bluuebunny/crossref_metadata_2025 huggingface dataset:
TRANSCRIPTIONAL ACTIVATION OF CYTOCHROME P450 GENES BY DIFFERENT CLASSES OF CHEMICAL INDUCERS
Authors: Dogra Satish C. , Whitelaw Murray L. , May Brian K.
Published: June 2007

1. We review here the molecular mechanisms underlying the xenobiotic induction of genes encoding cytochrome P450 (CYP) enzymes in the liver and other tissues. We will focus on four major families of CYP genes.

2. Members of the CYP1 gene family are induced by polycyclic aromatic hydrocarbons and this process is mediated by the basic helix‐loop‐helix proteins: the Ah receptor and its heterodimeric partner Arnt. Considerable progress has been made in elucidating the molecular details of this induction process.

3. CYP4 genes are activated by peroxisomal proliferators, a group of structurally diverse chemicals that also induce peroxisome proliferation. The transcriptional response is dependent on the peroxisome proliferator‐activated receptor and its partner RXR, both members of the nuclear receptor super‐family; their role in the induction process has been well characterized at the molecular level.

4. In contrast, the mechanism of gene induction of CYP2 genes by phenobarbital and other structurally diverse inducers is not well understood and a specific phenobarbital‐responsive receptor has not been identified.

5. Induction of the CYP3 gene family by the glucocorticoid dexamethasone appears to involve the glucocorticoid receptor, but this receptor is not apparently required for induction by metapyrone and a complete molecular understanding of the induction processes is lacking at present.
ASSOCIATION OF PRE‐ISCHAEMIC DISTURBANCES IN ENERGY METABOLISM WITH POSTISCHAEMIC DYSFUNCTION OF THE RAT ISOLATED WORKING HEART
Authors: Pisarenko Oleg I. , Lakomkin Vladimir L. , Studneva Irina M. , Korchazhkina Olga V. , Kuzmin Alexander I. , Kapelko Valeri I.
Published: June 2007

1. Metabolic and functional effects of two protocols of preconditioning were compared in rat isolated hearts subjected to 20 min global ischaemia (37°C) and reperfusion (30 min Langendorff + 15 min working). Prior to the ischaemic period, hearts were perfused according to Langendorff (control group) or were preconditioned by three 5 min cycles or two 10 min cycles of ischaemia and reperfusion (PC‐I and PC‐II groups, respectively).

2. There was no difference in the contractile function between the two preconditioned groups at the onset of sustained ischaemia, although the PC‐II group showed enhanced release of adenosine (Ado), inosine, hypoxanthine and xanthine into the interstitium accompanied by losses of tissue adenine nucleotides (ΣAN = ATP + ADP + AMP), total creatine (ΣCr = phosphocreatine + creatine) and activation of glycolysis following the preconditioning period. During reperfusion, the PC‐I group showed enhanced functional recovery, higher contents of ΣAN and ΣCr, and the smallest lactate dehydrogenase release compared with these indices in the control and PC‐II groups. Postischaemic myocardial dysfunction was similar in the control and PC‐II groups.

3. Functional recovery of hearts in both preconditioned groups was positively correlated with myocardial contents of ATP, ΣAN and ΣCr at the end of reperfusion, but not with pre‐ischaemic Ado release into the interstitium. The results suggest that pre‐ischaemic disturbances of energy metabolism, rather than activation of Ado receptors or stunning, may contribute to efficacy of multiple preconditioning in the rat isolated heart.
ASSOCIATION STUDY OF THE 5’ FLANKING REGIONS OF ENDOTHELIAL‐NITRIC OXIDE SYNTHASE AND ENDOTHELIN‐1 GENES IN FAMILIAL PRIMARY OPEN‐ANGLE GLAUCOMA
Authors: Tunny Terry J. , Richardson Kimberley A. , Clark Charles V.
Published: June 2007

1. Endothelium‐derived substances are important regulators of the microcirculation. Endothelium‐derived nitric oxide (NO), which is catalysed by nitric oxide synthase (NOS), is a potent modulator of vascular tone in the human ophthalmic artery, which is normally in a state of constant vasodilation due to the actions of NO. Endothelin‐1 (ET‐1) produces vasoconstriction of the anterior optic nerve vasculature and may be associated with glaucomatous optic neuropathy. The aetiology of primary open‐angle glaucoma (POAG) remains largely unknown. Thus, alterations in the regulatory sequences of the genes coding for endothelium‐derived NOS (eNOS) and ET‐1 may have important effects in the development of POAG and were looked for in the present study.

2. In 56 patients with familial POAG and in 100 control subjects with no family history of hypertension or POAG, we examined the 5’ flanking sequences of the eNOS and ET‐1 genes, which contain many positive and negative regulatory regions affecting gene transcription, using polymerase chain reaction‐based single strand conformation polymorphism analysis, to search for alterations. No variant in the promoter region of the ET‐1 gene was observed in familial POAG or controls. Using three primer sets spanning 706 b.p. of the eNOS gene, we observed alterations in 11 of 56 (20%) familial POAG members and in seven of 100 (7%) controls. Sequence analysis demonstrated a C/T substitution at the 5’ sequence position nucleotide (nt) ‐690 from the transcription start site, which lies between the CAMP regulatory element (nt ‐726 to ‐732) and an activator protein‐1 binding domain (nt ‐655 to ‐661).

3. In summary, genotypic and allelic frequency analysis found no association between alterations in the promoter region of the ET‐1 gene and familial POAG. A variant in the promoter region of the eNOS gene was seen in a significant percentage of familial POAG patients. Future expression studies will determine whether this polymorphism results in altered eNOS gene expression.
UNIDIRECTIONAL TRANSFER OF D‐XYLOSE ACROSS THE RAT PLACENTA
Authors: Štaud F. , Fendrich Z. , Karlíček R. , Pávek P.
Published: June 2007

1. The transplacental transfer Of D‐Xylose was investigated in the present study.

2. Umbilical perfusion of the rat term placenta was used to study materno‐foetal (M‐F) and foetomaternal (F‐M) transfer of this compound.

