bluuebunny/crossref_metadata_2025_split huggingface dataset:
MECHANISMS FOR REGULATION OF ARTERIAL TONE BY Ca2+‐ DEPENDENT K+ CHANNELS IN HYPERTENSION
Authors: Rusch Nancy J. , Liu Yanping , Pleyte Kay A. 
Published: June 2007

SUMMARY1. The membrane potential and reactivity of arterial smooth muscle cells is regulated by a variety of K+ channels, which are highly expressed in vascular smooth muscle meuscle membrances.2. Of these K+ channel types, the high‐conductance, Ca2+‐ependent K+ channel appears to be up‐regulated in arterial smooth muscle membrances from hypertensive animals.3. Patch‐clamp studies show that whole‐cell membrances and membrane patches of arterial smooth muscle obtained from rats with genetic or renal hypertension show an increased macroscopic and single‐channel Ca2+‐activated K+ current. Pharmacological block of this K+ current profoundly constricts aortic, renal, mesenteric and femoral arteries obtained from the same hypertensive animals, suggesting that Ca2+‐dependent K+ current is a critical determinant of resting membrane potential in arterial muscle exposed to elevated blood pressure.4. Thus, K+ efflux through Ca2+‐dependent K+ channels appears to constitute an important homeostatic mechanism for buffering increases in arterial reactivity in hypertension.
POTASSIUM CHANNELS AND THE CORONARY CIRCULATION
Authors: Dellsperger Kevin C. 
Published: June 2007

SUMMARY1. Mechanisms responsible for the regulation of coronary blood flow during physiologically important situations, such as reactive hyperamia, hypoxia, ischeaemia, coronary artery occlusion and increased metabolic demand, have eluded the scientific community.2. As knowledge regarding potassium channel physiology and biophysics has expanded, the potential role of these channels in regulating coronary blood flow has been studied.3. Recent data have demonstrated that ATP‐sensitive potassium channels (K+[ATP]) play an important role in maintaining basal coronary blood flow, contribute to the regulation of coronary blood flow during hypoxia, acidosis, ischaemia, reactive hyperaemia and ischaemic preconditioning. The role of potassium channels in the regulation of coronary blood flow during increases in metabolic stimulation is controversial.4. Thus, potassium channels, particularly K+[ATP], appear to play an important role in regulating coronary blood flow during physiologically important stimuli.
ELECTRICAL STIMULATION OF THE AUDITORY NERVE: THE CODING OF FREQUENCY, THE PERCEPTION OF PITCH AND THE DEVELOPMENT OF COCHLEAR IMPLANT SPEECH PROCESSING STRATEGIES FOR PROFOUNDLY DEAF PEOPLE
Authors: Clark Graeme M. 
Published: June 2007

SUMMARY1. The development of speech processing strategies for multiple‐channel cochlear implants has depended on encoding sound frequencies and intensities as temporal and spatial patterns of electrical stimulation of the auditory nerve fibres so that speech information of most importance for intelligibility could be transmitted.2. Initial physiological studies showed that rate encoding of electrical stimulation above 200 pulses/s could not reproduce the normal response patterns in auditory neurons for acoustic stimulation in the speech frequency range above 200 Hz and suggested that place coding was appropriate for the higher frequencies.3. Rate difference limens in the experimental animal were only similar to those for sound up to 200 Hz.4. Rate difference limens in implant patients were similar to those obtained in the experimental animal.5. Satisfactory rate discrimination could be made for durations of 50 and 100 ms, but not 25 ms. This made rate suitable for encoding longer duration suprasegmental speech information, but not segmental information, such as consonants. The rate of stimulation could also be perceived as pitch, discriminated at different electrode sites along the cochlea and discriminated for stimuli across electrodes.6. Place pitch could be scaled according to the site of stimulation in the cochlea so that a frequency scale was preserved and it also had a different quality from rate pitch and was described as tonality. Place pitch could also be discriminated for the shorter durations (25 ms) required for identifying consonants.7. The inaugural speech processing strategy encoded the second formant frequencies (concentrations of frequency energy in the mid frequency range of most importance for speech intelligibility) as place of stimulation, the voicing frequency as rate of stimulation and the intensity as current level. Our further speech processing strategies have extracted additional frequency information and coded this as place of stimulation. The most recent development, however, presents temporal frequency information as amplitude variations at a constant rate of stimulation.8. As additional speech frequencies have been encoded as place of stimulation, the mean speech perception scores have continued to increase and are now better than the average scores that severely‐profoundly deaf adults and children with some residual hearing obtain with a hearing aid.
ELEVATED EPIDERMAL GROWTH FACTOR RECEPTOR LEVELS IN HYPERTENSIVE LYON RAT KIDNEY AND AORTA
Authors: Swaminathan Narayan , Vincent Madeleine , Sassard Jean , Sambhi Mohinder P. 
Published: June 2007

