bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECT OF OVINE PROLACTIN ON THE EPIDIDYMAL SIALIC ACID CONCENTRATION IN MALE RATS
Authors: Gautam Rajeev , Pereira Ben M. J. 
Published: June 2007

SUMMARY1. Previous experiments have shown that the level of sialic acid in the epididymis is influenced by factors originating in the testis.2. To exclude interference from these factors, both orchidectomized and duct‐ligated rats were used to study the potential role of prolactin in the epididymis.3. When ovine prolactin was injected in orchidectomized rats, a dose‐related increase in the level of sialic acid was observed in the epididymis.4. That this action of prolactin is independent of androgen was confirmed by studies using bromocryptine, which decreases circulating endogenous prolactin.5. The physiological role(s) of epididymal sialic acid production in response to prolactin remain to be established.
AGEING HAS NO EFFECT ON THE VOLUME DENSITY OF HEPATOCYTES, RETICULOENDOTHELIAL CELLS OR THE EXTRACELLULAR SPACE IN LIVERS OF FEMALE SPRAGUE‐DAWLEY RATS
Authors: Martin G. , Sewell R. B. , Yeomans N. D. , Smallwood R. A. 
Published: June 2007

SUMMARY1. The hepatic reticuloendothelial cell population is generally assumed to increase in size, along with the liver, during ageing in rats. However, this has not been rigorously established.2. Using electron microscopy and stereological techniques, the present study has shown that the volume densities of hepatocytes and Kupffer cells (and probably also of endothelial cells, fat storing cells and the extracellular space) of the livers of female Sprague‐Dawley rats are the same at 2 and 24–25 months of age.3. This result indicates that the increase in size of the liver during ageing in the rat is associated with an equivalent increase in the volume of each cell population and the extracellular space.
ATRIAL NATRIURETIC PEPTIDE IN PREGNANCY: RESPONSE TO ORAL SODIUM SUPPLEMENTATION
Authors: Lowe Sandra A. , Macdonald Graham J. , Brown Mark A. 
Published: June 2007

SUMMARY1. The control of extracellular fluid volume (ECFV) in normal pregnancy may be related to changes in atrial natriuretic peptide. Previous studies in non‐pregnant subjects have suggested that plasma atrial natriuretic peptide (ANP) increases in response to dietary sodium supplementation because of an increase in plasma volume, although this has not been measured directly.2. Nine women who were pregnant in the third trimester undertook oral sodium supplementation (136 mmol) for 5 days in addition to their usual diet. Twenty‐four hour urinary sodium excretion increased by 125 ± 54 mmol/day (mean ±s.d.; P < 0.01). Plasma volume was unchanged, although total ECFV tended to increase (P < 0.09 and bodyweight increased (1.3 ± 1.4 kg; P < 0.01) at the end of these diets.3. Plasma ANP increased by 30.7 [8.6, 34.5] pmol/L (median [25th, 75th percentile]; P < 0.05), while plasma renin concentration decreased significantly from 7.3 [6.2, 11.2] to 2.6 [1.7, 3.9] pmol angiotensin I/mL (P < 0.01), as did plasma aldosterone concentration (1435 [1162,1722] to 753 [595, [110] fmol/mL; P < 0.01). Plasma vasoactive intestinal peptide was unchanged.4. Pregnant women respond to increased dietary sodium with an increase in plasma ANP in the absence of a significant increase in plasma volume. The acute regulation of plasma ANP in response to increases in dietary sodium in pregnant women does not appear to be mediated by changes in intravascular fluid volume.
RESPONSIVENESS AND SENSITIVITY TO CHOLINERGIC AGONISTS AND ANTAGONISTS IN BOVINE ISOLATED BRONCHIAL MUSCLE
Authors: Matera Maria G. , Cazzola Mario , Constantino Maria , De Santis Dante , Rossi Francesco 
Published: June 2007

