bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTS OF PREGNANCY AND PROGESTERONE METABOLITES ON REGULATION OF SYMPATHETIC OUTFLOW
Authors: Heesch Cheryl M. , Rogers Richard C. 
Published: June 2007

SUMMARY1. Pregnancy is characterized by a 40% increase in blood volume and cardiac output, a decrease in arterial blood pressure and thus a substantial decrease in total peripheral resistance. The aims of the experiments described in this manuscript were: (i) to determine if pregnancy resulted in alterations in baroreflex control of sympathetic outflow; and (ii) to evaluate possible mechanisms for pregnancy‐induced changes in control of sympathetic outflow.2. Arterial baroreflex control of efferent renal sympathetic nerve activity was examined in female pregnant and non‐pregnant normotensive Sprague‐Dawley and Wistar‐Kyoto rats. In both rat strains, pregnancy was associated with a decrease in baseline arterial pressure, a shift in the baroreflex function curve to a lower operating pressure range and an attenuated ability to reflexly increase sympathetic outflow above baseline levels during a hypotensive challenge. Pregnant Sprague‐Dawley rats retained their ability to respond to a hypertensive challenge, whereas pregnant Wistar‐Kyoto rats exhibited a decreased sensitivity to hypertensive as well as hypotensive challenges.3. The inhibitory amino acid transmitter, GABA, mediates baroreflex sympatho‐inhibition within the rostral ventral lateral medulla (RVLM) of the brainstem. Since 3α‐OH dihydroprogesterone (3α‐OH‐DHP), a major metabolite of progesterone, is elevated in pregnancy and has been reported to potentiate central nervous system GABAainhibitory responses, experiments were performed to determine if effects of this metabolite of progesterone could contribute to the pregnancy associated changes in control of sympathetic outflow. Acute intravenous administration of 3α‐OH‐DHP to virgin female Sprague‐Dawley rats resulted in progressive changes in the baroreflex function curve that mimicked the effects of pregnancy.4. Preliminary experiments in which the GABAaagonist, isoguvacine, and 3α‐OH‐DHP were micro‐injected into the RVLM of virgin female rats suggest that the 3α‐OH metabolite of progesterone potentiates sympatho‐inhibitory effects of GABAareceptor activation in the RVLM.5. In conclusion, acute administration of 3α‐OH‐DHP to virgin female rats mimics the effects of pregnancy on baroreflex control of sympathetic outflow. These results are consistent with potentiation of GABAergic sympatho‐inhibition by circulating levels of the major metabolite of progesterone during pregnancy.
DEGRANULATION OF RAT SALIVARY GLANDS FOLLOWING TREATMENT WITH RECEPTOR‐SELECTIVE AGONISTS
Authors: Peter Birgit , Waarde Maria A. W. H. Van , Vissink Arjan , 's‐Gravenmade Eduard J. , Konings Antonius W. T. 
Published: June 2007

SUMMARY1. The aim of this study was to find a drug that induces an almost complete degranulation of secretory cells in rat parotid and submandibular glands.2. Phenylephrine (α‐adrenergic), isoproterenol (β‐adrenergic) and mecholine (muscarinic cholinergic) were tested. Time and degree of maximal depletion of acinar and granular convoluted tubule cells were determined morphologically.3. Following phenylephrine‐injection (5 mg/kg or 10.2 mg/kg, i.p.), no effect on the acinar granulation level was observed in either of the glands, while about 50–60% granular convoluted tubules were degranulated for at least 120–180 min post‐injection.4. With isoproterenol (5, 10, 40, 70 or 100 mg/kg, i.p.), degranulation of 100% of the acinar cells in the parotid and 80% of the acinar cells in the submandibular gland was observed 90 min post‐injection. Granular convoluted tubule cells did not respond to this β‐adrenergic drug.5. Mecholine (3.75 or 7.5 mg/kg, i.p.) induced mainly degranulation of granular convoluted tubule cells (about 50% after 120 min). Numbers of granulated acinar cells decreased only slightly in both glands (about 10%, 90–120 min).6. From this study it appears that with a relatively low dosage (5 mg/kg, i.p.) of isoproterenol, a high level of degranulation can be induced in acinar cells of rat parotid and submandibular glands without toxic side effects. Concerning granular convoluted tubules, only moderate degranulation was observed with phenylephrine and mecholine, respectively.
SEX DIFFERENCES AND THE EFFECT OF GONADECTOMY ON MORPHINE‐INDUCED ANTINOCICEPTION AND DEPENDENCE IN RATS AND MICE
Authors: Ali B. H. , Sharif S. I. , Elkadi A. 
Published: June 2007

