Sham‐operated animals served as controls.2. Neonatal thymectomy prevented the spontaneous increase of SBP in LH rats while it slightly decreased the SBP of LN and did not change that of LL rats.3. Five week old sham‐operated LH rats exhibited an increased urinary excretion of DOC and a decreased excretion of B compared with both LN and LL controls. Thymectomy did not alter the urinary excretion of adrenal steroids in LN and LL rats. The urinary excretion of B was markedly enhanced in thymectomized LH rats whereas that of DOC remained unmodified.4. These data suggested that the thymus could be involved in the development of hypertension in LH rats.5. The antihypertensive effect of thymectomy did not seem to be mediated by a decreased mineralocorticoid production in the genetically hypertensive rat of the Lyon strain.
OXIDATION PHENOTYPING IN CHINESE AND MALAY POPULATIONS
Authors: Lee Edmund J.D. , Nam Yeoh Peng , Hee Gong Ngie 
Published: June 2007

SUMMARY1. Debrisoquine hydroxylation phenotyping was carried out in 97 Chinese and 97 Malay healthy volunteers.2. No poor metabolizer was found in the Chinese population. Using a metabolic ratio antimode of 10.0, two poor metabolizers were present amongst the Malays studied.
CAFFEINE‐AND POTASSIUM‐INDUCED CONTRACTURES OF MOUSE ISOLATED SOLEUS MUSCLE: EFFECTS OF VERAPAMIL, MANGANESE, EGTA AND CALCIUM WITHDRAWAL
Authors: Savage A. O. , Atanga K. G. 
Published: June 2007

SUMMARY1. The effects of verapamil, manganese, EGTA and Ca2+‐withdrawal on caffeine and potassium‐induced contractures of the mouse isolated soleus muscle have been studied. All four treatments profoundly inhibited, in concentration‐dependent manner, both K+‐and caffeine‐induced contractures, and recovery from these treatments was slight.2. Caffeine (5.14–51.4 mmol/1), elicited biphasic contractures, characterized by an initial phasic, and subsequent tonic contractures. K+‐induced contractures were monophasic except at the higher concentrations (53.4–214 mmol/1), when biphasic responses were also recorded. The biphasic K+ contracture had a time course similar to the caffeine‐induced response.3. Both phases of the caffeine and K+ responses were abolished by the introduction of CA2+‐free Krebs'‐Henseleit solution (KHS). Increasing [Ca2+]o from 1 to 5 mmol/1, markedly inhibited the amplitude of caffeine and K+ contractures.4. In high [K+]o KHS, peak contractures to caffeine were reduced to about 50% of those in normal KHS. In the presence of 15.4 mmol/1 caffeine, the responses to lower concentrations of K+ (13.4–26.8 mmol/1) increased, while responses evoked by the higher K+ concentrations were depressed compared with controls in normal KHS.5. Pancuronium or d‐tubocurarine severely inhibited caffeine‐induced contractures, but only slightly inhibited K+‐induced responses.6. It is suggested that both caffeine‐and K+‐induced contractures of the mouse soleus are dependent upon the presence of [CA2+]o, and that these contractures possibly occurred as a result of extracellular Ca2+‐influx.
EFFECT OF ANTIHYPERTENSIVE THERAPY ON THE CARDIOVASCULAR AMPLIFIERS
Authors: Korner P. I. , Adams M. A. , Jennings G. L. , Bobik A. 
Published: June 2007

SUMMARY1. In established chronic hypertension the amplifier properties of vessels and heart contribute about 70% to the maintenance of the elevated blood pressure (BP). Recent studies in spontaneously hypertensive rats (SHR) suggest that the structural changes occur very early and their amplifier properties may be critical for the development of hypertension.2. In patients with primary hypertension, the greater the regression of cardiac and vascular hypertrophy, the slower the subsequent redevelopment of hypertension. Following regression of hypertrophy, the antihypertensive action of moderate regular exercise can maintain BP in the normal range in a proportion of patients.3. Early treatment of SHR with enalapril greatly reduces the subsequent ‘steady‐state’ BP in SHR. This produces virtually complete regression of vascular hypertrophy, but somewhat lesser degrees of regression of cardiac hypertrophy.4. These studies serve as models for primary and secondary prevention of hypertension. A strategy based on intermittent drug and non‐pharmacological therapy in man may contribute to the secondary prevention of atherosclerosis, in view of the adverse effects on lipid profiles of many antihypertensive drugs.
EFFECTS OF ANTIHYPERTENSIVE DRUGS ON CARDIOVASCULAR RISK FACTORS
Authors: Howes L. G. , Louis W. J. 
Published: June 2007

SUMMARY1. Large scale studies have failed to show a substantial benefit of antihypertensive therapy on the incidence of ischaemic heart disease.2. This may be due to adverse effects of antihypertensive drugs on plasma lipoproteins or because of failure to adequately manage other risk factors for atherogenesis.3. Hypercholesterolaemia is very common in patients receiving antihypertensive therapy, and is difficult to manage successfully using existing treatment strategies.4. The achievement of a reduction in mortality and morbidity from ischaemic heart disease amongst hypertensive patients represents a major challenge. Success will probably depend upon the development of adequate methods of lowering plasma cholesterol levels.
AN UNUSUAL PHOSPHATIDYLINOSITOL TURNOVER PATHWAY IN NORADRENALINE‐PERFUSED RAT HEARTS
Authors: Woodcock Elizabeth A. , Smith A. Ian , Wallace Catherine A. , White L. Barbara Schmauk 
Published: June 2007

SUMMARY1. The phosphatidylinositol turnover pathway has been studied in noradrenaline‐perfused rat hearts using anion‐exchange high performance liquid chromatography.2. The active calcium‐releasing compound inositol‐(1,4,5)trisphosphate was detected together with its degradation products inositol‐(1,4)bisphosphate and inositol monophosphate. All these products increased in response to noradrenaline stimulation.3. At noradrenaline perfusion times from 5 s to 20 min there was no appearance of inositol‐(1,3,4,5)tetrakisphosphate or its degradation products: inositol‐(1,3,4)trisphosphate or inositol‐(1,3) and (3,4)bisphosphates.4. These data suggest the absence of the inositol‐(1,4,5)trisphosphate phosphorylation/dephosphorylation pathway in heart.