SUMMARY1. Airways derived from different levels of the lung exhibit a difference in the reactivity and sensitivity to agonists. We have evaluated the effect of acetylcholine and cholinergic selective (pirenzepine, gallamine and 4‐dipherylacetoxymethyl piperidine [4‐DAMP]) and non‐selective (atropine) antagonists on bovine proximal and distal smooth muscle preparations.2. The distal preparations are more sensitive to acetylcholine than proximal bronchi. The relaxant effect of three selective antagonists on the distal and proximal tissues was the same when the results for each drug were compared.3. Atropine and 4‐DAMP were more potent than pirenzepine and gallamine in relaxing both proximal and distal bovine smooth muscle preparations.4. These data suggest that the muscarinic sites on the smooth muscle of bovine airways are of the M3 subtype.
THE TISSUE RENIN‐ANGIOTENSIN SYSTEM AND ITS FUNCTIONAL ROLE
Authors: Johnston C. I. , Burrell L. M. , Perich R. , Jandeieit K. , Jackson B. 
Published: June 2007

SUMMARY1. The components of the renin‐angiotensin system exist in many cardiovascular tissues (heart vessels, kidneys, adrenal glands).2. Angiotensin‐converting enzyme (ACE) is similar in somatic cells from all these sites.3. ACE contains two catalytic sites that have different conformation requirements. This suggests that each site may have different substrates and that specific inhibitors could be developed for each site.4. The cardiovascular functions of tissue ACE may include the regulation of regional blood flow, modulation of local sympathetic activity, stimulation of hyperplasia and hypertrophy and the mediation of inflammation.
EFFECT OF ENVIRONMENTAL AND HYPOTHALAMIC FACTORS ON THYROTROPIN SECRETION IN THE HYPOTHYROID RAT
Authors: Dou Yong‐Li , Tang Fai 
Published: June 2007

SUMMARY1. Fourteen days after hypothyroidism was induced either by propylthiouracil (PTU) treatment or by thyroidectomy, the serum thyrotropin (TSH) responses to morphine (5 or 20 mg/kg bw), ether stress (30 min) and cold exposure (60 min) were compared with those in normal rats.2. The decrease in serum TSH levels after morphine and ether stress found in the normal rats were abolished or much reduced respectively.3. The increase in serum TSH in response to cold exposure and the diurnal rhythm of serum TSH (lower level at night) were also absent in the hypothyroid rat.4. The stimulating effects of low dose of thyrotropin releasing hormone (TRH) and the inhibitory effects of somatostatin and apomorphine were completely abolished, while the stimulating effects of a high dose of TRH were much reduced in the hypothyroid rat.5. These results indicate that in the hypothyroid rat the effect of a lack of negative feedback action of thyroid hormone predominates, and that hypothalamic factors are probably unimportant in the regulation of TSH secretion.
11β‐HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN MESENTERIC ARTERIES OF SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Takeda Yoshiyu , Yoneda Takashi , Miyamori Isamu , Gathiram Premjith , Takeda Ryoyu 
Published: June 2007

SUMMARY1. 11β‐Hydroxysteroid dehydrogenase (11‐HSD) activity in mesenteric arteries of spontaneously hypertensive rats (SHR) and Wistar‐Kyoto (WKY) rats was determined and expressed as the percentage conversion of [3H]‐corticosterone to [3H]‐11‐dehydrocorticosterone.2. 11‐HSD activity was significantly decreased in mesenteric arteries of both 4 and 9 week old SHR (8.4 ± 0.8%, 5.0 ± 1.5%, respectively) compared with WKY rats (12.4 ± 0.6%, 15.8 ± 0.7%, respectively; P≤ 0.05).3. Total RNA from rat vascular smooth muscle cells (VSMC) and endothelial cells (EC) were prepared with selective precipitation in 3 mol/L LiC1/6 mol/L urea. The expression of 11‐HSD mRNA was confirmed in the rat VSMC but its mRNA expression was not detected in EC, using northern blot analysis.4. The results in this study indicate that 11‐HSD in the vascular wall may play a role in the pathogenesis of hypertension in SHR.
SPECIES DIFFERENCES IN BINDING OF SUBMANDIBULAR NUCLEAR PROTEINS TO RENIN PROMOTER DNA
Authors: Loudon John A. , Fukamizu Akiyoshi , Murakami Kazuo , Morris Brian J. 
Published: June 2007