3. D‐Xylose was found to cross the rat term placenta very quickly in the M‐F direction, with subsequent accumulation in the foetal compartment (the F‐M ratio being 2.23 at the end of the experiments). In contrast, no transfer in the F‐M direction was observed.

4. A possible facilitation of the transplacental transfer of D‐Xylose from the mother to foetus in rats is suggested.
IS INSULIN RESISTANCE LINKED TO HYPERTENSION?
Authors: Brands Michael W. , Hall John E. , Keen Henry L.
Published: June 2007

1. The volume of work reporting insulin resistance in multiple forms of chronic hypertension has generated tremendous interest in whether this abnormality is an important factor in causing hypertension. Insulin resistance, however, is an imprecise term used interchangeably to describe widely disparate types of impairment in insulin action throughout the body and the type of insulin resistance has major ramifications regarding its potential for inducing long‐term increases in blood pressure (BP).

2. Hepatic insulin resistance (impaired insulin‐mediated suppression of hepatic glucose output) is the primary cause of fasting hyperinsulinaemia and is a cardinal feature of obesity hypertension. Evidence from chronic insulin infusion studies in rats suggests hyperinsulinaemia can increase BP under some conditions; however, conflicting evidence in humans and dogs leaves in question whether hyperinsulinaemia is a factor in hypertension induced by obesity.

3. Peripheral insulin resistance (impaired insulin‐mediated glucose uptake, primarily of an acute glucose load in skeletal muscle) also present in obesity hypertension, but now reported in lean essential hypertension as well, is linked most notably to impaired insulin‐mediated skeletal muscle vasodilation. This derangement has also been proposed as a mechanism through which insulin resistance can cause hypertension.

4. The present review will discuss the lack of experimental or theoretical support for that hypothesis and will suggest that a direct link between insulin resistance and BP control may not be the best way to envision a role for insulin resistance in cardiovascular morbidity and mortality.
SEX STEROID CONTROL OF MOOD, MENTAL STATE AND MEMORY
Authors: Fink George , Sumner Barbara EH , McQueen Judith K. , Wilson Helen , Rosie Roberta
Published: June 2007

1. Sex steroid hormones exert profound effects on mood and mental state. Thus, in women, oestrogen is thought to protect against depression and delay the onset of schizophrenia and Alzheimer's disease.

2. Our studies in the female rat show that oestradiol, in its positive feedback mode for gonadotrophin release, increases the expression of genes for the 5‐hydroxytryptamine 5‐HT2A receptor and the serotonin transporter (SERT) in the dorsal raphe nucleus and the density of 5‐HT2A receptor and SERT sites in regions of the forebrain that, in the human, are concerned with cognition, mental state, emotion and memory.

3. In the male rat, castration decreases while oestrogen and testosterone, but not 5α‐dihydrotestosterone (5α‐DHT), increase the density of 5‐HT2A receptors in forebrain. The fact that 5α‐DHT has no effect suggests that the action of testosterone depends on its conversion to oestradiol by aromatase.

4. In intact rats, the density of 5‐HT2A receptors in cerebral cortex is significantly higher in prooestrous female than in male and dioestrous female rats, showing that the spontaneous, preovulatory surge of oestradiol that reaches a peak at 12.00 h of pro‐oestrus also increases the density of 5‐HTZA receptors in cortex.

5. Oestrogen and testosterone (by way of its conversion to oestrogen) also stimulate the expression of the arginine vasopressin gene in the bed nucleus of the stria terminalis of the rodent, a mechanism that plays a key role in olfactory memory.

6. These actions of sex steroid hormones are discussed in the context of genomic versus non‐genomic mechanisms, the recent discovery that there are two oestradiol receptors with different distributions in brain, the significance of our findings for our understanding of the control of mood, mental state and memory and the mechanism by which oestrogen stimulation of the 5‐HT2A receptor could delay the onset of Alzheimer's disease.
MECHANISMS UNDERLYING THE DECREASE IN CIRCULATING ANGIOTENSIN II CONCENTRATION AFTER SODIUM LOADING
Authors: Duggan KA , Ye VZC
Published: June 2007

1. Acute sodium loading causes a rapid decrease in the circulating concentration of angiotensin II (AngII), which is apparent from 5 min after sodium administration. This could result from an increase in AngII catabolism and/or a decrease in AngII synthesis/secretion. However, the major determinant of AngII synthesis is thought to be a change in plasma renin activity, which occurs over a longer time frame (15 min).

2. To investigate the mechanisms underlying the rapid decrease in plasma AngII engendered by sodium administration, we performed metabolic clearance studies in male New Zealand white rabbits before and after a hypertonic sodium load of 1.5 mmol/kg as 0.513 mol/L saline i.v. bolus.

3. The metabolic clearance rate of AngII increased significantly from 42.2 ± 9.0 mL/min per kg before sodium to 110.8±33.7 mL/min per kg after sodium administration (P<0.05). The calculated or theoretical secretion rate decreased from 1470.7±404.2 to 573.5 ± 139.5 fmol/min per kg (P<0.025) in response to sodium.

4. We conclude that an increase in AngII metabolism and a decrease in synthesis/secretion contribute to the reduction in circulating AngII, which occurs in the first 60–90 min after sodium loading.
ORIGIN AND FUNCTION OF EPOXYEICOSATRIENOIC ACIDS IN VASCULAR ENDOTHELIAL CELLS: MORE THAN JUST ENDOTHELIUM‐DERIVED HYPERPOLARIZING FACTOR?
Authors: Hoebel Bernhard G. , Steyrer Ernst , Graier Wolfgang F.
Published: June 2007

1. In addition to their contribution to endothelium‐derived hyperpolarization, our understanding of the physiological function of epoxyeicosatrienoic acids (EET) within the vascular wall and the actual enzymes involved in the formation of the EET in endothelial cells is very limited. In the present study, the expression of potential cytochrome P450 (CYP) mono/epoxygenases was assessed in endothelial cells isolated from porcine and bovine aortas as well as in the human umbilical vein‐derived cell lines EA.hy926andECV304.

