bluuebunny/crossref_metadata_2025 huggingface dataset:
INVOLVEMENT OF OXIDATIVE AND L‐ARGININE‐NO PATHWAYS IN THE NEUROTOXICITY OF DRUGS OF ABUSE IN VITRO
Authors: Cerruti C. , Sheng P. , Ladenheim B. , Epstein C. J. , Cadet J‐L.
Published: June 2007

1. Inhibitors of nitric oxide (NO) formation or ADP‐ribosylation attenuate methamphetamine (METH)‐ and methyl‐enedioxymetamphetamine (MDMA)‐induced neurotoxicity on dopaminergic and serotonergic cells in primary cultures.

2. They also prevent METH‐induced reactive gliosis in dopaminergic cultures.

3. Overexpression of superoxide dismutase (SOD) in cells obtained from SOD‐transgenic mice also attenuates drug‐induced toxicity.

4. These data indicate a role for oxygen‐based and NO free radicals in the mechanisms of cell death associated with drugs of abuse in vitro.
VALIDATION AND IN VITRO NEUROTOXICITY
Authors: Green Sidney
Published: June 2007

1. Validation of in vitro systems for studying neurotoxicants generally has not been accomplished, although in vitro tests have been used as screens to identify potential neurotoxic hazards and to study mechanisms.

2. A number of factors need to be taken into account when a test is validated: (i) a rationale for developing the test; (ii) clear biological or pathophysiological relevance of the endpoint to the effect detected in vivo; (iii) a standardized protocol and evidence of intra‐ and interlaboratory reproducibility; (iv) testing of chemicals representative of the categories of interest, including very toxic, moderately toxic and relatively non‐toxic substances; and (v) a method to statistically evaluate the data.

3. Proper validation should lead to methods which can be used by regulatory agencies to make decisions regarding hazard/risk.
MECHANISMS OF INCREASED AIRWAY MICROVASCULAR PERMEABILITY: ROLE IN AIRWAY INFLAMMATION AND OBSTRUCTION
Authors: Goldie Roy G. , Pedersen Karen E.
Published: June 2007

1. Airway inflammation is a signal feature of human asthma, as is bronchial obstruction and the resultant airflow limitation. An obligatory accompaniment to airway inflammation is increased airway microvascular permeability, which in turn is causally related to bronchial oedema. In this review, we have attempted to describe the mechanisms of increased airway microvascular permeability and its relationship to oedema, bronchial obstruction and the hyperreactivity to spasmogenic stimuli which are such common features of asthma.

2. It is now clear that bronchial obstruction in chronic asthma can involve bronchial wall oedema and swelling in addition to reversible, elevated airway smooth muscle tone, mucus hypersecretion and airway plugging and potentially permanent structural changes in airway architecture. Inflammatory mediators released in the airway wall in asthma including histamine, platelet‐activating factor, leukotrienes and bradykinin are potent inducers of increased bronchial microvascular permeability and are thus promoters of bronchial oedema, airway wall swelling and reduction in luminal calibre.

3. The primary mechanism believed to underlie acute increases in microvascular permeability is contraction of post‐capillary venular endothelial cells, resulting in the formation of gaps between otherwise tightly associated cells. Extravasated plasma distributes to the interstitial spaces in the airway wall, resulting in oedema and swelling, but may also traverse the epithelium and collect in the airway lumen.

4. Luminal plasma may compromise epithelial integrity and cilial function and thus reduce mucus clearance. Plasma proteins may also promote the production of viscous mucus and the formation of luminal mucus plugs. Together, these effects can result in or contribute to airway obstruction and hyper‐responsiveness.

5. An understanding of such mechanisms can provide insight concerning novel and effective anti‐asthma therapies.
ANGIOTENSIN‐CONVERTING ENZYME AND ANGIOTENSINOGEN GENES IN PATTERNS OF LEFT VENTRICULAR HYPERTROPHY AND IN DIASTOLIC DYSFUNCTION
Authors: Wong K. K. , Summers K. M. , Burstow D. J. , West M. J.
Published: June 2007

1. The association of different patterns of left ventricular hypertrophy and diastolic dysfunction with angiotensin converting enzyme (ACE) genotypes or angiotensinogen dinucleotide repeat alleles were studied in human subjects.

2. Three abnormal patterns of hypertrophy (remodelled, eccentric and concentric) were associated with a history of hypertension. The presence of remodelled or concentric hypertrophy was associated with diastolic dysfunction.

3. There was no difference between the frequencies of the ACE genotypes in normotensive and hypertensive subjects, in subjects with normal ventricles and those with different patterns of left ventricular hypertrophy, nor in subjects with normal and abnormal diastolic function. Similarly, there was no difference between the relative frequencies of AGT alleles in the same clinical subgroups.

4. We conclude that in this population of hospital patients, variants of the ACE and AGT genes do not contribute to the presence of different patterns of hypertrophy or to diastolic dysfunction.
EFFECT OF SODIUM VALPROATE ON NALOXONE‐STIMULATED ACTH AND CORTISOL RELEASE IN HUMANS
Authors: Torpy D. J. , Grice J. E. , Hockings G. I. , Crosbie G. V. , Walters M. M. , Jackson R. V.
Published: June 2007

1. Gamma‐aminobutyric acid (GABA) and endogenous opioids each inhibit hypothalamic CRH secretion. In humans, the opioid antagonist, naloxone, stimulates the release of CRH, and so of ACTH and cortisol, while alprazolam, an indirect GABAA agonist, blocks naloxone‐induced ACTH and cortisol secretion. Sodium valproate (SV) inhibits ACTH release in response to CRH, metyrapone and substance P. We hypothesized that, if this action is GABAA‐mediated, SV should also inhibit naloxone‐stimulated ACTH release.

2. We studied five healthy volunteers in randomized, double‐blind, placebo‐controlled afternoon studies with SV 400 mg, given 180 min before i.v. naloxone 125 μg/kg bodyweight. Plasma concentrations of ACTH, cortisol and SV were measured at intervals during the experiments.