SUMMARY1. The adult spontaneously hypertensive Lyon rats (LH strain) exhibited increased maximal epidermal growth factor (EGF) binding in freshly prepared kidney and aortic tissue membranes compared with age‐matched normotensive (LN) or hypotensive (LL) strains. However, the binding affinity of the receptors to EGF was the same in all the three strains studied. These findings indicate an increased number of EGF receptors (EGFR) in the hypertensive LH strain.2. Protein tyrosine kinase activity associated with the EGFR was also elevated in the LH strain compared with LN or LL strains, indicating that these receptors are functionally active.3. There was a correlation between maximal EGF binding by aortic membranes and blood pressure in individual animals (r = 0.55; P < 0.001).4. Taken together with previously reported similar findings in other models of genetic hypertension, the present results suggest a possible role for increased levels of EGFR in the development and maintenance of genetic hypertension.
REPRODUCIBILITY OF CONVENTIONAL AND POWER SPECTRAL MEASUREMENTS OF CARDIOVASCULAR SYMPATHETIC ACTIVATION IN NORMAL SUBJECTS
Authors: Taverner D. , Nunan TA , Tonkin AL 
Published: June 2007

SUMMARY1. Normal subjects (n = 5; age 20‐42 years; mean resting blood pressure (± 1 s.d.) 116±21/61±11 mmHg) underwent cardiovascular reflex testing five times each. On every occasion systolic blood pressure (SBP) responses to sustained handgrip (GRIP) and cold pressure (COLD) tests were measured and continuous non‐invasive SBP and heart period (RRINT) data were analysed in the frequency domain using fast Fourier transforms. Power spectral (PS) density estimates of high frequency/total power (HF%; a measure of vagal activity), low frequency/HF ratio (LF/HF; a measure mainly of cardiovascular sympathetic activity for heart period) and low frequency/total power (LF%; a proposed measure of sympathetic activity for SBP) at rest, during and 2min after the end of stimuli were calculated.2. The data from the rest and recovery periods did not differ and showed that cardiovascular recovery to baseline measures following sympathetic stimulation occurred within 2 min.3. There was a significant rise in SBP with GRIP and COLD. The LF/HF(RRINT) rose significantly with GRIP, but not with COLD. The LF%(SBP) did not change significantly with GRIP or COLD.4. The SBP and PS analyses showed low intra‐individual reproducibility of responses to reflex tests, with coefficients of variation for PS measures at rest of 25‐41% and on sympathetic stimulation of up to 80%.5. The high variability of these observations indicates that PS methods may not be suitable for the analysis of transient cardiovascular reflexes.
EFFECTS OF EXERCISE ON INTRAOCULAR PRESSURE IN PHYSICALLY FIT SUBJECTS
Authors: Qureshi Imran Ahmad 
Published: June 2007

SUMMARY1. Several studies have shown that exercise reduces intraocular pressure (IOP) in sedentary subjects, but the effects of exercise in physically fit subjects are not fully known. Accordingly, the present study was planned to investigate the effects of exercise on intraocular pressure in physically fit subjects after elimination of those factors that can affect intraocular pressure and have been neglected by previous studies.2. Thirty‐two sedentary males of the same age group were categorized equally into control and experimental groups. Intraocular pressures were measured during and after exercise with the Goldmann applanation tonometer. The experimental group took a supervised exercise programme of 3 months duration. Physical fitness was evaluated by the measurements of maximum oxygen uptake. Each subject was tested twice by the same exercise protocol at an interval of 3 months.3. After 3 months, resting IOP values decreased by 0.31±0.11 (P < 0.05) and 1.37±0.15 mmHg (P<0.001) in control and experimental groups, respectively. The acute decreases following the first exercise test were 4.18±0.41 and 4.38±0.47 mmHg, while after 3 months these values were 4.12±0.45 and 2.69±0.28 mmHg in control and experimental groups, respectively. After exercise conditioning, the mean recovery time was reduced by 43.03%.4. The results are relevant to planning trials in glaucoma. Physical fitness reduces IOP and causes significant attenuation in the IOP response to physical exercise. It would seem reasonable at present not to discourage patients who have glaucoma from light exercise; perhaps, on the contrary, it should be encouraged.
LONG‐TERM EFFECTS OF HIGH CALORIE SUCROSE‐ENRICHED DIET AND STREPTOZOTOCIN‐INDUCED DIABETES ON INSULIN RESISTANCE IN SPONTANEOULY HYPERTENSIVE RATS§
Authors: Sato Toshiaki , Nara Yasuo , Kato Yuzuru , Yamori Yukio 
Published: June 2007