2. Expression of CYP2B1, CYP2E1 and CYP3A could be found. The latter were inducible by dexamethasone/cloflbrate for 72 h, a procedure that also enhanced CYP epoxygenase activity in endothelial cells.

3. Enzyme induction yielded increases in capacitative Ca2+ entry and membrane hyperpolarization in response to autacoids, such as bradykinin and thapsigargin. Thiopentone sodium, an inhibitor of endothelial CYP mono/epoxygenase(s), diminished autacoid‐induced capacitative Ca2+ entry and membrane hyperpolarization, while the effect of EET remained unchanged.

4. Epoxyeicosatrienoic acids activated endothelial tyrosine kinase activity in a concentration‐dependent manner. Arachidonic acid, at 20‐fold higher concentrations, also increased tyrosine kinase activity. Because only the effect of arachidonic acid was inhibited by thiopentone sodium, an inhibitor of CYP mono/epoxygenases, these data suggest that arachidonic acid needs to be converted to the EET in order to stimulate tyrosine kinase.

5. All these data provide clear evidence that the CYP epoxygenase‐derived arachidonic acid metabolites (EET) not only serve as potential endothelium‐derived hyperpolarizing factors but also constitute highly active intracellular messengers with a physiological role including the control of Ca2+ signalling, membrane potential and tyrosine kinase activity.
PACEMAKING IN THE HEART: THE INTERPLAY OF IONIC CURRENTS
Authors: Saint David A.
Published: June 2007

1. There is still a degree of controversy about which currents drive pacemaking in the sinoatrial node or sinus venosus. Early attempts to identify a single ‘pacemaker current’ in these tissues, based on voltage‐clamp data, were largely unsuccessful, prompting the search for other mechanisms that may contribute to rhythmic activity.

2. Whole‐cell patch‐clamp recording from single cells isolated from the sinus venosus of the toad has shown that a voltage‐dependent sodium current may play a role in pacemaking. This current has a transient component that contributes to the action potential upstroke and an inactivation‐resistant component that contributes to the diastolic depolarization. The relative importance of this current in pacemaking is still controversial.

3. The development of computer models of pacemaking has contributed greatly to our understanding of how ionic currents can interact to produce rhythmic activity. Results are presented from one such model, ‘Oxsoft Heart', to illustrate the different contributions of If and INA and to highlight the concept that pace‐making is driven by the integrated activity of many processes, rather than by any one current in particular.

4. Present models of pacemaking fail to accurately reproduce biological observations for certain situations. It is becoming clear that many processes contribute to pacemaking and have yet to be fully incorporated into models. Recent results regarding the role of intracellular calcium buffering and release and their implications, are discussed in this context.

5. The control of pacemaking by neurotransmitters is discussed. The limitations of single cell models in reproducing many of the complex responses to nerve stimulation of multicellular tissue, such as postinhibitory rebound, are discussed and possible improvements to models are suggested.
KATP CHANNEL BLOCKING ACTIONS OF QUATERNARY IONS PLAY NO ROLE IN THEIR ANTIPROLIFERATIVE ACTION ON MOUSE LEUKAEMIA AND RAT VASCULAR SMOOTH MUSCLE CELLS IN VITRO
Authors: Piekarska Anna E. , Webster Lorraine , Saltis John , McPherson Grant A.
Published: June 2007

1. The aim of the present study was to investigate the possibility that, in the two cell lines examined, alterations in cell growth caused by lipophilic quaternary ions may involve KATP channels. We examined the effect of tetraphenylphosphonium (TPP), tetraphenylboron (TPB), rhodamine 123, dequalinium chloride (DECA) and the non‐quaternary ion cisplatin on the proliferation of L1210 mouse leukaemia cells and rat smooth muscle cells in vitro. The KATP channel opener levcromakalim (LKM) and the Katp channel antagonist glibenclamide were also tested.

2. From growth‐inhibition studies, the rank order of potency (based on pIC50 values) using L1210 leukaemia cells was: DECA (6.61) > cisplatin (6.09) = rhodamine 123 (6.01) > TPP (5.61) > TPB (4.25). Levcromakalim and glibenclamide were found to be inactive at the maximum concentrations used (100 μmol/L). A different rank order of potency was obtained in rat aortic smooth muscle cells: cisplatin (6.33) > DECA (5.67) > TPP (4.96) > rhodamine 123 (4.1). Tetraphenylboron (30μmol/L), LKM (100 μmol/L) and glibenclamide (100 μmol/L) were found to be inactive.

3. When the negatively charged TPB (30 μmol/L) was combined with some of the active agents, the potency of the active agents was increased. Thus, in L1210 cells, rhodamine 123, DECA and TPP were all more potent at inhibiting cell growth in the presence of TPB. Tetraphenylboron had no effect on cisplatin in this cell line. In rat smooth muscle cells, TPB (30 μ mol/L) potentiated the effect of rhodamine 123 but had no effect on the actions of cisplatin, DECA or TPP.

4. In functional studies, rhodamine 123 was a weak antagonist of the vasorelaxant responses to the KATP channel opener LKM in the porcine right circumflex artery in vitro. The pKB value obtained for rhodamine 123 at 100 μmol/L was 4.95. Dequalinium chloride was inactive.

5. We found no correlation between the actions of the compounds tested to antagonize KATP channels and their ability to inhibit cell proliferation. In addition, compounds known to regulate KATP channel activity failed to influence proliferative rates. These results suggest that KATP channels are not involved in the antiproliferative action of TPP and other quaternary ions in the two cell lines studied.
EFFECTS OF ZAPRINAST ON RENAL NERVE STIMULATION‐INDUCED ANTI‐NATRIURESIS IN ANAESTHETIZED DOGS
Authors: Sekizawa Toshihiro , Shima Yuichiro , Yoshida Kozo , Tanahashi Masayuki , Yoshida Makoto , Suzuki‐Kusaba Mizue , Hisa Hiroaki , Satoh Susumu
Published: June 2007

1. We examined whether zaprinast, a putative cGMP‐specific phosphodiesterase inhibitor, affects neural control of renal function in pentobarbital‐anaesthetized dogs.