3. SV had no effect on the mean integrated ACTH and cortisol responses to naloxone; ACTH. 165 ± 21 versus 284 ± 40 pmolmin per L, P= 0.08; cortisol: 10.5 ± 1.9 versus 12.8 ± 1.2 nmolmin per L‐3, P= 0.14, placebo/nal versus SV/nal respectively. Basal ACTH and cortisol levels were also not significantly altered by SV (P>0.30). Mean SV levels were not significantly different between SV/nal and SV/placebo studies (P>0.50).

4. In conclusion, SV had no effect on naloxone‐induced ACTH and cortisol release in normal humans at the dose and plasma drug concentrations studied. This contrasts with the potent inhibitory effect of alprazolam, and suggests that the effect of SV on the human hypothalamic‐pituitary‐adrenal axis may not be through a GABAA‐mediated mechanism. Alternatively, higher plasma SV levels or more sustained exposure to SV may be necessary to inhibit hypothalamic secretion of CRH.
POWER SPECTRAL ANALYSIS OF HEART RATE VARIABILITY DURING GRADED HEAD‐UP TILTING IN PATIENTS WITH VASODEPRESSOR SYNCOPE
Authors: Prinz‐Zaiss M. , Yeap A. N. , Moguilevski V. , Trigg L. , McGrath B. P.
Published: June 2007

1. Two groups of age‐ and sex‐matched subjects, eight healthy controls and 10 patients, suffering from recurrent vasodepressor syncope, participated in a study to examine autonomic function and sequential changes in power distribution of heart rate (HR) variability during graded head‐up tilt.

2. The following autonomic function tests were performed valsalva ratio, HR responses to deep breathing and posture, BP responses to sustained handgrip and postural change. Each subject was tilted at 15°, 30°, 45°, 60° and 80° head‐up, each for 15 min, or until symptoms occurred. The eight control subjects completed the tilt study without any symptoms, while all 10 patients developed presyncope and/or syncope at various tilt angles.

3. Resting blood pressure (BP) was lower in the patient group, while resting HR, autonomic function tests and resting HR variability components were similar in the two groups.

4. The control group showed a progressive increase in low frequency power component (LF) from supine to end tilt (ΔLF 20.06 ± 14.50%) and a progressive fall in high frequency (HF) component (ΔHF—24.62 ± 10.64%). In contrast, in the patient group, LF fell during tilt in the presyncope period (ΔLF ‐10.57 ± 12.93%, P < 0.01 vs control group). HF and HF: LF ratio responses did not differ significantly in the two groups.

5. At end tilt, the increase in plasma noradrenaline was significantly greater in the control group than in the patient group (ΔNA 0.83 ± 0.27 vs 0.28 ± 0.14 pmol/mL, P < 0.01). Plasma adrenaline: noradrenaline ratio at end tilt did not change in the control group, but increased significantly in the patient group (supine 0.07 ± 0.03, end tilt 0.16 ± 0.09, P < 0.05).

6. It was concluded that sympathetic withdrawal plays a major role in the mechanism of vasodepressor syncope.
LAPAROSCOPIC ADRENALECTOMY FOR ADRENAL TUMOURS CAUSING HYPERTENSION AND FOR ‘INCIDENTALOMAS’ OF THE ADRENAL ON COMPUTERIZED TOMOGRAPHY SCANNING
Authors: Rutherford John C. , Gordon Richard D. , Stowasser Michael , Tunny Terry J. , Klemm Shelley A.
Published: June 2007

1. In a 19 month period from June 1993 to December 1994, 60 patients (mean age 54.8 ±.5 years s.e.m.; 32 males, 28 females) underwent unilateral laparoscopic adrenalectomy by one of us (JCR) for the treatment of hypertension due to primary aldosteronism (n = 48), phaeochromocytoma (n = 3) and cortisol‐producing adenoma (n = 1) or to remove adrenal masses incidentally discovered on abdominal computerized tomography scanning (‘incidentaloma’) performed for other reasons (seven adenomas without biochemical evidence of excessive steroid hormone or catecholamine secretion and one carcinoma autonomously producing cortisol).

2. Compared with conventional open procedures, laparoscopic adrenalectomy was associated with reduced recovery time and a low complication rate (one pulmonary embolus and one port site incisional hernia).

3. Operation time with experience approximates that of open procedures (60 min), but is significantly longer in obese than in non‐obese patients, and in males than in females.

4. Patients with adrenal causes of hypertension were cured or significantly improved by laparoscopic unilateral adrenalectomy.

5. Because of our concern regarding malignant potential of incidentalomas and high patient acceptance of laparoscopic techniques, we have reduced our size criteria for removal of incidentalomas.
CROSS‐SECTIONAL STUDY OF A MICROSATELLITE MARKER IN THE LOW DENSITY LIPOPROTEIN RECEPTOR GENE IN OBESE NORMOTENSIVES
Authors: Griffiths Lyn R. , Nyholt Dale R. , Curtain Robert P. , Gaffney Philip T. , Morris Brian J.
Published: June 2007

1. The low density lipoprotein receptor is an important regulator of serum cholesterol which may have implications for the development of both hypertension and obesity. In this study, genotypes for a low density lipoprotein receptor gene (LDLR) dinucleotide polymorphism were determined in both lean and obese normotensive populations.

2. In previous cross‐sectional association studies an Apa LI and a Hinc II polymorphism for LDLR were shown to be associated with obesity in essential hypertensives. However, these polymorphisms did not show an association with obesity in normotensives.

3. In contrast, this study reports that preliminary results for an LDLR microsatellite marker, located more towards the 3’ end of the gene, show a significant association with obesity in the normotensive population studied. These results indicate that LDLR could play an important role in the development of obesity, which might be independent of hypertension.
AUGMENTED ENDOGENOUS NITRIC OXIDE PRODUCTION IN PARTIAL PORTAL VEIN‐LIGATED RATS
Authors: Hori Naoki , Takahashi Hakuo , Okanoue Takeshi , Sawa Yoshihiko , Mori Takashi , Takami Shiro , Yoshimura Manabu , Kashima Kei
Published: June 2007

1. Endothelium‐derived nitric oxide (NO) is a potent vasodilator. Because the body oxidizes it to nitrate ions, NO3‐, measurement of the serum concentration and the urinary excretion of NO3‐ may be an index for endogenous NO. We investigated the role of NO on hyperdynamic circulation in cirrhotic and partial portal vein‐ligated rats by measuring NO3.