SUMMARY1. Differences between sexes and the effect of bilateral surgical gonadectomy on the response to morphine analgesia and dependence were examined in rats and mice.2. The analgesic response to morphine (5 mg/kg) was assessed by the hot plate and the abdominal constriction tests. Dependence was induced by injecting morphine at increasing doses (5–160 mg/kg) for 6 consecutive days and withdrawal signs elicited by injecting naloxone (2.5 mg/kg).3. The base line reaction times in the intact control, shamoperated and gonadectomized animals of either sex were not significantly different from each other.4. After treatment with morphine, the percentage increase in the reaction time in gonadectomized male and female rats and in gonadectomized male mice was significantly higher than in their respective controls.5. The increase in the reaction time, after morphine treatment, was significantly higher in gonadectomized female rats than in gonadectomized male rats.6. Naloxone‐induced withdrawal signs in morphine‐dependent gonadectomized rats and mice were not significantly different from those in sham‐operated controls. However, female rats in both groups exhibited a significantly higher number of escape jumping responses than males.
ESTERASE COMPARISON IN NEUROBLASTOMA CELLS OF HUMAN AND RODENT ORIGIN
Authors: Ehrich Marion , Veronesi Bellina 
Published: June 2007

SUMMARY1. Activities of acetylcholinesterase (AChE), neuropathy target esterase (NTE), and carboxylesterase (CbxE) were compared in neuroblastoma cells of human origin (SH‐SY5Y) and murine origin (NB41A3).2. Mouse neuroblastoma cells had lower specific activities of NTE and CbxE than did human neuroblastoma cells; specific activities in the murine cells correlated with specific activities in mouse brain.3. AChE activities in mouse and human neuroblastoma cells were considerably lower than AChE activities in mouse or hen brain.4. Inhibition of esterases did not demonstrate interspecies differences for 12 of the 17 anti‐esterase compounds tested with human and mouse neuroblastoma cells.
THE ROLE OF ANGIOTENSIN CONVERTING ENZYME AND NITRIC OXIDE IN THE ENHANCED SYSTEMIC DEPRESSOR RESPONSES TO BRADYKININ IN PREGNANT RATS
Authors: Chu Z. M. , Beilin L. J. 
Published: June 2007

SUMMARY1. In the present study we have examined the effects of angiotensin I converting enzyme (ACE) inhibition and nitric oxide (NO) synthesis inhibition on bradykinin (BK) depressor responses in pregnancy in both Wistar‐Kyoto (WKY) and spontaneously hypertensive rats (SHR).2. Ramipril (10 mg/kg, i.v.) significantly reduced mean blood pressure (MBP) in all animals. Further administration of L‐nitro‐arginine (L‐NOARG, 20 mg/kg, i.v.) increased MBP to a less extent in pregnant WKY and to a similar level in pregnant SHR compared with their non‐pregnant controls (controls), respectively.3. Systemic depressor responses to BK were increased in pregnant WKY and were unchanged in pregnant SHR as compared with their controls. Ramipril (10 mg/kg, i.v.) potentiated BK responses in all groups, and abolished the differences between pregnant and non‐pregnant WKY. Further administration of L‐NOARG (20 mg/kg, i.v.) did not further influence BK responses in all groups.4. The results suggest that systemic depressor responses to BK are enhanced in pregnant WKY and unchanged in pregnant SHR. Decreased ACE activity may contribute to enhanced systemic depressor responses to BK in pregnant WKY.
POSTNATAL DEVELOPMENT OF RESPONSES TO AIRFLOW OBSTRUCTION
Authors: Harding Richard , Jakubowska Alexandra E. , McCrabb Graeme J. 
Published: June 2007