2. Renal nerve stimulation (1Hz, 1ms duration) reduced urine flow rate, urinary Na+ excretion (UNaV) and fractional excretion of Na+ (FENa) with little change in either renal blood flow (RBF) or glomerular filtration rate (GFR).

3. Intrarenal arterial infusion of zaprinast (10 and 100 μg/kg per min) increased basal urine flow rate, UNaV and FENa but not RBF or GFR. Zaprinast infusion (100 μg/kg per min) also increased renal venous plasma cGMP concentration and urinary cGMP excretion.

4. Renal nerve stimulation‐induced reductions in UNaV and FENa were attenuated during zaprinast infusion, whereas the reduction in urine flow rate was resistant to zaprinast.

5. Renal nerve stimulation increased the renal venous plasma noradrenaline concentration and renal noradrenaline efflux, which remained unaffected during infusion of zaprinast (100 μg/kg per min).

6. The results of the present study suggest that zaprinast induces natriuresis and counteracts adrenergically induced anti‐natriuresis by acting on renal tubular sites in the dog kidney in vivo.
MODULATORY EFFECTS OF TYPE‐C NATRIURETIC PEPTIDE ON SYMPATHETIC COTRANSMISSION IN THE RAT ISOLATED TAIL ARTERY
Authors: Mutafova‐Yambolieva Violeta N. , Westfall David P.
Published: June 2007

1. Rat type‐C natriuretic peptide (CNP) has been studied for its effects on the neurogenically induced overflow of adenosine 5′‐triphosphate (ATP), adenosine 5′‐diphosphate (ADP), adenosine 5‐monophosphate (AMP), adenosine (ADO) and noradrenaline (NA) in endothelium‐free segments of rat isolated tail artery. The overflow of each was evoked by electrical field stimulation (EFS) of 0.5 ms pulses at 8 Hz for 3 min and the amount of ATP, ADP, AMP and ADO was quantified by high‐performance liquid chromatography (HPLC)‐fluorescent detection, while the amount of NA was quantified by HPLC‐electrochemical detection.

2. Type‐C natriuretic peptide (100 nmol/L) was found to cause a significant reduction of the overflow of all adenine purines and NA. However, at lower concentrations (1 and 10 nmol/L), CNP caused a significant reduction of the overflow of NA but did not change ATP overflow.

3. The overflow of ADP, AMP and ADO was significantly reduced by either concentration of CNP, so that the ratio ATP:ADP was diminished from 1:2 in controls to 1:1 after 1 nmol/L CNP and to 1:1.2 after 10 nmol/L CNP.

4. The production of inorganic phosphate (Pi) in response to the exogenous application of ATP was significantly reduced by 1,10 or 100 nmol/L CNP.

5. Type‐C natriuretic peptide exerts neuromodulatory effects on the neurogenically induced release of the cotransmitters ATP and NA in rat tail artery, consisting of an inhibition of the release of both ATP and NA. This effect is accompanied by inhibition of the breakdown of ATP by ecto‐ATPases. Either effect results in apparent CNP‐induced differential modulation of the overflow of the cotransmitters ATP and NA.
ANGIOTENSIN‐CONVERTING ENZYME INHIBITION IN PIGLETS INDUCES PERSISTENT RENAL ABNORMALITIES
Authors: Guron Gregor , Sundelin Birgitta , Wickman Anna , Friberg Peter
Published: June 2007

1. We have previously shown that neonatal angiotensin‐converting enzyme (ACE) inhibition or angiotensin II type I (AT1) receptor antagonism during the first three postnatal weeks in the rat produces persistent abnormalities in renal function and histology, indicating an essential role for the reninangiotensin system (RAS) in normal renal development.

2. The aim of the present study was to investigate whether the pig kidney, which shows a high resemblance to the human kidney, is dependent on an intact RAS neonatally for normal renal development, analogous with findings in rats.

3. Piglets received daily i.p. injections of either enalapril (10 mg/kg) or vehicle from 2 to 24 days after birth. Urine concentrating capacity, renal functional parameters and renal histology were assessed in 8‐week‐old pigs.

4. Urine osmolality after 20 h water deprivation was 673 ± 55 and 928 ± 50 mOsm/kg (P < 0.05) in enalapril‐ and vehicle‐treated pigs, respectively. There were no significant differences between groups in plasma creatinine or urea concentrations.

5. Semiquantitative analysis of renal histology showed significant interstitial fibrosis and inflammation, tubular atrophy and thickened walls of interlobular arteries in enalapril‐treated pigs.

6. The present study demonstrates that an intact RAS is required for normal renal development in the pig, similar to previous observations made in rodents.
17β‐OESTRADIOL ENHANCES NITRIC OXIDE SYNTHASE ACTIVITY IN ENDOTHELIUM‐DENUDED RAT AORTA
Authors: Binko J. , Murphy TV , Majewski H.
Published: June 2007

1. It has been suggested that oestrogen‐produced vasodilatation is due to induction of endothelial nitric oxide synthase (NOS), but there are many reports of direct effects on vascular smooth muscle. In the present study, these processes were investigated in rat aorta isolated from ovariectomized rats.

2. Short‐term treatment (10min) with 17β‐oestradiol (10 μmol/L) produced a small attenuation of the phenylephrine (PE)‐induced constriction, which was unaffected by the nitric oxide synthase inhibitor l‐N 5(‐1‐iminoethyl)ornithine (NIO; 100μmol/L). Long‐term treatment (6h) with 17β‐oestradiol (10 μmol/L) did not affect acetylcholine‐mediated vasorelaxation in endothelium‐intact aortic rings, but did attenuate PE‐induced constriction. This attenuation was also observed in endotheliumdenuded preparations after 17β‐oestradiol (10 μmol/L for 6h) and was far greater than the acute effect of 17β‐oestradiol (10 μmol/L).