2. Liver cirrhosis was induced by administration of thioacetamide. Systemic and splanchnic haemodynamics and splenic‐systemic shunting were determined by tracer microspheres. The concentration of NO3‐ was measured by using high‐performance liquid chromatography with an anion‐column.

3. We found that systemic and splanchnic hyperdynamic circulation existed to almost the same extent in cirrhotic and in portal vein‐ligated rats as compared to the controls and sham‐operated rats, respectively. Splenic‐systemic shunting was markedly greater in portal vein‐ligated rats than in cirrhotic rats.

4. Serum NO3‐ levels and urinary excretion of NO3‐ in cirrhotic rats tended to increase as compared to the controls. On the other hand, the levels in portal vein‐ligated rats were significantly increased as compared to those of the sham‐operated rats, and were significantly and negatively correlated to the splanchnic arterial resistance and total vascular resistance. The amount of urinary excretion of NO3‐ significantly correlated to splenic‐systemic shunting (r = 0.61, P<0.05) only in portal vein‐ligated rats.

5. We suggest that these high levels of NO3‐ in portal vein‐ligated rats relate to the extensive formation of porto‐collateral vasculature or acute changes in systemic and splanchnic haemodynamics due to portal vein‐ligation.
EFFECT OF RENAL NERVE DENERVATION ON TISSUE CATECHOLAMINE CONTENT IN SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Yoshida Makoto , Yoshida Emiko , Satoh Susumu
Published: June 2007

1. To clarify the possible role of tissue catecholamines in the development of hypertension, we investigated the effect of bilateral renal denervation on the catecholamine contents of central and peripheral tissues in spontaneously hypertensive rats (SHR).

2. Norepinephrine (NE) content in renal cortex, renal medulla, and adrenal gland was higher in 7 week old SHR than age‐matched Wistar‐Kyoto rats (WKY). Dopamine (DA) content in the brainstem and hypothalamus was also higher in SHR, but NE and epinephrine (EPI) content in these areas were not different between strains. Similar differences in catecholamines were observed in 9 week old rats in which a sham operation of bilateral renal denervation was performed 2 weeks previously.

3. Bilateral renal denervation produced an almost complete reduction of NE content in the kidney in both strains and prevented the development of hypertension. DA content in the brainstem was also decreased by renal denervation in SHR but not in WKY. NE and EPI content in central tissues were not affected by renal denervation.

4. These results suggest that DA content in brainstem area, as well as NE content in the kidney, have a relationship in the development of hypertension in SHR.
REPAIR AND RECOVERY FOLLOWING SPINAL CORD INJURY IN A NEONATAL MARSUPIAL (MONODELPHIS DOMESTICA)
Authors: Saunders N. R. , Deal A. , Knott G. W. , Varga Z. M. , Nicholls J. G.
Published: June 2007

1. Repair and recovery following spinal cord injury (complete spinal cord crush) has been studied in vitro in neonatal opossum (Monodelphis domestica), fetal rat and in vivo in neonatal opossum.

2. Crush injury of the cultured spinal cord of isolated entire central nervous system (CNS) of neonatal opossum (P4–10) or fetal rats (E15–E16) was followed by profuse growth of fibres and recovery of conduction of impulses through the crush. Previous studies of injured immature mammalian spinal cord have described fibre growth occurring only around the lesion, unless implanted with fetal CNS.

3. The period during which successful growth occurred in response to a crush is developmentally regulated. No such growth was obtained after P12 in spinal cords crushed in vitro at the level of C7–8.

4. In vivo, in the neonatal (P4–8) marsupial opossum, growth of fibres through, and restoration of, impulse conduction across the crush was apparent 1–2 weeks after injury. With longer periods of time after crushing a considerable degree of normal locomotor function developed.

5. By the time the operated animals reached adulthood, the morphological structure of the spinal cord, both in the region of the crush and on either side of the site of the lesion, appeared grossly normal.

6. The results are discussed in relation to the eventual longterm possibility of devising effective treatments for patients with spinal cord injuries.
EFFECTS OF A CONTINUOUS INFUSION OF DOPAMINE ON THE VENTILATORY AND CAROTID BODY RESPONSES TO HYPOXIA IN CATS
Authors: Ide Tohru , Shirahata Machiko , Chou Chung‐Long , Fitzgerald Robert S.
Published: June 2007

1. We investigated how a continuous infusion of dopamine (DA; 5μg/kg per min), which is often used clinically, would affect the ventilation and carotid chemoreceptor neural activity in anaesthetized cats.

2. In anaesthetized, spontaneously breathing cats, tidal volume (Vt) and respiratory frequency (f) were continuously monitored at five levels of inspired oxygen (P102= 110,130, 150, 170, 760mmHg) during Da or saline infusion. Vt and f were sampled for 1 min after 3 min exposure to each level of P102. Time control study was also performed.

3. DA infusion significantly lowered VT under both normoxia and hypoxia in seven of eight cats. Respiratory frequency was not affected by DA infusion. Depression of ventilation during post‐hypoxic hyperoxia was augmented by DA infusion. Chemodenervntion abolished the ventilatory response to hypoxia and DA did not further affect the ventilatory response to hypoxia.

4. In a second group of artificially ventilated cats, carotid chemoreceptor neural activity was recorded at five levels of arterial oxygen tension. DA infusion significantly depressed carotid chemoreceptor neural activity during normoxia and hypoxia in six of seven cats.

5. These findings suggest that changes in ventilation during low dosage of DA infusion closely correlate with carotid body neural output. A predominant effect of this dosage of DA (5 μg/kg per min) was depression in the ventilatory response to hypoxia due to an inhibition of carotid body neural output.
α1‐ADRENOCEPTORS ON RABBIT AORTIC SMOOTH MUSCLE CELLS IN CULTURE AND IN EXPERIMENTAL INTIMAL THICKENING
Authors: Manderson John A. , Hayward Ian P. , Pak Elena , Horrigan Sophie , Hanley Glenys E. , Stephenson Jennifer A. , Brown Lindsay , Campbell Julie H. , Campbell Gordon R.
Published: June 2007

1. This study has defined α1‐adrenoceptors and their reactivity in rabbit aorta, following removal of the endothelium and formation of a myointimal thickening, and also in smooth muscle cells (SMC) in cell culture which had undergone serial passaging and changes in phenotype.