SUMMARY1. Renin is highly expressed in submandibular gland (SMG) of mouse, which has two genes, Ren‐1d and Ren‐2d, but not at all in rat SMG. Differences in nuclear protein binding to renin promoter DNA were, therefore, explored.2. Rat ‐169 to +23 renin DNA formed complexes with both mouse and rat extract, whereas a corresponding fragment of mouse Ren‐Id DNA (‐121 to +4) bound with rat extract, but much less so with mouse extract. Rat extract bound a ‐704 to ‐450 fragment of the Ren‐1d promoter. For Ren‐2d ‐578 to ‐383 and ‐786 to ‐718 DNA bound with mouse extract and ‐383 to +11 and ‐664 to ‐ 578 DNA bound with rat extract.3. The results support a role for differences in presence or binding of species‐specific trans‐acting factors in the differential regulation of the renin gene in SMG of mouse and rat. Strong binding near the rat RNA polymerase II binding site could repress transcription in rat SMG, and binding peculiar to the Ret‐2d B2 element might contribute to high expression in mouse SMG.
RENAL SYMPATHETIC BAROREFLEX EFFECTS OF ANGIOTENSIN II INFUSIONS INTO THE ROSTRAL VENTROLATERAL MEDULLA OF THE RABBIT
Authors: Saigusa Takeshi , Head Geoffrey A. 
Published: June 2007

SUMMARY1. The effects of local infusion of angiotensin II (AII) into the rostral ventrolateral medulla (RVLM) pressor area on the renal sympathetic baroreflex were compared with the excitatory amino acid glutamate in urethane anaesthetized rabbits with chronically implanted renal nerve electrodes. Baroreflex blood pressure‐renal nerve activity curves were obtained by intravenous infusion of phenylephrine and nitroprusside before and after treatments.2. Infusion of 4 pmol/min of All into the RVLM increased blood pressure by 12 ± 2 mmHg and transiently increased resting sympathetic nerve activity. The renal sympathetic baroreflex curves were shifted to the right. The upper plateau of the sympathetic reflex increased by 29 ± 8% (n= 6, P < 0.025).3. Infusions of glutamate into the RVLM, at a dose which was equipressor to that of AII, also increased resting renal sympathetic nerve activity. In contrast to AII, this increase was maintained throughout the infusion. Glutamate shifted the reflex curve to the right and increased the upper plateau of the sympathetic reflex by 44 ± 5% without affecting the lower plateau.4. These results support the suggestion that AII can act at the level of the RVLM pressor area to facilitate baroreflex control of renal sympathetic activity in a similar fashion to that produced by fourth ventricular administration.5. Thus the RVLM is a likely candidate site for modulation of the renal sympathetic baroreflex. The similarity of the actions of AII to those of glutamate suggest that it may directly excite sympathetic vasomotor cells in this region.
PROLIFERATIVE EFFECT OF MEVALONATE METABOLITES OTHER THAN ISOPRENOIDS ON CULTURED VASCULAR SMOOTH MUSCLE CELLS
Authors: Sawamura Makoto , Li Nanfan , Nara Yasuo , Yamori Yukio 
Published: June 2007