SUMMARY1. Obstruction of the upper airway could be an initiating factor in the Sudden Infant Death Syndrome (SIDS). Responses to upper airway obstruction include augmentation of respiratory efforts, active dilation of the upper airway and electrocortical arousal. Vulnerable individuals may fail to mount these responses effectively.2. Respiratory and arousal responses to obstruction of the upper airway have been investigated in newborn lambs. In conscious lambs, nasal obstruction causes a profound augmentation of inspiratory efforts, mild asphyxiation and eventual formation of an oral airway. The ability to establish an oral airway involves both chemoreception and mechanoreception and improves with age.3. In sleeping lambs, obstruction of tidal airflow leads to progressive hypoxaemia, augmentation of inspiratory efforts, bradycardia and arousal. Arousal occurs earlier and with less hypoxaemia and bradycardia in non‐REM sleep than in REM sleep. Arousal occurs after inspiratory efforts have increased to the same extent during both sleep states, suggesting that mechanoreception, or a sense of inspiratory effort, is important in initiating arousal.4. Obstruction of nasal tubes tends to cause arousal from sleep earlier, and with less hypoxaemia and less augmentation of inspiratory effort, than when a more compliant face mask is obstructed. This supports the suggestion that mechanoreception, which may be involved in the perception of inspiratory effort, is a determinant of arousal.5. With increasing postnatal age, lambs become less arous‐able in response to airflow obstruction when in REM sleep. This suggests that lambs may become progressively more vulnerable to the effects of airway obstruction during the immediate newborn period.6. The ability to respond to upper airway obstruction is well developed at birth in normal lambs. Responses are affected by sleep‐wake states, mode of airflow obstruction and postnatal age. Future studies will determine whether prenatal compromises, such as those thought to have influenced neural development in some SIDS victims, affect the ability of the neonate to respond adequately to upper airway obstruction.
EFFECTS OF LIFESTYLE, COPING AND WORK‐RELATED STRESS ON BLOOD PRESSURE IN OFFICE WORKERS
Authors: Lindquist T. L. , Beilin L. J. , Knuiman M. 
Published: June 2007

SUMMARY1. The relative importance of perceived stress compared with coping behaviours and ‘lifestyle’ characteristics known to influence blood pressure were studied in 337 male and 317 female office workers.2. Males had significantly higher mean systolic (P<0.01; t‐test, 652 d.f.) and diastolic (P<0.01; t‐test, 652 d.f.) blood pressure and unhealthier lifestyles than females, particularly in the areas of alcohol intake (P<0.01; t‐test, 653 d.f.) and diet (P= 0.01; t‐test, 663 d.f.).3. In males drinking alcohol was correlated to job and home/work stress (P<0.05), and eating more atherogenic foods was correlated to home/work stress (P<0.05).4. Coping by food and drug consumption was correlated with job and home/work stress (P <0.05) in males; avoidance/ denial coping was correlated with job stress in both males and females (P<0.001) and to home/work stress (P<0.001) in males only. Blood pressure was not correlated with stress in males or females.5. In age‐adjusted regression analyses body mass index (BMI) and lifestyle (physical inactivity, alcohol consumption and diet) made significant contributions to systolic (P= 0.02) and diastolic (P<0.01) blood pressure and, in separate analyses, coping contributed significantly to diastolic blood pressure (P<0.01) in males. Stress made no additional contribution to blood pressure in either analysis.6. After including age, BMI, lifestyle and coping in males ‘lifestyle’ still contributed to systolic and diastolic blood pressure and coping made a significant additional contribution to diastolic blood pressure. Neither lifestyle or coping contributed significantly to blood pressure in females.7. Thus obesity, alcohol, physical activity and diet had dominant effects on blood pressure; while any effects of job stress were indirect and related to maladaptive coping, particularly in males.
PROLACTIN INDUCED ANALGESIA IS DEPENDENT ON ATP SENSITIVE POTASSIUM CHANNELS
Authors: Shewade D. G. , Ramaswamy S. 
Published: June 2007

SUMMARY1. The role of ATP sensitive potassium channels in the analgesic activity of prolactin (PRL) was studied in mice using glibenclamide and minoxidil, a blocker and an opener of these channel, respectively.2. Re‐treatment with glibenclamide attenuated the analgesic activity of PRL while treatment with minoxidil potentiated the activity.3. It is concluded that PRL, similar to morphine, utilizes ATP sensitive potassium channels in eliciting the analgesic response.
REGIONAL DIFFERENCE OF ENDOGENOUS ATP RELEASE IN THE PULMONARY ARTERY OF RABBITS
Authors: Takeuchi Koichi , Shinozuka Kazumasa , Ishii Reiko , Hashimoto Takao 
Published: June 2007