3. The attenuation produced by 17β‐oestradiol (10 μmol/L for 6 h) was significantly inhibited by concomitant treatment with cycloheximide (1 μmol/L), suggesting that protein synthesis was involved. NIO (100 μmol/L) also attenuated the effect, which suggests that the anti‐constrictor effect of 17β‐oestradiol occurs through the increased production of nitric oxide (NO). 17β‐Oestradiol increased NO production, as assessed by the conversion of [3H]‐arginine to [3H]‐citrulline in rat aorta. These effects were prevented by cycloheximide and NIO. The anti‐constrictor effect of oestrogen was blocked by the oestrogen receptor antagonist ICI 182780 (100nmol/L).

4. Western blotting using an antibody specific for inducible nitric oxide synthase (NOS) revealed that 17β‐oestradiol (10 μmol/L for 24 h) treatment induced the formation of inducible NOS protein in the aorta, an effect blocked by cycloheximide. The results indicate that 17β‐oestradiol can attenuate the vasoconstrictor effect of PE by a specific receptor‐mediated process that involves induction of inducible NOS.
PATTERNS OF CIRCADIAN BODY TEMPERATURE RHYTHMS IN AGED RATS
Authors: Satinoff Evelyn
Published: June 2007

1. Old rats of the same chronological age are not homogeneous with respect to their circadian temperature rhythm (CTR). Some old rats maintain a robust CTR, comparable with that of young rats, while others have a weakened and unstable CTR. Often, in the latter group, the CTR becomes flat and disappears. In almost all old rats there is a clear decrease in the amplitude of the CTR.

2. The present paper describes several methods that are useful for distinguishing between old rats in different categories. Three patterns can be distinguished: (i) good (there is a clear difference between the daily body temperature (Tb) means in the light and dark, relatively high density (power) at a period of 24 h, low hour‐to‐hour fluctuation in Tb within a given day (low intradaily variability; IV) and high day‐to‐day stability in Tb (high interdaily stability; IS)); (ii) unstable (there is a variable difference between daily Tb means in the light and dark, very low density at the 24 h period, moderate IV and low IS); and (iii) flat (there is little or no difference or variation in daily Tb means in the light and dark, low or insignificant density at 24 h, highest IV and lowest IS).

3. The importance of these distinctions in old rats is two‐fold. First, differences at a behavioural level may reflect fundamental differences in the brain. Second, the degree of deficits in one system, for example in the CTR, may be correlated with deficits in other systems, such as sleep‐waking. The methods described in the present paper are useful for obtaining qualitative information on the progressive deterioration of the CTR as animals age.
Experimental Biology 1997 Symposium on Neurobiology of Thermoregulation: Role of Stress: THERMOREGULATORY CHANGES BY HYPOXIA: LESSONS FROM THE PARAMECIUM
Authors: Malvin Gary M.
Published: June 2007

1. In organisms ranging from paramecia to mammals, hypoxia elicits a regulated decrease in body temperature (Tb). A decrease in Tb is an important adaptation to hypoxia primarily because it lowers metabolic rate when oxygen supply is limited, thus facilitating survival.

2. Although this beneficial response is extremely widespread among taxa, little is known of the cellular mechanisms that mediate hypoxia‐induced decreases in Tb. This is due, in large part, to the extreme complexity of vertebrate thermoregulatory systems.

3. The thermoregulatory system of the unicellular paramecium is much simpler than that of vertebrates, yet it responds similarly to hypoxia. Research has explored the functional importance of hypoxia‐induced decreases in Th. In addition, a number of possible mediators and signalling pathways in hypoxia‐induced reductions in Tb have been assessed.

4. In Paramecium caudatum, hypoxia appears to exert its thermoregulatory effects by inhibiting oxidative phosphorylation. Decreases in intracellular [ATP] and pH may be important intermediate signals. In addition, an endogenous opioid system appears to help mediate hypoxia‐induced changes in thermoregulatory behaviour.
ANGIOTENSIN II‐ AND PHORBOL ESTER‐INDUCED STEROIDOGENESIS BY OVINE ADRENOCORTICAL CELLS: EFFECT OF SEX AND THE GONADAL STATUS OF THE DONOR ANIMAL
Authors: Canny BJ , O'Farrell KA , Clarke IJ , Tilbrook A J.
Published: June 2007

1. Angiotensin II (Angll) is well recognized as a regulator of adrenal Cortisol production in the sheep in vivo, but studies to date have failed to reveal this action on cultured ovine adrenocortical cells. Similarly, phorbol myristate acetate (PMA), an activator of protein kinase C, also has little effect on Cortisol production from ovine adrenocortical cells in vitro. Previous studies have, however, only looked at the responses to single concentrations of Angll or PMA, but have led to the suggestion that important differences exist between adrenocortical cells of the sheep and other species.

2. We have extended previous studies by examining Cortisol production by ovine adrenocortical cells over 3h in response to a broad range of concentrations of either Angll (10−10 to 10−6mol/L) or PMA (10−10 to 10−5mol/L). In addition, we have investigated the possible role of gonadal factors in regulating these responses by comparing cultures derived from intact and gonadectomized male and female sheep.

3. Angiotensin II caused concentration‐dependent increases (P<0.05) in Cortisol production in all cultures, with Cortisol production in response to Angll being greater (P < 0.05) in cultures from intact male sheep than in the cultures from orchid‐ectomized males or intact females. Cortisol production in response to Angll was modest in all groups (two‐ to 2.6‐fold increases).

4. Phorbol myristate acetate elicited a concentration‐dependent inhibition (P<0.01) of basal Cortisol production in adrenocortical cultures from all groups. Phorbol myristate acetate produced a greater inhibition (P<0.05) of Cortisol production in cultures from intact male sheep than either the orchidectomized males or intact females.