SUMMARY1. Recent investigations revealed that isoprenoid compounds serve as key substances for cellular proliferation through post‐translational modification. Previously we reported that tissues of spontaneously hypertensive rats (SHR) had a lower activity of isoprenoid biosynthesis when compared with the normotensive control rat (WKY). However, cultured vascular smooth muscle cells (VSMC) of SHR showed an enhanced growth rate. These findings led us to investigate further the effect of isoprenoid compounds on VSMC proliferation.2. When the cells of WKY were stimulated with 5% fetal calf serum (FCS) in the presence of lovastatin, [3H]‐thymidine incorporation decreased in a dose‐dependent manner and was completely inhibited at 30 μmol/L. Exogenously added mevalonate showed a protective effect against lovastatin (81% protection at 0.1 μmol/L).3. Fluoromevalonate (Fmev), an inhibitor of mevalonate‐PP decarboxylase which converts mevalonate‐PP into isoprenoids, showed a dual inhibitory effect. DNA synthesis was partially inhibited at 0.01–1 μmol/L, however at 10 μmol/L there was no detectable inhibition. The inhibitory effect was again observed at concentrations over 10 μmol/L.4. In the presence of lovastatin and Fmev to block both HMG CoA reductase and mevalonate‐PP decarboxylase, exogenous mevalonate dose dependently stimulated [3H]‐thymidine incorporation induced by FCS.5. These data suggest the positive effect of the initial mevalonate derivatives other than isoprenoid compounds on the proliferation of VSMC.
EFFECT OF ATRIAL NATRIURETIC PEPTIDE ON CELLULAR ELEMENT CONCENTRATIONS IN RAT PROXIMAL TUBULES: EVIDENCE FOR INHIBITION OF THE SODIUM PUMP
Authors: Reddy Sri , Gyory Akos Z. , Dyne Marlen , Salipan‐Moore Noriah , Pollock Carol , Field Michael J. , Cockayne Dvid J. H. 
Published: June 2007

SUMMARY1. In order to further define the action of atrial natriuretic peptide (ANP) on proximal tubular (PT) transport, combined clearance and electron microprobe X‐ray (EMPX) experiments were performed on five male Wistar rats infused with ANP (0.16 nmol/kg per h) and nine control animals.2. Electron microprobe X‐ray analysis of PT cell electrolytes (mmol/ kg wet weight) revealed a similar [Na]i in both the control and ANP treated groups (16.4 ± 0.4 vs 16.5 ± 0.4; P= 0.894). [Cl]i was lower in the ANP treated animals (14.8 ± 0.3 vs 12.0 ± 0.3; P<0. 0001) as was [K]i (131.4 ± 1.4 vs 114 ± 1.7; P<0.0001). The PT cells in the ANP treated group had a significant reduction in dry weight (20.1 ± 0.3 g%vs 19.0 ± 0.3 g%; P<0.024), indicating significant cell swelling. Thus, despite a normal [Na]i, there was net accumulation of Nai following ANP treatment.3. These results are consistent with accumulation of Nai due to inhibition of the Na pump followed by cell swelling and subsequent regulatory volume decrease with exit of K and Cl. These results are the first to show the effect of ANP on PT intracellular electrolytes.
CENTRAL NEURONS AND NEUROTRANSMITTERS IN THE CONTROL OF BLOOD PRESSURE
Authors: Chalmers John , Arnolda Leonard , Llewellyn‐Smith Ida , Minson Jane , Pilowsky Paul , Suzuki Satoshi 
Published: June 2007

SUMMARY1. In this paper we review recent work from our laboratory on two major pathways important in the central control of blood pressure.2. We report experiments on the sympatho‐excitatory bulbospinal pathway from the rostral ventral medulla. Here we focus particularly on the role of excitatory amino acids.3. We review studies on the short inhibitory or depressor pathway ascending from the caudal to the rostral ventral medulla, which is thought to use γ‐aminobutyric acid (GABA) as its neurotransmitter. We report on experiments with the immediate early gene, c‐fos, demonstrating that its expression in the bulbospinal pressor neurons is increased by stimuli that activate these nerves, and that this expression can be blocked in vivo by treatment with an antisense oligonucleotide. We also show that basal and stimulated expression of the c‐fos gene is important in the central control of blood pressure.
EFFECTS OF ENALAPRIL AND DUP753 ON RENIN SYNTHESIS IN MICE WITH ONE HYDRONEPHROTIC KIDNEY
Authors: Zhang Yanling , Morgan Trefor 
Published: June 2007