SUMMARY1. The effects of two experimental manipulations on insulin resistance were compared in spontaneously hypertensive rats (SHR) and normotensive Wistar‐Kyoto (WKY) rats. Rats were fed a high calorie sucrose‐enriched diet (high calorie diet) or were made diabetic by the injection of streptozotocin (STZ).2. After treatment with the high calorie diet for 8 weeks, blood pressure increased in SHR, but not in WKY rats. In contrast, STZ treatment decreased blood pressure in SHR, but increased it in WKY rats.3. Plasma glucose levels during oral glucose loading were higher in SHR than in WKY rats. Glucose tolerance was impaired to a greater extent by both the high calorie diet and STZ in SHR than in WKY rats. Hyperinsulinaemia induced by the high calorie diet was severe in SHR compared with WKY rats.4. Abnormalities in lipid metabolism induced by a high calorie diet or STZ‐induced diabetes were more marked in SHR than in WKY rats.5. Steady‐state plasma glucose levels in the insulin suppression test were higher in SHR than in WKY rats, both of which were treated by either the high calorie diet or STZ. These findings indicate that insulin‐stimulated glucose uptake by high calorie diet or STZ‐induced diabetes was impaired to a greater extent in SHR than in WKY rats.6. It is concluded, therefore, that SHR fed on high calorie diet or SHR with STZ‐induced diabetes are suitable models to study the effects of antihypertensive treatment on glucose tolerance, insulin resistance or lipid metabolism as well as blood pressure.
NEURAL CONTROL OF THE CIRCULATION IN HEART FAILURE AND CORONARY ISCHAEMIA: INTRODUCTION
Authors: Zucker Irving H. 
Published: June 2007

SUMMARY1. A large gap in our knowledge of the reflex control of the circulation still exits in the setting of chronic heart failure. This symposium will provide state‐of‐the‐art experimental data on the reflex regulation of the circulation in heart failure and myocardial ischaemia.2. Alterations in arterial baroreflex and cardiopulmonary reflexes contribute to the increase in sympathetic tone in this disease state. Additionally, changes in neurohormones, such as angiotensin, are thought to contribute.3. Coronary ischaemia is associated with activation of both vagal and sympathetic reflexes of cardiac origin. The balance between activation of these two reflexes will determine the ultimate change in sympathetic outflow.4. Sensory endings in the myocardium are exquisitely sensitive to local mediators, such as prostaglandins, oxygenderived free radicals, adenosine and bradykinin.
β‐ADRENOCEPTOR DESENSITIZATION DURING THE DEVELOPMENT OF CANINE PACING‐INDUCED HEART FAILURE
Authors: Vatner Dorothy E. , Sato Naoki , Ishikawa Yoshihiro , Kiuchi Kaname , Shannon Richard P. , Vanter Stephen F. 
Published: June 2007

SUMMARY1. The goal of this review is to emphasize four major points regarding the development of catecholamine desensitization in heart failure (HF).2. Catecholamine desensitization occurs prior to the development of HF (i.e. after 1 day of rapid pacing, physiological responses to β‐adrenoceptor stimulation are depressed by over 50%, yet no evidence of HF is observed for 3‐4 weeks of rapid pacing).3. Multiple mechanisms in the β‐adrenoceptor cascade are involved. In HF there are decreases in β1‐adrenoceptors, high affinity β‐adrenoceptors, adenylyl cyclase activity and messenger RNA and increases in Gi.4. Not all mechanisms appear simultaneously (i.e. early decreases occur in high affinity β‐adrenoceptors and adenylyl cyclase; late increases in Gi and decreases in β‐adrenoceptor density evolves).5. Mechanisms distal to cAMP generation also play a role (i.e. alterations in ryanodine receptor binding and excitationcontraction coupling also occur).
NEURAL RESPONSES TO EXERCISE IN HUMANS: IMPLICATIONS FOR CONGESTIVE HEART FAILURE
Authors: Sinoway Lawrence I. 
Published: June 2007