2. [3H]‐prazosin binding to SMC from control aorta, vessels 2 weeks after endothelial denudation and sub‐cultured SMC (passage 3–6) was specific (displaceable with 10 μmol/L phentolamine), and of high affinity to a single class of sites (Kd range: 71–114 pmol/L). The maximum binding density (Bmax) of α1‐adrenoceptors on SMC from the neointima (11105 ± 771 sites/cell) was not significantly different to that of control medial SMC (14014 ± 2472 sites/cell). However, SMC cultured to passage 6, showed a 2‐fold increase in Bmax (30227 ± 4349 sites/cell).

3. The production of inositol phosphates (IP1, IP2 and IP3) by SMC following 10μmol/L phenylephrine was assayed. Both freshly‐dispersed aortic SMC and sub‐cultured SMC were stimulated to produce increased inositol phosphates by the addition of phenylephrine which was completely inhibited by pre‐incubation with 10 μmol/L phentolamine, suggesting that the stimulation was via α1‐adrenoceptors.

4. Maximal contractile responses of isolated thoracic and abdominal aortic rings to KCl (100 mmol/L), 5‐HT and phenylephrine were unchanged two weeks after endothelial denudation. However, phenylephrine was significantly less potent (2.7‐fold) in both areas of the aorta, while the potency of 5‐HT was significantly enhanced (2.7‐fold) after endothelial denudation only in the abdominal aorta.

5. The decreased sensitivity of the rabbit aorta to α1‐adrenoceptor agonists following endothelial denudation and the formation of a myointimal thickening is not due to changes in affinity or density of α1‐adrenoceptors. However multiple passaging of SMC in culture leads to an increase in α1‐adrenoceptor density. This change can be related to the altered cytodifferentiation of irreversible synthetic state SMC which are similar to those in atherosclerotic lesions.
ROLE OF INTRACELLULAR SIGNALLING PATHWAYS IN HYDROGEN PEROXIDE‐INDUCED INJURY TO RAT GLOMERULAR MESANGIAL CELLS
Authors: Shaw Sidney , Naegeli Patricia , Etter Jean‐Daniel , Weidmann Peter
Published: June 2007

1. Brief exposure of cultured rat glomerular mesangial cells (GMC) to H202 in nominally bicarbonate‐free solution induced a rapid dose dependent, dantrolene‐inhibitable increase in intracellular free Ca2+ from 65 ± 6 to 203 ± 14 nmol/L and a prolonged release of [14C]‐arachidonic acid [14C]‐AA which preceded the onset of cell membrane damage assessed by trypan‐blue uptake.

2. Ca2+ responses were potentiated in HCO3−/CO2 containing buffers and reached values of 1145 ± 100 nmol/L at 1 mmol/L H2O2. In HCO3−/CO2 solutions, but not HEPES buffer, HzOz‐induced Ca2+ increases were markedly attenuated by verapamil (100 μmol/L) or removal of extracellular calcium.

3. Enhanced release of [14C]‐AA was partially attenuated by inhibitors of key intracellular signalling mechanisms including the phospholipase‐A2 (PLA2) inhibitor mepacrine (100 μmol/L), the NADPH oxidase inhibitor diphenyliodonium (10 μmol/L), the mitochondrial calcium‐cycling inhibitor ruthenium red (100 μmol/L) and the iron chelator dipyridyl (100 μmol/L). Release was unaffected by protein kinase C inhibition with H7 (100 μmol/L), inositol triphosphate antagonism with neomycin (1 mmol/L) or overnight treatment with the G‐protein antagonist pertussis toxin (5 μg/mL).

4. Several structurally diverse lipoxygenase inhibitors, including esculetin, baicalein and phenidone, over the dose range 1–100 μmol/L, also prevented [14C]‐AA release and markedly protected against cell membrane damage. No drug directly scavenged H202 assessed by UV absorption.

5. These results indicate that H2O2 activates in GMC a complex series of interrelated pathological mechanisms which in turn contribute to a prolongation of oxidative damage beyond the time of the initial exposure. These include an increase in intracellular calcium which, depending upon conditions, appears to be mediated by release from intracellular stores as well as Ca2+ entry from the extracellular space. In turn there is a sustained release of arachidonic acid, which may partly depend on prolonged activation of PLA2 but not phospholipase C.

6. Release of [14C]‐AA could be attenuated by inhibitors of NADPH oxidase, mitochondrial calcium‐cycling, iron chelators and a structurally diverse range of lipoxygenase inhibitors in association with protection from H2Otrnediated cell membrane damage.
PROTON AND POTASSIUM TRANSPORT BY H+/K+‐ATPases
Authors: van Driel Ian R. , Callaghan Judy M.
Published: June 2007

1. H+/K+‐ATPases are members of the P‐type ATPase multigene family. The prototypical H+/K+‐ATPase is the protein that acidifies gastric luminal contents. The physiological and pharmacological significance of this pump has led to a detailed investigation of its biochemistry and molecular and cell biology.

2. Recently, a number of closely related H+/K+‐ATPase isoforms have been discovered. These isoforms are present in organs other than the stomach, including the colon and kidney, where they contribute to acid—base and potassium homeostasis. The structure, expression and physiological roles of the gastric H+/K+‐ATPase and other isoforms are reviewed.
NOVEL MUTATION IN THE FIRST INTRON OF THE SPONTANEOUSLY HYPERTENSIVE RAT RENIN GENE UPSTREAM OF THE TANDEM REPEAT ELEMENT
Authors: Di Nicolantonio R. , Yu H. , Wilks A. , Lan L.
Published: June 2007

1. The first 1100 base pairs of the first intron of the renin gene was amplified from the spontaneously hypertensive rat (SHR), Wistar‐Kyoto (WKY) and Sprague‐Dawley (SD) rats. A Bgl II restriction fragment length polymorphism (RFLP) was identified in this region of the SHR renin gene.