SUMMARY1. The release of adenyl purines such as ATP, ADP, AMP and adenosine, from the pulmonary artery trunk (PAT), extra‐pulmonary artery (EPA) and intrapulmonary artery (IPA) were compared.2. The amount of basal overflow of adenyl purines from the PAT was significantly smaller than those from EPA and IPA. There was no significant difference between the amount of the overflow from EPA and PAT.3. Methoxamine, an α1‐adrenoceptor agonist, significantly increased the overflow of adenine nucleotides from the PAT, EPA and IPA, but did not increase those of adenosine. Methoxamine‐induced release of adenyl purines from IPA was significantly larger than those from EPA and PAT.4. These results suggest that an α,‐adrenoceptor‐mediated mechanism for ATP‐release is not homogeneously distributed in the pulmonary artery and a larger amount of ATP may be released in the peripheral part of the artery.
EFFECTS OF RECOMBINANT HUMAN ERYTHROPOIETIN ON BLOOD PRESSURE AND RENAL FUNCTION IN SHR WITH CHRONIC RENAL FAILURE
Authors: Kohzuki Masahiro , Yasujima Minoru , Kanazawa Masayuki , Yoshida Kazunori , Sato Tokutaro , Abe Keishi 
Published: June 2007

Summary1. The effects of chronic administration of erythropoietin (EPO) on blood pressure and renal function in rats with ablation of renal mass were assessed.2. Spontaneously hypertensive rat were subjected to 5/6 nephrectomy (5/6Nx). Four weeks after the operation, the rats were randomly allocated to vehicle, EPO 20 IU/kg i.p., or EPO 100 W/kg i.p. (both given twice a week) for 4 weeks.3. Marked anaemia was noted in SHR‐5/6Nx. EPO caused a significant increase in haematocrit at a high dose but not at a low dose. A dose dependent relationship was noted in the EPO‐induced rise in the systolic blood pressure.4. EPO dose‐dependently increased urinary protein excretion. It also increased blood urea nitrogen and serum creatinine levels.5. These results suggest that EPO ameliorates anaemia and severely accelerates renal failure in SHR‐5/6Nx. They also suggest that anaemia can be a haemodynamieally favourable adaptation to chronic renal disease and that its correction may have adverse renal haemodynamic and structural consequences.
DIFFERENCES IN CULTURED CARDIAC FIBROBLAST POPULATIONS ISOLATED FROM SHR AND WKY RATS
Authors: Klett Christoph P. R. , Palmer Abraham , Gallagher Ann‐Marie , Rioseco‐Camacho Natalia , Printz Morton P. 
Published: June 2007

Summary1. The mechanisms whereby angiotensin converting enzyme inhibitors reverse cardiac remodelling appear to involve angiotensin and/or bradykinin receptors. Previously we reported that cultured rat cardiac fibroblasts express angiotensin II (AII) receptors. In the present study we compared AII receptor binding, gene expression of angiotensinogen and the AII, Subtype 1A (AT1A) receptor, as well as morphological changes induced by selected hormonal treatments in cultured fibroblasts derived from SHRLJ or WKYLJ rats.2. Fibroblasts were isolated from adult rat left ventricle by either collagenase B or collagenase P digestion. Collagenase B yielded cell preparations from SHRLJ which grew slower than cells from WKYLJ rats and expressed nearly two‐fold fewer AII receptors (compared to WKYLJ) while collagenase P yielded SHRLJ cells with similar binding and growth properties to WKYLJ. A good correlation was observed between receptor binding and AII receptor, type 1A (AT1A) mRNA concentrations. In the presence of steroids collagenase B cells showed a higher tendency to transform towards a preadipocyte cell type, estimated by the formation of lipid containing vacuoles/cell, while collagenase P cells, mainly the SHRLJ type, start to differentiate toward a myofibroblast‐like cell type in the presence of AII, as calculated by the expression of α‐smooth muscle actin.3. From the results obtained in this study it is evident that a subset of fibroblasts can be isolated from the SHRLJ heart using collagenase B or P which differ in growth rates, AII receptor binding, AT1A and angiotensinogen mRNA levels, morphology and steroid responsiveness when compared to fibroblasts isolated from cardiac WKYLJ tissue.
RECEPTOR DENSITY IN THE RAT HEART FOLLOWING ISCHAEMIA AND PROLONGED REPERFUSION
Authors: de Jong W. , Lukovic L. , Jones C. R. , Petty M. A. 
Published: June 2007