SUMMARY1. During static handgrip exercise, muscle metaboreceptors are stimulated, evoking the ‘exercise pressor reflex'. As part of this reflex, sympathetic discharge to skeletal muscle is increased. The muscle ‘metaboreceptors’ are thought to be free nerve endings of unmyelinated group IV nerve fibres. These receptors are stimulated by a number of metabolites, including lactic acid, H+, diprotonated phosphate, adenosine and the biproducts of prostaglandin synthesis.2. During chronic, repetitive activity, muscle metabolitesensitive afferents may be desensitized. We speculate that metaboreceptor desensitization also occurs in congestive heart failure (HF). Despite this desensitization, sympathoexcitatory responses to forearm exercise are preserved. This suggests that some other neural system aside from muscle metaboreceptors must be activated to a greater degree in HF. We speculate that in HF the activity of muscle mechanoreceptors is increased. Furthermore, we believe that limb congestion can increase the discharge of muscle mechanoreceptors, thereby evoking nonmetaboreceptor‐mediated increases in sympathetic discharge. Future studies in our laboratory will examine the role limb congestion and decongestion play in evoking muscle mechanoreceptor‐mediated sympathoexcitatory responses.
REFLEXES MEDIATED BY CARDIAC SYMPATHETIC AFFERENTS DURING MYOCARDIAL ISCHAEMIA: ROLE OF ADENOSINE
Authors: Thames Marc D. , Dibner‐Dunlap Mark E. , Minisi Anthony J. , Kinugawa Toru 
Published: June 2007

SUMMARY1. Myocardial ischaemia and infarction activate vagal and sympathetic sensory endings in the ischaemic myocardium, resulting in powerful reflex effects. The vagal afferents are either mechano‐ or chemosensitive, whereas sympathetic afferents may be mechano‐, chemosensitive or both.2. Activation of vagal afferents results in sympathoinhibitory, cardioinhibitory, vasodepressor responses. Cardiac sympathetic afferents activated during myocardial ischaemia mediate sympathoexcitatory, vasoconstrictor cardioaccelerator responses.3. The focus of the present review is on the activation of sympathetic afferents by myocardial ischaemia and on the resulting reflex responses that they mediate.4. These endings are more likely to be activated as the degree of ischaemia progresses from subendocardial towards transmural. They are evenly distributed between the anterior and inferoposterior wall. Although it has been suggested that these endings are activated by bradykinin, recent evidence indicates that they are activated by adenosine released from the ischaemic myocardium. Results from our laboratory indicate that this effect is due to the activation of adenosine A1, but not adenosine A2 receptors.5. Activation of ventricular vagal and sympathetic afferent fibres during myocardial ischaemia in humans is responsible for the autonomic changes observed and, in the case of the sympathetic afferents, for the sensation of angina pectoris.
ANTIHYPERTENSIVE EFFECTS OF dl‐ TETRAHYDROPALMATINE: AN ACTIVE PRINCIPLE ISOLATED FROM CORYDALIS
Authors: Lin MT , Chueh FY , Hsieh MT , Chen CF 
Published: June 2007

SUMMARY1. The effects of dl‐tetrahydropalmatine (dl‐THP) on cardiovascular function and hypothalamic release of monomines were assessed in rats under urethane anaesthesia.2. Intravenous administration of dl‐THP (1‐10 mg/kg) produced hypotension, bradycardia, a decrease in hypothalamic serotonin and noradrenaline release and in increase in hypothalamic dopamine release in rats.3. Intrahypothalamic administration of DOI (a serotonergic 5‐HT2 receptor antagonist) or apomorphine (a dopamine D2‐receptor agonist) produced the opposite effects and reversed dl‐THP‐induced hypotension and bradycardia.4. The data suggest that dl‐THP acts through the 5‐HT2 and/or D2‐receptor antagonism in the hypothalamus to induce hypotension and bradycardia in rats.
A FAMILY OF NOVEL ACTIN‐INHIBITING MARINE TOXINS
Authors: Saito Shin‐ya , Karaki Hideaki 
Published: June 2007