2. Sequence analysis located the Bgl II RFLP between positions 500 and 505 of the reported rat renin gene. The new Bgl II cut site was produced by a single base mutation from G to A.

3. Whether this mutation in the first intron of the SHR renin gene plays a role in the reported overexpression of the renin gene in this strain remains to be elucidated.
PLATELET‐DERIVED GROWTH FACTOR B‐CHAIN COMPRISES THE MAJOR PART OF ENHANCED RELEASED MITOGEN FROM AORTIC ENDOTHELIAL CELLS OF STROKE‐PRONE SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Sasahara M. , Hayase Y. , Yang X. H. , Iihara K. , Amano S. , Hazama F.
Published: June 2007

1. The present study was conducted to analyse the release and production of mitogen in cultured aortic endothelial cells of stroke‐prone spontaneously hypertensive rats (SHRSP), for the further understanding of the role of arterial endothelial cells in the genesis of vascular lesions in hypertension.

2. The cultured aortic endothelial cells derived from SHRSP increased released mitogens were compared with those from control Wistar‐Kyoto rats (WKY) with respect to cultured vascular medial smooth muscle cells and fibroblasts.

3. Biochemical analyses determined that the major part of mitogen released from aortic endothelial cells of both SHRSP and controls was the platelet‐derived growth factor B‐chain.

4. Further northern analyses revealed that the transcripts of PDGF B‐chain were constitutively accumulated three‐ to fourfold in quiescent aortic endothelial cells from SHRSP, compared with those from WKY through passages 2 to 5.

5. However, the half‐lives of the transcripts after actinomy cin D treatment were 1.12 h (s.d. = 0.14,n= 4) and 1.28 h (s.d. = 0.08,n= 3), in SHRSP and in WKY, respectively, showing no significant difference.

6. These suggest that the increased accumulated transcripts of PDGF B‐chain in SHRSP are due to an enhanced trans‐criptional rate. These enhanced release and production of PDGF‐B chain in arterial endothelial cells, which may be induced under chronic hypertensive conditions, is suggested to contribute to the genesis of vascular lesion in hypertension, through the stimulation of vascular smooth muscle cell proliferation and hypertrophy.
OCULAR FUNDUS CHANGES IN MALIGNANT OR PRECOCIOUS STROKE‐PRONE SPONTANEOUSLY HYPERTENSIVE RATS AFTER ADMINISTRATION OF ANTIHYPERTENSIVE DRUGS
Authors: Hamada Yoh , Niisato Etsurou , Otor Toshifumi , Chikugo Taka‐aki , Ohta Yoshio , Suzuki Tsuneyuki , Okamoto Kozo
Published: June 2007

1. Malignant or precocious stroke‐prone spontaneously hypertensive rats (M‐SHRSP) showed hypertensive ocular fundus changes with severe hypertension, but various anti‐hypertensive drugs given over a proper period improved funduscopic findings.

2. We treated a M‐SHRSP with SQ29, 852 (an angiotensin converting enzyme inhibitor, ACEI) or manidipine (a calcium antagonist) and observed hypertensive vascular changes in the fundus.

3. The M‐SHRSP treated with anti‐hypertensive drugs lived longer and the hypertensive fundic changes improved in both groups. But there were some differences of histochemical staining reaction on the endothelial cell‐surface and mucopoly‐saccharides accumulations between the treated group of ACEI and the group treated with the calcium antagonist.

4. In the treated group with calcium antagonist, the anionic ion functions of the endothelial cell‐surface were impaired and organic retinal or choroidal damages appeared to have deteriorated.
ROLE OF NITRIC OXIDE IN THE CONTROL OF BLOOD PRESSURE IN YOUNG AND ADULT SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Akiba Y. , Yamaguchi N. , Amano H. , Fujii T. , Fujimoto K. , Suzuki T. , Kawashima K.
Published: June 2007

1. The depressor response to sodium nitroprusside (SNP) and the pressor response to Nω‐nitro‐L‐arginine methyl ester (L‐NAME) were investigated in anaesthetized and ganglion‐blocked 6 week old (young) and 20 week old (adult) spontaneously hypertensive rats (SHR), and the results were compared with those in age‐matched normotensive Wistar‐Kyoto (WKY) rats.

2. SNP produced a dose‐dependent decrease of the mean blood pressure (BP) in both strains, and no differences in vascular sensitivity to SNP were observed between the strains.

3. L‐NAME caused dose‐dependent pressor responses in both strains. The sensitivity and the maximal response to L‐NAME in SHR were significantly greater than those in age‐matched WKY (P < 0.05 or 0.01; t‐test, 13d.f. in both ages). However, there were no significant differences in the responses between ages in each strain.

4. Acute reduction of BP induced by 7‐O‐ethylfangchinoline did not affect the responses to SNP and L‐NAME in the adult SHR.

5. These results indicate that a greater amount of NO is tonically released in SHR and that its contribution to BP control is greater in SHR than in WKY, whereas vascular sensitivity to NO does not differ between the strains. In addition, acute changes in BP do not affect the degree of dependency on NO for BP control.
PROMOTION OF NITRIC OXIDE FORMATION BY HEPARIN IN CULTURED AORTIC ENDOTHELIAL CELLS FROM SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Minami M. , Yokokawa K. , Kohno M. , Ikeda M. , Horio T. , Kano H. , Hanehira T. , Yasunari K. , Takeda T.
Published: June 2007

1. The present study examined the effect of heparin on nitric oxide (NO) formation and cyclic guanosine 3′, 5′‐monophos‐phate (cGMP) levels in cultured aortic endothelial cells (EC) from spontaneously hypertensive rats (SHR) and normoten‐sive Wistar‐Kyoto (WKY) rats.

2. Bradykinin (BK), adenosine diphosphate (ADP), Ca2+ ionophore A23187 (Io) and endothelin‐3 (ET‐3) stimulated the production of NO and cGMP. No significant difference was observed in both NO and cGMP production in EC between WKY and SHR.