Summary1. The free radical scavenger MDL 73,404 decreases infarct size and improves heart performance after myocardial ischaemia and prolonged reperfusion. In the present study the possibility that changes in receptor density might contribute to the MDL 73,404‐induced increase in contractility has been investigated in rats subjected to myocardial ischaemia and 8 days of reperfusion.2. Both in saline‐ and MDL 73,404‐treated rats a significant decrease in β1‐ and increase in β2‐adrenoceptor densities was apparent in the infarcted tissue.3. In non‐infarcted septum and right ventricle tissue ischaemia followed by reperfusion tended to increase the density of β2‐adrenoceptors which was significantly increased after MDL 73,404 treatment.4. The increased density of β2‐receptors in the non‐infarcted tissue may contribute to the MDL 73,404 induced improvement of cardiac performance.
FOETAL METABOLISM, PLACENTAL TRANSFER AND ORIGIN OF GASTRIN RELEASING PEPTIDE IN THE SHEEP
Authors: Shulkes Arthur , Whitley Jane , Hardy Kenneth , Giraud Andrew 
Published: June 2007

SUMMARY1. Plasma gastrin relesing peptide (GRP) is elevated in the foetal and maternal circulations of pregnant sheep. To determine the mechanisms for this increase the synthesis, secretion rate, metabolism and placental transfer of GRP were measued.2. Foetal metabolic clearance rate of GRP was significantly increased (P < 0.05) compared to the non‐pregnant eve (1909 ± 2.6 (s.e.m.) and 11.8 ± 2.0 mL/min per kg, respectively). Production rate of GRP in the foetus was four in the foetus was four‐fold higher than in the non‐pregnant ewe reflecting the combination of the increased basal concentration and metabolic celarance rate in the foetus.3. Infused GRP did not cross the placenta. However, endogenous GRP was higher in the umbilical vein than in the umbilical artery, suggesting a uteroplacental origin for some of the GRP in the foetal circulation.4. Gastrin releasing peptide mRNA was synthesized in the pregnant endometrium with lower amounts found in the pregnant myometrium. No GRP mRNA was detected in the amnoin or chorioallantois.5. The results show that the previously reported increase in foetal concentration of GRP is from foetal and uteroplacental sources and is not a result of immaturity of clearance mechanims but rather from an increased production of GRP. With the demonstation that the uteroplacenatal unit synthesizes and stores GRP, additional studies on the regulation of GRP production from these sources are warranted.
MANUAL DEXTERITY: HOW DOES THE CEREBRAL CORTEX CONTRIBUTE?
Authors: Darian‐Smith Ian , Galea Mary P. , Darian‐Smith Corinna 
Published: June 2007

SUMMARY1. Manual dexterity, of great evolutionary significance to the primates, ranges in complexity from the precise opposition of finger and thumb to Brendal playing Mozart. All dexterity depends on a sustained and rapid transfer of sensorimotor information between the cerebral cortex and the cervical spinal cord.2. Multiple separate corticospinal neuron populations originate from cortical areas four, the supplementary motor area, anterior cingulate, postarcuate, parietal and insular cortex. Each corticospinal neuron population projects in parallel to all spinal segments, and has a distinctive pattern of terminations.3. Each corticospinal neuron population has a unique thalamic input which can relay particular sensorimotor information from the sense organs, cerebellum and basal ganglia. The overall structural framework of these sensorimotor pathways, with many parallel corticospinal channels, with interconnections in the cerebral cortex and spinal cord to enable crosstalk between the channels, is that needed for parallel distributed processing, which would enable the very rapid transfer of information between the cerebral cortex and spinal cord needed for any sophisticated use of the hand.4. Hemisection of the cervical spinal cord in the macaque results in an immediate hemiplegia, with subsequent remarkable although incomplete recovery of hand and finger movements. The only direct corticospinal input to the hemicord caudal to the hemisection, even after 3 years, is the ∼ 10% of fibres which cross the midline caudal to the lesion: the fibres ‘spared’ by the hemisection. A matching ‘sparing’ of somatosensory input from the paresed limb also occurs. No regeneration of the interrupted pathways has been visualized using modern tracer techniques.5. Cervical hemisection permanently reduces the number of parallel channels which transmit information between cortex and spinal cord, but does not reduce their cortical origins nor the neuron populations targeted in the spinal cord. We infer that the content of the information that can be transmitted between the cortex and spinal cord is not greatly changed, but the rate of transmission of this information is sharply reduced, and is the ‘bottleneck’ that limits the complete recovery of dexterity following hemisection. The remarkable recovery that does occur presumably reflects more economic transmission of information by the few spared channels. We guess that this involves substantial synaptic reorganization not visualized by the procedures we have used.