5. These findings demonstrate that ovine adrenocortical cells are responsive in a concentration‐dependent fashion to Angll and PMA. In addition, sex and gonadal factors may play an important role in regulating the responsiveness of adrenocortical cells to these factors.
CLORICROMENE REDUCES INFARCT SIZE AND ALTERS POSTISCHAEMIC BLOOD FLOW DEFECTS IN DOG MYOCARDIUM
Authors: Groban Leanne , Zvara David A. , Deal Dwight D. , Vernon Jason C. , Flye Christopher W. , Ma Xin‐Liang , Vinten‐Johansen Jakob
Published: June 2007

1. The aim of the present investigation was to evaluate the effect of cloricromene on myocardial infarct size, regional myocardial blood flow and neutrophil accumulation in a canine model of ischaemia‐reperfusion.

2. Dogs were instrumented to measure blood pressure, left anterior descending (LAD) coronary flow (flow probe) and regional myocardial blood flow (coloured microspheres). Two groups were studied: (i) CLO (n= 8) received an infusion of cloricromene (15 μg/kg per min); and (ii) VEH (n= 8) received saline. Infusions began at the onset of ischaemia (60 min) and continued through reperfusion (180 min).

3. Haemodynamic responses were not different between groups. Cloricromene reduced the area of necrosis expressed as a percentage of the area at risk from 35 ± 3% in the VEH group to 23 ± 4% in the CLO group (P<0.05). Regional myocardial blood flow in the ischaemic region was different between groups; VEH dogs showed an early reperfusion hyperaemia followed by a progressive reduction in flow, while CLO dogs exhibited a gradual increase in reflow in the absence of an early hyperaemie response (P<0.05). Left anterior descending flow was enhanced during the reperfusion period in the CLO group compared with VEH (P<0.05). Cloricromene reduced polymorphonuclear neutrophil (PMN) infiltration (myeloperoxidase activity) in all myocardial regions when compared with VEH (non‐ischaemic zone, 0.34 ± 0.54 vs 0.05 ± 0.01 IU/l00 mg; ischaemic zone, 2.03 ± 0.80 vs 0.24 ± 0.08 IU/100 mg; and necrotic zone, 0.56 ± 0.04 vs 3.59 ± 1.09 IU/100 mg for VEH vs CLO groups, respectively; P<0.01). In a separate in vitro preparation, cloricromene reduced adherence of platelet‐activating factor (PAF)‐stimulated PMN to canine coronary endothelium. Stimulation of PMN by 100 nmol/L PAF resulted in adherence of 176 ± 36 compared with 48 ± 12 cells/mm2 in PAF‐stimulated PMN treated with 100 p. mol cloricromene (P<0.001).

4. These data indicate that cloricromene reduces myocardial infarct size in a canine model of ischaemia‐reperfusion injury.

Postischaemic blood flow patterns are significantly different in cloricromene‐treated dogs. Cloricromene‐mediated reductions in infarct size, neutrophil accumulation and adherence may play a role in this effect.
EFFECTS OF FR139317 ON RENAL RESPONSES TO ACUTE NITRIC OXIDE BLOCKADE IN ANAESTHETIZED RATS
Authors: Matsumura Yasuo , Kuro Toshihiko , Hashimoto Norio , Taira Shima
Published: June 2007

1. Effects of FR139317, an endothelin ETA receptor antagonist, on renal haemodynamic and excretory responses to acute nitric oxide (NO) blockade were examined using anaesthetized rats.

2. Intrarenal arterial infusion of NG‐nitro‐l‐arginine (NOARG), the NO synthase inhibitor, at a rate of 40 μg/kg per min, produced a significant decrease in renal blood flow, with no change in systemic blood pressure. There were significant decreases in urine flow and urinary excretion of sodium during infusion of NOARG. In animals pretreated with FR139317, similar renal responses to the NOARG infusion were observed.

3. These results suggest that an action of endothelin‐1 via ETA receptors does not greatly contribute to the renal haemodynamic and excretory responses to acute blockade of renal NO production.
VENTRAL MEDULLARY CHEMORECEPTOR INPUTS TO NEURONS WITHIN THE NUCLEUS AMBIGUUS
Authors: Lewis DI
Published: June 2007

1. The neural mechanisms by which neurons within the nucleus ambiguus respond to chemoreceptor stimuli applied to the ventral medullary surface (VMS) were investigated by determining the effect of low pH on the membrane potential and synaptic activity of these neurons in vitro.

2. Small reductions in pH evoked an indirect membrane depolarization and/or an increase in excitatory synaptic activity in the majority of neurons. A direct membrane hyperpolarization was observed in the remaining neurons.

3. Acetylcholine evoked a direct nicotinic receptor‐mediated membrane depolarization in these neurons. In addition, 37% of neurons received muscarinic synaptic input that originated from neurons located near the VMS.

4. Low‐pH artificial cerebrospinal fluid (aCSF) potentiated the cholinergic component of the excitatory post‐synaptic potential (EPSP) evoked from near the VMS. Both this EPSP and the spontaneous EPSP evoked by low‐pH aCSF could be blocked by atropine.

5. It is concluded that at least two different mechanisms exist to transmit chemoreceptive information from the VMS to neurons within the nucleus ambiguus. In the majority of neurons, an indirect excitatory response is observed that is due, in part, to activation of a polysynaptic cholinergic pathway originating near the VMS. In the remaining neurons, low pH evokes a hyperpolarization that is due to a direct action of the dendrites of the neurons themselves that project near to the VMS.
REGIONAL BRAIN ACTIVATION IN HUMANS DURING RESPIRATORY AND BLOOD PRESSURE CHALLENGES
Authors: Harper Ronald M. , Gozal David , Bandler Richard , Spriggs David , Lee Jason , Alger Jeffry
Published: June 2007

1. The aim of the present study was to determine the brain sites mediating aspects of respiratory and cardiovascular control in adult humans using non‐invasive functional magnetic resonance (/MRI) procedures, thereby avoiding the spatial and temporal sampling limitations associated with classic neural assessment techniques.

2. We examined activity changes across the entire brain following application of respiratory loads and upon induction of blood pressure and heart rate alterations. Magnetic resonance signals were visualized with a 1.5Tesla scanner in healthy volunteers (22‐52 years of age) using procedures that optimally assess changes in brain tissue microcirculation. Images were collected during a Valsalva manoeuvre, inspiratory loading, hypercapnia, cold pressor challenges to the hand and forehead and during intervening baseline states.