3. Heparin enhanced BK‐, ADP‐, Io‐ and ET‐3–stimulated NO and cGMP production. These enhancements by heparin in EC were significantly greater in SHR than in WKY.

4. Both NO formation and cGMP production stimulated by the agonists and/or heparin were blocked in the presence of NG‐monomethyl‐L‐arginine (LNMMA, 10‐5mol/L).

5. Increased sulphur level was observed on heparin‐treated SHR EC surface compared with that on control SHR EC or on heparin‐treated WKY EC surface.

6. These results suggest that heparin promotes agonist‐induced NO‐cGMP response in cultured EC from SHR.
CHANGES OF ENDOTHELIAL FUNCTIONS IN THE CORONARY ARTERY AFTER CHRONIC NITROARGININE FEEDING
Authors: Kajimoto Noriyoshi , Ogawa Hiroshi , Suzuki Aritomo
Published: June 2007

1. The effects of chronic NG‐nitro‐L‐arginine (LNA) feeding on the endothelial function in isolated coronary arteries from stroke‐prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar‐Kyoto (WKY) rats were studied.

2. A diet containing LNA (0.02%) was given to male SHRSP and WKY at 6 weeks of age and the coronary arteries were dissected on the 10th day of feeding.

3. In the SHRSP and WKY fed the LNA‐free diet, acetyl‐choline (ACh) relaxed the precontracted ring segments of the coronary artery with intact endothelium in a dose‐dependent manner. The reactivity was stronger in the WKY than in the SHRSP. However, the ACh‐induced relaxation after the LNA‐feeding was significantly stronger in the coronary arteries from the WKY than in those from the SHRSP.

4. The relaxation induced by the calcitonin gene‐related peptide (CGRP) was endothelium‐dependent and endothelium‐independent. The degree of the response in the rats fed the LNA‐containing diet was not significantly different from that in the rats fed the LNA‐free diet.

5. The vasodilator response induced by sodium nitroprusside (SNP) was dose‐dependent and similar in the rats fed the LNA containing diet and the LNA‐free diet.

6. These findings indicate that chronic LNA feeding markedly impaired the endothelial nitric oxide formation in the coronary artery from young SHRSP.
REGIONAL DISTRIBUTION OF SUPEROXIDE DISMUTASE IN THE BRAIN AND MYOCARDIUM OF THE STROKE‐PRONE SPONTANEOUSLY HYPERTENSIVE RAT
Authors: Kimoto S. , Nishida S. , Funasaka K. , Nakano T. , Teramoto K. , Tomura T. T.
Published: June 2007

1. Enzyme activities and contents of manganese and copperzinc superoxide dismutase (Mn‐, Cu/Zn‐SOD) and oxygen free‐radical scavengers were determined in the myocardium (right, left ventricle) and brain (cerebral cortex, hippocampus) of 15 and 31 week old stroke‐prone spontaneously hypertensive rats (SHRSP).

2. In 15 week old SHRSP myocardium, both Mn‐ and Cu/Zn‐SOD activities were higher but in 31 week old SHRSP, these were lower than that in Wistar‐Kyoto (WKY) rats. Further, correlation between Mn‐SOD content and activity in 31 week old SHRSP myocardium showed that specific activity was lower than that in WKY.

3. In 15 and 31 week old SHRSP cerebral cortex and hippocampus, SOD content and activity showed a tendency to be lower than that in WKY.

4. These results indicate that enzymatically inactive or low‐active Mn‐SOD protein exists in SHRSP myocardium, and that the alteration of SOD may be one of the causative factors for the vulnerability of the myocardium and brain against O2‐radicals.
RELATIONSHIP BETWEEN ERYTHROCYTES GLUTATHIONE PEROXIDASE AND INCIDENCE OF STROKE LESION IN THE STROKE‐PRONE SPONTANEOUSLY HYPERTENSIVE RAT
Authors: Murakami Tetsuo , Takemori Kumiko , Takeda Tohru , Yoshizumi Hajime
Published: June 2007

1. To determine biochemically the incipient timing of cerebral stroke in stroke‐prone spontaneously hypertensive rats (SHRSP) the relation between the glutathione peroxidase (GSH‐Px) activity in erythrocytes and the extent of stroke lesion was investigated.

2. When the blood pressure of SHRSP was maintained over 250 mmHg, the GSH‐Px activity was lowered and the body‐weight also decreased. In the SHRSP where the GSH‐Px activity in erythrocytes dropped below 23 units/mL blood, the incidence of cerebral stroke was 98% (n= 88/90).

3. The haemoglobin and haematocrit level were unchanged even after the GSH‐Px activity dropped to 23 units/mL blood.

4. Lowering of GSH‐Px activity in erythrocytes observed during continued hypertension was found to be due to decreased GSH‐Px protein, but not to an inactivation of enzymes, as evidenced from immunochemical titration.

5. Lowering of GSH‐Px activity in erythrocytes was found to be closely related with the incidence of cerebral stroke in SHRSP. These findings suggest that tracing of the GSH‐Px activity in erythrocytes in SHRSP may serve as an indicator for prediction and prognosis of stroke lesion.
ALTERNATIVE SPLICING OF NATRIURETIC PEPTIDE A AND B RECEPTOR TRANSCRIPTS IN THE RAT BRAIN
Authors: Francoeur F. , Gossard F. , Hamet P. , Tremblay J.
Published: June 2007

1. In the present study we searched for variants of alternative splicing of guanylyl cyclase A and B mRNA in rats in vivo.

2. Guanylyl cyclase A2 and guanylyl cyclase B2 isoforms of guanylyl cyclase produced by alternative splicing leading to the deletion of exon 9 of both transcripts were quantified in several rat organs.

3. Only one alternative splicing was found in the regulatory domain, encoded by exons 8–15.

4. Quantification of the guanylyl cyclase B2 isoform in different rat organs and in cultured aortic smooth muscle cells showed that this alternative splicing was tissue‐specific and occurred predominantly in the central nervous system where the alternatively spliced variant represented more than 50% of the guanylyl cyclase B mRNA.