SUMMARY1. Renin synthesis and secretion were investigated in mice with one hydronephrotic kidney.2. Enalapril and Dup753 stimulated renin synthesis to a similar extent in the hydronephrotic and normal kidney.3. Hydronephrosis did not prevent an increase in renin mRNA caused by enalapril and Dup753.4. The results therefore indicate that the macula densa does not appear to be crucial for renin synthesis in the kidney under the inhibition of angiotensin II.5. Thus angiotensin II plays an important role controlling renin gene expression in both the normal and hydronephrotic kidneys.
INTRACEREBROVENTRICULAR ANP(1–28) HAS NO OBVIOUS EFFECTS ON RENAL BLOOD FLOW AND FUNCTION IN CONSCIOUS SHEEP
Authors: Gunnarsson U. 
Published: June 2007

SUMMARY1. The study examines whether intracerebroventricular (ICV) infusion of atrial natriuretic peptide (human ANP, 1–28) influences renal electrolyte and water excretion, vasopressin release, renal and femoral blood flows in conscious ewes. The blood flow was measured by chronically implanted ultrasonic flow probes.2. ICV infusion of ANP(1–28) at 25 pmol/min for 60 min did not affect renal Na and K excretion or plasma vasopressin levels. In two out of six animals a mild water diuresis developed at about 50 min post‐infusion.3. The plasma osmolality, Na, K and protein concentrations did not change during the experiments.4. The renal and femoral arterial blood flows were not influenced by 30 min ICV infusions of ANP(1–28) at 25 and 85 pmol/min.5. It is concluded that human ANP(1–28) has no, or negligible, effects on renal function, femoral and renal blood flow when given ICV in amounts obviously elevating cerebrospinal fluid levels far above normal.
ROLE OF UTERINE FACTORS IN THE DEVELOPMENT OF HYPERTENSION IN SHR
Authors: Di Iulio Erkadius J. , Lucente F. , Bramich C. , Morgan T. , Nicolantonio R. Di 
Published: June 2007

SUMMARY1. To examine whether the uterine environment plays a role in the development of hypertension in the spontaneously hypertensive rats (SHR), we have compared fetal weight, placental weight, and amniotic fluid composition of SHR and Wistar‐Kyoto (WKY) rats after 20 days of gestation.2. Pregnant SHR and WKY were anaesthetized at 20 days of gestation and the uterus and embryonic sacs removed. Fetal and placental weights were recorded and amniotic fluid collected for measurement of volume, osmolality and electrolyte composition.3. No significant difference was found in litter size and placental weight between SHR and WKY. Total embryonic sac weight and fetal weight of SHR were significantly lower than WKY. Amniotic fluid volume, sodium concentration and osmolality of SHR were significantly higher than WKY, while amniotic fluid potassium concentration of SHR was significantly lower than WKY.4. Thus, the SHR foetus was significantly underweight compared to the WKY and was bathed in amniotic fluid with a significantly higher osmolality and sodium concentration. As the mature foetus is known to drink amniotic fluid, it is hypothesized that the elevated Na/K ratio in SHR amniotic fluid may instigate or accelerate the hypertensive process.
THE EFFECTS OF CENTRAL ADMINISTRATION OF ANGIOTENSIN II TYPE‐1 RECEPTOR ANTAGONIST, CV‐11974, IN NEPHRECTOMIZED SPONTANEOUSLY HYPERTENSIVE RATS
Authors: Kamitani Atsushi , Higashimori Koichi , Kohara Katsuhiko , Higaki Jitsuo , Mikami Hiroshi , Ogihara Toshio 
Published: June 2007

SUMMARY1. The role of the brain renin‐angiotensin system in the pathogenesis of genetic hypertension was evaluated using a specific non‐peptide angiotensin II type‐1 receptor antagonist, TCV‐116.2. CV‐11974 (active metabolite of TCV‐116) was acutely injected either intravenously (i.v.) or intracerebroventricularly (i.c.v.) in male spontaneously hypertensive rats (SHR; 12 week old). In separate groups of nephrectomized and sham‐operated SHR, graded doses of CV‐11974 were administered either i.v. or i.c.v. for 2 days using an osmotic minipump. In another group, the effects of nephrectomy on the depressor effect of chronic treatment with CV‐11974 were investigated. Haemodynamics at three points: before infusion, before nephrectomy and 48 h after nephrectomy, were monitored.3. Acute i.v. injection of CV‐11974 decreased blood pressure in the presence of the kidney. Prolonged i.c.v. administration of the drug for 2 days decreased blood pressure even at the lowest dosage, which had no hypotensive effects when given i.v. The hypotensive effect of centrally administered CV‐11974 was noted even 48 h after bilateral nephrectomy.4. These results suggest that the brain renin‐angiotensin system has a primary role in the maintenance of hypertension after eliminating the circulating renin‐angiotensin system in SHR.
EFFECT OF NEUTRAL ENDOPEPTIDASE ON PLASMA AND TISSUE CONCENTRATIONS OF VASO‐ACTIVE INTESTINAL PEPTIDE
Authors: Duggan K. A. , Jones D. M. , Davis R. E. , Macdonald G. J. 
Published: June 2007