3. Image values from experimental conditions were compared with corresponding baseline values on a pixel‐by‐pixel basis to identify brain regions in which the experimental conditions produced physiological activation.

4. Ventilatory and pressor challenges elicited significant changes in regional image signal intensity in areas within the orbital cortex, amygdala, hypothalamus and hippocampus. Cerebellar, medullary and pontine areas were also recruited. However, while particular brain regions were only activated during specific stimuli, other regional signal changes occurred with multiple experimental manipulations.

5. The findings indicate that respiratory and cardiac challenges elicit discrete activity changes over multiple brain sites. Activated regions include structures not often related to respiratory or cardiovascular regulation, such as the cerebellum; a prominent role for limbic forebrain structures in mediating the response is also suggested. The f MRI visualization procedures may greatly assist in the determination of neural structures that mediate respiratory and cardiovascular control in humans.
INTERFERON‐INDUCER POLYRIBOINOSINIC‐ POLYRIBOCYTIDYLIC ACID: A POTENT ANTI‐GASTRIC ULCER AGENT AND INHIBITOR OF THE GASTRIC PROTON PUMP IN RATS
Authors: Nath C. , Rastogi L. , Dikshit M. , Patnaik GK , Saxena RC , Gupta MB
Published: June 2007

1. Polyriboinosinic‐polyribocytidylic acid (Poly I:Poly C), an interferon inducer was studied for its effect on gastric ulceration in rats. Polyriboinosinic‐polyribocytidylic acid (1,2 and 4 mg/kg, i.m.) showed a dose‐dependent inhibition of gastric ulcers induced by aspirin, cold restraint stress and pylorus ligation (Shay's model). Protective dose (PD50)±SEM values of Poly I:Poly C on these models of ulcers were 1.9±0.2, 2.3±0.4 and 2.8±0.4 (mg/kg, i.m.) respectively.

2. Polyriboinosinic‐polyribocytidylic acid (10‐60 μg) produced dose‐dependent inhibition of gastric proton pump (H+/K+‐ATPase) activity in the gastric parietal microsomal fraction. The concentration of Poly I:Poly C causing a 50% inhibition (IC50)±SEM was found to be 17.6±1.2 μg.

3. Polyriboinosinic‐polyribocytidylic acid caused a significant decrease in free and total acid and pepsin and an increase in mucin content in Shay (pylorus‐ligated) rat.

4. Polyriboinosinic‐polyribocytidylic acid did not exert a significant influence on isolated tissue preparations for anticholinergic (acetylcholine‐induced contraction of guinea‐pig ileum) and H2‐anti‐histaminic (histamine‐induced contraction of rat uterus and guinea‐pig auricle) activities.

5. Thus, the present study indicates that Poly I:Poly C may possess anti‐gastric ulcer activity as a result of inhibition of the gastric proton pump.
ASCITES FLUID OF NEPHROTIC RATS: SODIUM DODECYL SULPHATE‐POLYACRYLAMIDE GEL ELECTROPHORESIS PROTEIN PATTERN AND THE RENIN‐ANGIOTENSIN SYSTEM
Authors: Cruz C. , Correa‐Rotter R. , Mézquita C. , Medina‐Campos ON , Pedraza‐Chaverri J.
Published: June 2007

1. The concentration of renin and angiotensinogen (Ao) and the activity of angiotensin I‐con verting enzyme (ACE) was measured in the ascites fluid of nephrotic rats obtained 8 days after puromycin aminonucleoside (PAN) injection.

2. Ascites fluid, serum and urine proteins of these rats were analysed by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS‐PAGE).

3. Renin, Ao and ACE were found in the ascites fluid and the percentage of the ratio ascites fluid/(plasma or serum) ranged from 5.9 to 9.9%. The electrophoretic analysis revealed that the ascites fluid contained low (Mr < 66 kDa) and high (Mr < 66 kDa) molecular weight proteins. Albumin and six proteins higher than 66 kDa were present both in the ascites fluid and in serum from nephrotic rats.

4. Data from the study suggest that some proteins in the ascites fluid, including renin, Ao and ACE, come from the plasma. It is possible that the loss of renin, Ao and ACE to the ascites fluid may be playing a role in the metabolic alterations of these three proteins in PAN‐nephrotic rats.
ANTI‐PROLIFERATIVE EFFECTS OF UNMODIFIED ANTISENSE OLIGODEOXYNUCLEOTIDES TARGETED AGAINST c‐raf mRNA: USE OF POLY (LYSINE/SERINE) COPOLYMERS OR CATIONIC LIPOPOLYAMINES
Authors: Aoki Y. , Kawa S. , Karasawa Y. , Horiuchi A. , Kiyosawa K.
Published: June 2007

1. It is now known that nuclease‐resistant phosphorothioate antisense oligodeoxynucleotides (ODN) have some actions that are unrelated to antisense mechanisms. In the present study we assessed the anti‐proliferative effects of phosphorothioate (PS) and phosphodiester (PO; unmodified) antisense ODN targeted against c‐raf mRNA on pancreatic cancer cells in vitro, using poly (lysine/serine) copolymers conjugated with polyethylene glycol (PLSP) or cationic lipopolyamines (Transfectam) as carriers.

2. The anti‐proliferative effect of the PO antisense ODN was significantly (P < 0.05) greater than that of the PS ODN, either complexed with PLSP (2 μmol/L ODN) or the Transfectam (0.5 μmol/L ODN). However, the effect of the PS or PO antisense ODN was not dependent on the antisense sequence. The c‐raf mRNA levels, assessed by reverse transcription‐polymerase chain reaction, were obviously reduced by both PO and PS anti‐sense ODN compared with mismatched ODN when complexed with the Transfectam (1 μmol/L ODN).