5. The same alternative splicing existed for guanylyl cyclase A mRNA but at very low levels in the organs studied.

6. Alternative splicing of guanylyl cyclase B exon 9 in the brain may play an important role in signal transduction, since the expressed protein possesses a constitutionally active guanylyl cyclase acting independently of C‐type natriuretic peptide regulation.
ALTERED GENE EXPRESSION OF NATRIURETIC PEPTIDE RECEPTOR SUBTYPES IN THE KIDNEY OF STROKE‐PRONE SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Goto Masahisa , Itoh Hiroshi , Tanaka Issei , Suga Shin‐ichi , Ogawa Yoshihiro , Kishimoto Ichiro , Nakagawa Masayo , Sugawara Akira , Yoshimasa Takaaki , Mukoyama Masashi , Nakao Kazuwa
Published: June 2007

1. To elucidate the physiological and pathophysiological role of the natriuretic peptide system in the progression of hypertensive renal disease, we examined the gene expression of natriuretic peptide receptor subtypes, guanylate cyclase‐A (GC‐A), guanylate cyclase‐B (GC‐B) and clearance receptor (C receptor), in the kidney of stroke‐prone spontaneously hypertensive rats (SHRSP) at 8 and 20 weeks of age, and compared them with their gene expression in age‐matched Wistar‐Kyoto (WKY) rats.

2. Northern blot analyses revealed that messages for three natriuretic peptide receptor subtypes were expressed in the kidney, and their expressions were higher in the glomeruli than in the whole kidney in each strain.

3. In 20 week old rats with established hypertension, the glomerular concentration of GC‐A mRNA was significantly higher in SHRSP than in WKY. The concentrations of GC‐B and C receptor mRNA in the glomeruli tended to increase and decrease, respectively, but they were not statistically significant in SHRSP.

4. In 8 week old rats, the glomerular concentrations of GC‐A, GC‐B and C receptor mRNA were not significantly different between SHRSP and WKY.

5. This study demonstrates that in the progression of hypertension, the expression of GC‐A, which mediates biological actions of natriuretic peptides, is enhanced in the kidney of SHRSP compared to that of WKY. Together with the augmented secretion of the ligands previously revealed, altered expression of natriuretic peptide receptor subtypes in SHRSP may have a deterrent role in the development of hypertension and its renal complications.
PREPARATION OF A MONOCLONAL ANTIBODY AGAINST MOUSE BRAIN NATRIURETIC PEPTIDE (BNP) AND TISSUE DISTRIBUTION OF BNP IN MICE
Authors: Nakagawa Masayo , Tanaka Issei , Suga Shin‐ichi , Ogawa Yoshihiro , Tamura Naohisa , Goto Masahisa , Sugawara Akira , Yoshimasa Takaaki , Itoh Hiroshi , Mukoyama Masashi , Nakao Kazuwa
Published: June 2007

1. In order to explore the significance of brain natriuretic peptide (BNP), a cardiac hormone secreted from the ventricle, in mice, we prepared a monoclonal antibody against mouse BNP (mBNP) and established a specific radioimmunoassay (RIA) for mBNP.

2. A monoclonal antibody, KY‐mBNP‐I, was prepared by the fusion of mouse myeloma cells X63‐Ag8.653 with spleen cells of the BALB/c mouse immunized with synthetic mBNP[108–121] conjugated to bovine thyroglobulin. KY‐mBNP‐I belonged to an IgG2a subclass and showed a high affinity for mBNP(Ka = 1.8 × 1011 mol/L−l).

3. The RIA established that using KY‐mBNP‐I was highly sensitive and specific for mBNP, with an IC50 value of 3 fmol/ tube and cross‐reactivities of less than 0.003% with related natriuretic peptides. mBNP‐like immunoreactivity (mBNP‐LI) was detected in the mouse atrium (0.35 ± 0.02 nmol/g), ventricle (20.5 ± 0.5 pmol/g) and kidney (0.50 ± 0.05 pmol/g), but not in other tissues including brain.

4. Gel filtration analysis revealed that the major component of tissue mBNP‐LI was co‐eluted with synthetic mBNP[77–1211, a 45‐amino acid mature peptide.

5. The monoclonal antibody and RIA for mBNP established here will provide useful tools to investigate the functional significance of BNP in mice, coupled with the genetic engineering approach.
ENDOTHELIN‐1 GENE EXPRESSION AND VASCULAR HYPERTROPHY IN DOCA‐SALT HYPERTENSION COMPARED TO SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Schiffrin Ernesto L. , Larivière Richard , Li Jin‐Sheng , Sventek Pavol , Touyz Rhian M.
Published: June 2007

1. Enhanced endothelin‐1 gene expression has been found in blood vessels of deoxycorticosterone acetate (DOCA)‐salt hypertensive rats. In this study, the effects of salt, DOCA and the development of hypertension in DOCA‐salt hypertensive rats on the expression of the endothelin‐1 gene in blood vessels and on vascular hypertrophy were compared in Sprague‐Dawley (SD) rats and spontaneously hypertensive rats (SHR).

2. Increased endothelin‐1 mRNA was found by northern blot analysis in the mesenteric arterial bed of DOCA‐salt hypertensive rats and DOCA‐salt SHR, but not in DOCA or salt‐treated SD rats or in SHR, even when blood pressure reached a mean of 211 mmHg in DOCA‐treated SHR.

3. Vascular structure was studied in small mesenteric arteries mounted on a wire myograph. The media width to lumen diameter ratio showed a close correlation with systolic blood pressure except in DOCA‐salt hypertensive rats and DOCA‐salt SHR, in which it was greater than accounted for by the level of blood pressure. Treatment of DOCA‐salt hypertensive rats with the combined ETA/ETB endothelin antagonist bosentan lowered blood pressure slightly, but vascular hypertrophy regressed almost completely and any hypertrophy remaining could be explained by the residual elevated blood pressure.