SUMMARY1. This study sought to determine if neutral endopeptidase metabolizes vaso‐active intestinal peptide (VIP) and whether changes in the activity of this enzyme might explain the change in VIP metabolism which follows gastric sodium loading. The study also investigated whether prolonged inhibition of neutral endopeptidase was associated with inhibition of further secretion of VIP.2. Male Sprague‐Dawley rats were given the neutral endopeptidase inhibitor UK77,568 (10 mg/kg), or vehicle, tail vein injected, once or daily for 4 days. Two hours after injection the rats were anaesthetized, blood sampled to determine plasma concentrations of VIP and the hearts were harvested. Plasma and tissue concentrations of VIP were determined by radio‐immunoassay.3. Plasma VIP increased in response to UK77,568 at day 1 (P<0.0005) but did not differ from control at day 4. The concentration of VIP in the heart did not increase at day 1 but had increased significantly at day 4 (P<0.01).4. It was concluded that neutral endopeptidase may metabolize VIP. Further, the increased concentration of VIP in the heart and the return of its plasma concentration to control levels at day 4 may be consistent with suppression of continued VIP secretion.
EFFECTS OF ENDOTHELIN‐1 ON ARTERIAL PRESSURE: A COMPARISON OF INTRAVENOUS AND INTRA‐ARTERIAL ADMINISTRATION IN CONSCIOUS RABBITS
Authors: Roberts‐Thomson P. , McRitchie R. J. , Cain M. D. , Chalmers J. P. 
Published: June 2007

SUMMARY1. Intravenous endothelin‐1 releases endothelium‐derived relaxing factor (EDRF) and prostacyclin from the lungs, and substantial pulmonary clearance is claimed. Since these vaso‐active substances could alter the haemodynamic effects of endothelin‐1, the effects of boluses of endothelin‐1 injected intravenously and into the left ventricle (intra‐arterial) were compared, measuring arterial pressure and heart rate in conscious male New Zealand rabbits. The pulmonary clearance of endothelin‐1‐like immunoreactivity (Et‐1LI) and initial plasma half‐life were measured in anaesthetized rabbits during and after intravenous infusion of endothelin‐1.2. The effects of intravenous and intra‐arterial routes of administration were not significantly different. Arterial pressure decreased (intravenous: 21.6, intra‐arterial: 24.2 mmHg, P= 0.12, n= 10, t‐test, 9 d.f.), then increased (intravenous: 21.2, intra‐arterial: 16.4 mmHg, P= 0.33), while heart rate increased (intravenous: 66, intra‐arterial: 53 beats/min, P = 0.09), then decreased (intravenous: 50, intra‐arterial: 54 beats/min, P= 0.30).3. Arterial and venous plasma levels of Et‐1LI were not significantly different, venous levels increasing from 30 ± 3 pg/ mL (12 ± 1 pmol/ L) at 1 pmol/ kg per min to 770 ± 78 pg/ mL (308 ± 31 pmol/L) at 16 pmol/kg per min (n = 5). Mean initial plasma half‐life was 0.6 min (range: 0.25–1.1 min).4. It was concluded that there is no significant net pulmonary clearance of exogenously administered endothelin‐1 in the conscious rabbit, and that any vaso‐active factors released in the lungs by endothelin‐1 do not have a significant effect on systemic arterial pressure.