SUMMARY1. We have examined the effects of marine toxins with a macrolide structure on actin. These toxins include mycalolide B, aplyronine A and bistheonellide A.2. Measuring actin polymerization by monitoring fluorescent intensity of pyrenyl‐actin, mycalolide B did not accelerate the actin polymerization but quickly depolymerized F‐actin. In contrast, cytochalasin D, which inhibits actin polymerization by binding to the barbed end of F‐actin, accelerated actin nucleation and depolymerized F‐actin at a slower rate.3. Analysing the kinetics of depolymerization by monitoring the rate of spontaneous depolymerization of F‐actin under the unpolymerizable state or the rate of polymerization where F‐actin was seeded as a nucleus, mycalolide B was suggested to sever F‐actin.4. The relationship between the concentration of total actin and F‐actin at different concentrations of mycalolide B suggests that mycalolide B forms a 1:1 complex with G‐actin. Viscometry and electron microscopic observations further suggest that the actin filament was depolymerized by mycalolide B. Furthermore, mycalolide B suppressed actin‐activated myosin Mg2+‐ATPase activity, although cytochalasin D did not. Aplyronine A has similar effects on actin.5. Bistheonellide A also depolymerized F‐actin and sequestered G‐actin by forming a 1:2 complex with G‐actins, but, its severing effect was not detected. We conclude that mycalolide B, aplyronine A and bistheonellide A are novel types of actin‐depolymerizing agents, the mechanism of action of which is different from that of cytochalasin D. These structurally related marine toxins may be categorized as ‘actin depolymerizing macrolides’ and may serve as novel pharmacological tools for analysing actin‐mediated cell functions.
TETRANDRINE AS A CALCIUM ANTAGONIST
Authors: Takemura Haruo , Imoto Kenshi , Ohshika Hideyo , Kwan Chiu‐Yin 
Published: June 2007

SUMMARY1. The Ca2+‐antagonism of tetrandrine (TET) on the Ca2+ mobilization in various types of cells were reviewed. Inositol trisphosphate (IP3)‐generating drugs were used as Ca2+‐mobilizing agonists and the effects were compared with those produced by using the microsomal Ca2+‐ATPase inhibitor thapsigargin (TG), which is a tool for analysing Ca2+ which is a tool for analysing Ca2+ store ‐regulated Ca2+ entry (capacitative Ca2+ entry).2. In rat phaeochromocytoma PC12 cells, 100 μmol/L TET abolished high K+ (30 mmol/L)‐induced sustained increases in cytoplasmic Ca2+ concentrations ([Ca2+]i) and partially inhibited bradykinin (1 μmol/L)‐ or TG (100 nmol/L)‐induced Ca2+ entry.3. In NIH/3T3 fibroblasts and rat parotid acinar cells, 100 μmol/L TET abolished Ca2+ entry induced by bombesin (1 μmol/L) and carbachol (100 μmol/L), respectively, or TG (100 nmol/L). However, in the human leukaemia T cell line Jurkat, 100 μmol/L TET did not inhibit Ca2+ entry evoked by either the anti‐CD3 antibody OKT3 (10 mg/L) or TG (100 nmol/L).4. In rat glioma C6 cells, the effects of TET on Ca2+ mobilization were further examined. At a high concentration, TET (300 μmol/L) alone did not affect [Ca2+]i in C6 cells. Tetrandrine inhibited the peak and sustained increases in [Ca2+]i induced by bombesin and TG in a dose‐dependent manner. Although TET or TG did not produce increases in IP3, TET did inhibit increases in IP3 produced by bombesin.5. Our results suggest that the action of TET on Ca2+ entry is dependent on cell types and that TET inhibits both Ca2+ entry from the extracellular medium and Ca2+ release from intracellular stores in rat glioma C6 cells.
PLASMA FOLLISTATIN CONCENTRATIONS INCREASE FOLLOWING LIPOPOLYSACCHARIDE ADMINISTRATION IN SHEEP
Authors: Klein Rudi , Clarke Iain J. , Hedger Mark P. , Robertson David M. 
Published: June 2007

SUMMARY1. The effect of inflammation induced by lipopolysaccharide (LPS) injection on plasma follistatin (FS) concentrations was investigated.2. Plasma FS and tumour necrosis factor‐α concentrations increase following LPS administration in ewes.3. The rise in FS is similar, but more sustained, to that previously observed after surgery.4. These results indicate a possible functional link between FS, inflammation and the acute‐phase response.