4. In conclusion, SHR do not exhibit enhanced expression of endothelin‐1 in blood vessels. DOCA, salt and elevated blood pressure interact to induce increased arterial expression of endothelin‐1. Vascular overexpression of the endothelin‐1 gene may produce vascular hypertrophy independently of blood pressure elevation.
URINARY EXCRETION OF 19‐NORALDOSTERONE IN THE SPONTANEOUSLY HYPERTENSIVE RAT AND STROKE‐PRONE SPONTANEOUSLY HYPERTENSIVE RAT
Authors: Takeda Yoshiyu , Miyamori Isamu , Yoneda Takashi , Hurukawa Kenji , Inaba Satoru , Ito Yuji , Takeda Ryoyu
Published: June 2007

1. We measured the urinary excretion of 19‐noraldosterone in the spontaneously hypertensive rat (SHR) and stroke‐prone SHR (SHRSP) during the development of hypertension and compared these measurements with Wistar‐Kyoto (WKY) rats.

2. 19‐Noraldosterone in rat urine was confirmed using HPLC‐MS. Urine samples were collected from 4 and 9 week old SHR (n= 12), SHRSP (n= 12) and WKY rats (n= 9). 19‐Noraldosterone was measured by specific radio immunoassay after purification of the urine extracts with HPLC.

3. There were no significant differences in plasma corticosterone among SHR, SHRSP and WKY rats at 4 and 9 weeks of age. Aldosterone levels were increased in the prehypertensive SHR and SHRSP. Nine week old SHRSP showed high plasma concentration of aldosterone compared with SHR or WKY rats of the same age.

4. Urinary excretion of 19‐noraldosterone was increased in 4 week old SHR (15 ± 4.2 pmol/day) and SHRSP (17 ± 5.0 pmol/day) compared with WKY rats (9 ± 3.9 pmol/day) at the same age. Nine week old SHR showed decreased urinary excretion of 19‐noraldosterone compared with WKY rats at the same age. Urinary levels of 19‐noraldosterone were higher in SHRSP (11 ± 4.9 pmol/day) than in SHR (7 ± 4.0 pmol/day) at 9 weeks of age.

5. Adrenal mineralocorticoids are suggested to be responsible for the abnormal vascular reactivity observed in SHRSP. Relatively elevated levels of 19‐noraldosterone in SHRSP may contribute to malignant hypertension in this model.
LIPID MEDIATORS AND PROTEIN KINASE C FOR INTRACELLULAR SIGNALLING
Authors: Nishizuka Yasutomi , Nakamura Shun‐ichi
Published: June 2007

1. The stimulation of a cell surface receptor initiates a degradation cascade of various membrane lipid constituents.

2. Many of their metabolites have potentials to induce, intensify and prolong the activation of protein kinase C that is needed for sustained cellular responses.
INCREASED CALCIUM SEQUESTRATION BY SARCOPLASMIC RETICULUM IN SMALL MUSCULAR ARTERIES IN YOUNG SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Toyoda Yasuaki , Shima Hiroki , Sasajima Hisashi , Nishio Ichiro
Published: June 2007

1. Sarcoplasmic reticulum (SR) in small resistance arteries plays a role in the regulation of the cytosolic free calcium concentration by sequestration of calcium from cytoplasm.

2. To examine the contribution of calcium (Ca2+) sequestration by the SHR to both contraction and relaxation in young spontaneously hypertensive rats (SHR), we measured evoked tension before and after depletion of SR Ca2+ stores in the rings of the first branch of superior mesenteric artery in 5 week old SHR and age‐matched Wistar‐Kyoto (WKY) rats. Contractile responses were induced by 40 mmol/L potassium and 10 mmol/L caffeine before and after the treatment with ryanodine or thapsigargin, which depletes SR calcium stores.

3. The magnitude of potassium‐induced contraction was almost the same in both strains.

4. Ryanodine and thapsigargin did not affect the resting tension and almost decreased caffeine‐induced contraction in both strains.

5. After the treatment with ryanodine or thapsigargin, the magnitude and the rate of potassium‐induced contraction were augmented greatly in SHR, but not in WKY.

6. The relative relaxation rate after exposure of potassium was significantly slowed in SHR by ryanodine or thapsigargin, but only slightly in WKY.

7. These results suggest that Ca2+ sequestration by the SR in SHR was greater than in WKY. Therefore, it is concluded that SR plays an important role in preventing the development of hypertension in SHR via a buffering effect on the elevation of cytosolic free Ca2+.
EXPRESSION OF SARCOPLASMIC RETICULUM Ca2+‐ATPase mRNA IN THE HYPERTROPHIED HEART OF YOUNG SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Ohta Kensuke , Kim Shokei , Hamaguchi Akinori , Miura Katsuyuki , Yukimura Tokihito , Iwao Hiroshi
Published: June 2007

1. Recent evidence indicates that cardiac hypertrophy induced by pressure overload is associated with a decrease in sarcoplasmic reticulum (SR) Ca2+‐ATPase of myocytes, which may contribute to a diastolic dysfunction of the heart by causing intracellular Ca2+ overload. To elucidate whether or not this is also the case in genetic hypertension, we examined cardiac mRNA levels of SR Ca2+‐ATPase in 11 week old spontaneously hypertensive rats (SHR) by northern blot analysis.

2. Furthermore, to test the effects of short‐term inhibition of the renin‐angiotensin system on its expression, we treated 10 week old SHR with angiotensin‐converting enzyme inhibitors (alacepril and imidapril) or an AT1 receptor antagonist (SC‐52458) for 7 days.

3. Though the left ventricular weight of SHR was significantly higher than that of Wistar‐Kyoto (WKY) rats (277 ± 6 vs 237 ± 4mg/100g bodyweight, respectively, P < 0.05), the level of SR Ca2+‐ATPase mRNA showed no difference between SHR and WKY at this age.

4. Moreover, the aforementioned three drugs did not at all affect the SR Ca2+‐ATPase expression of SHR.

5. Thus, the expression of SR Ca2+‐ATPase was not down‐regulated in the heart of 11 week old SHR, and seemed not to be mediated by angiotensin AT1 receptor at this age. Since some evidence on pressure‐overloaded cardiac hypertrophy indicate that the decrease in SR Ca2+‐ATPase expression occur in prominent hypertrophy and in the failured heart, further studies on cardiac SR Ca2+‐ATPase expression in more aged SHR will be required.