3. Although the anti‐proliferative effects were mainly unrelated to antisense mechanisms, unmodified antisense ODN complexed with some carriers could be used as anti‐tumour agents considering that synthetic carriers can be modified to improve functions, such as delivery.
AUTACOID INTERACTIONS IN THE REGULATION OF BLOOD FLOW IN THE HUMAN PLACENTA
Authors: Gude NM , King RG , Brennecke SP
Published: June 2007

1. Interactions between autacoids may play important roles in the regulation of blood flow in the foetal placenta. In order to investigate this aspect of placental haemodynamics, human normal‐term placentae were perfused in vitro and the responses of the foetal vessels to various combinations of vasoactive agents were determined.

2. Vasoconstriction responses to 5‐hydroxytryptamine (5‐HT) were potentiated in the presence of endothelin‐1 (ET‐1), the thromboxane A2‐mimetic U46619 and a nitric oxide synthase inhibitor, N‐nitro‐l‐arginine (NOLA), but not in the presence of angiotensin II.

3. N‐Nitro‐l‐arginine caused vasoconstriction of the perfused placenta and indomethacin attenuated this effect and blocked the potentiation of the 5‐HT response by NOLA.

4. Indomethacin did not affect ET‐1‐induced pressure increases and infusion of U46619 had no effect on release of ET‐Iike immunoreactivity into the foetal placental circulation.

5. The present study provides evidence of interactions between several autacoids in human perfused placentae in vitro. These interactions may play important roles in foetal placental haemodynamics in normal or pathological situations.
UREA: DIVERSE FUNCTIONS OF A ‘WASTE” PRODUCT
Authors: Withers Philip C.
Published: June 2007

1. The urea cycle is essentially the simultaneous operation of two linear pathways, both primitive and widespread among animals; one is for arginine synthesis and the other is for arginine degradation to ornithine and urea.

2. All animals may have the genetic capacity to express a urea cycle and many diverse groups of animals, from flatworms to mammals, have a functional urea cycle.

3. Evolutionary changes in vertebrates of carbamyl‐phosphate synthetase (CPS) are directed from glutamine‐dependent (CPSIII) towards NH3‐dependent (CPSI) ureagenesis. Invertebrates, cartilagenous fish and the coelacanth have CPSIII (i.e. glutamine‐dependent), whereas lungfish, amphibians and amniote vertebrates have CPSI; the teleost Heteropneustes has CPSI‐like activity. That the coelacanth has CPSIII and Heteropneustes has ‘CPSI’ suggests that the form of CPS may by physiologically related (CPSIII in a balancing solute role and CPSI in a terrestrial, air‐breathing excretion role) rather than being phylogenetically constrained.

4. Urea is a major balancing osmolyte in marine cartilagenous fish, the coelacanth and a few amphibians and some aestivating terrestrial amphibians. It is a storage osmolyte in cocoon‐forming aestivating lungfish and amphibians.

5. Urea contributes towards positive buoyancy in marine cartilagenous fish.

6. Urea functions for non‐toxic N transport in ruminant and pseudoruminant mammals

7. Urea is a major solute in the mammalian (but not avian) kidney, contributing to a renal medullary osmotic gradient; it is substantially reabsorbed by mammalian nephrons.

8. Urea is used as a preferred nitrogenous waste compared with ammonia at high ambient pNH3 or pH, with water restriction, or air breathing.

9. Urea synthesis maintains acid‐base balance by the 1:1 stoichiometry of removal of HCO3− and NH4+.
ARE EXTANT LUNGFISH NEOTENIC?2
Authors: Joss Jean MP
Published: June 2007

1. The thyroid axis in developing lungfish is being explored to ascertain whether it shows similar deficiencies to those characteristic of neoteny in urodele amphibians.

2. At hatching, the pituitary of Neoceratodus forsteri comprises a lumen surrounded by a single layer of epithelial cells lying immediately below the hypothalamus, but unconnected to it. Over the first year of development, the number of pituitary cells increases and several cell types, including thyrotropes, can be recognized immunocytochemically, but the pituitary remains unconnected to the hypothalamus.

3. By treating the lungfish with thyroid inhibitor, no increase in thyroid uptake of iodine, indicative of induced pituitary thyroid‐stimulating hormone (TSH) activity, could be demonstrated; neither was there any response to exogenous human TSH. In the liver, thyroid hormone receptors were found to be primarily of the a type.

4. Taken together, these findings suggest that up to 1 year of age, lungfish development is equivalent to amphibian premeta‐morphosis, which is consistent with neoteny but cannot be taken as evidence for neoteny unless confirmed at later stages of lungfish life history, which are yet to be studied.
EVOLUTION OF DAILY TORPOR AND HIBERNATION IN BIRDS AND MAMMALS: IMPORTANCE OF BODY SIZE
Authors: Geiser Fritz
Published: June 2007

1. The evolution of hibernation and daily torpor in mammals and birds remains a controversial subject. The original view was that use of torpor reflects a primitive thermoregulation, as it occurs in ancestral groups of mammals.

2. This view is no longer widely supported. However, the interpretation of a polyphyletic derivation of torpor also has been challenged because of the astonishing similarity of torpor patterns among various orders and even the two classes.

3. A recent argument is that mutations required for torpor and hibernation are unlikely to occur simultaneously and that torpor must be plesiomorphic (ancestral), although it is not functionally primitive. Homeothermy is interpreted as a loss of the ability to enter torpor in those groups that could survive without the requirement of heterothermic periods for energy conservation.

4. Interestingly, while torpor in mammals occurs in the phylo‐genetically old groups, lending support to the hypothesis of an ancestral derivation of torpor, the opposite is the case for birds. Modern bird groups and ancestral mammal groups contain mainly small species that often rely on fluctuating food supply, whereas modern mammalian orders and ancient bird orders contain the largest species with low energy requirements for maintenance and thermoregulation.

5. It is, therefore, possible that not phylogenetic position but size and diet determine the occurrence of heterothermy. Moreover, because endothermy and torpor in birds has apparently evolved separately from that in mammals and because it is possible that daily torpor and hibernation represent two distinct torpor patterns that evolved separately, a convergent evolution of torpor in endotherms cannot be excluded.