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1.
Stiffler DF Talbot CR 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(7):505-509
Oxygen consumption was measured in five Dermophis mexicanus and averaged (±SEM) 0.047 ± 0.004 ml O2 g−1 h−1. Carbon dioxide production averaged 0.053 ± 0.005 ml CO2 g−1 h−1 in the same five animals 1 week later. This metabolic rate is similar to metabolic rates of other Gymnophionans but lower
than metabolic rates reported for Anurans and Urodeles. Total nitrogen excretion averaged 1.37 μmol N g−1 h−1 which is higher than that found for other amphibians. Of this, 82.5% (1.13 μmol N g−1 h−1) was in the form of urea while 17.5% (0.24 μmol N g−1 h−1) was in the form of NH3 + NH+
4. Such ureotelism is typical of terrestrial amphibians like D. mexicanus. Osmotic water flux averaged 0.0193 ml g−1 h−1 in control (sham injected) animals and was not significantly altered by injection of either arginine vasotocin or mesotocin.
This osmotic flux is similar to osmotic fluxes found for other terrestrial amphibians. The combined data suggest that metabolism
in D. mexicanus is, like most other Gymnophionans, lower than other amphibians. The high rates of nitrogen (especially urea) excretion suggests
that this fossorial animal accumulates urea like other burrowing amphibians.
Accepted: 27 June 2000 相似文献
2.
Effects of sulfur containing amino acids on iron and nitric oxide stimulated catecholamine oxidation 总被引:3,自引:1,他引:2
Summary. Taurine is a free amino acid found in high concentrations in tissues containing catecholamines. The ability of taurine and
its metabolic precursors to inhibit or stimulate catecholamine oxidation and subsequent quinone formation was examined. Ferric
chloride was used as the catalyzing agent to stimulate L-dopa or norepinephrine oxidation and NO donors were also examined
for their actions to stimulate quinone formation. Taurine attenuated iron-stimulated quinone formation from catecholamines
suggesting that it may function as an endogenous antioxidant. Several other sulfur-containing amino acids (homocysteic acid,
cysteine sulfinic acid and SAM) were found to inhibit catecholamine oxidation. Among other amino acids tested, homocysteine
had biphasic effects; attenuating L-dopa oxidation catalyzed by ferric chloride and potentiating norepinephrine's oxidation
catalyzed by both ferric chloride and sodium nitroprusside (SNP). Homotaurine and homocysteine (1 or 10 mM) greatly stimulated
SNP-induced norepinephrine oxidation. Homotaurine potentiated quinone formation in the presence of ferric iron and this effect
was attenuated by desferroxamine. In order to exclude a possible NO/iron interaction in SNP's oxidizing action, SIN-1 chloride,
a specific NO-donor, was tested as an oxidizing agent. The failure of desferroxamine or taurine to attenuate SIN-1 oxidation
of norepinephrine suggests that peroxynitrite-mediated oxidation was likely the dominant mechanism. Our results show that
endogenous sulfur containing amino acids, like taurine, could serve a protective role to reduce cellular damage associated
with both NO and metal-stimulated catecholamine oxidation.
Received August 20, 2001 Accepted October 10, 2001 相似文献
3.
S. F. Perry K. M. Gilmour C. M. Wood P. Pärt P. Laurent P. J. Walsh 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(6):461-472
Simultaneous measurements of cardio-respiratory variables, oxygen uptake and whole body urea/ammonia/tritiated water effluxes
were performed on cannulated gulf toadfish, Opsanus beta, before and after intra-arterial injection of the vasoactive agents, adrenaline, isoproterenol and arginine vasotocin. These
experiments were conducted to test the hypothesis that the phenomenon of pulsatile urea excretion might reflect sudden changes
in the general diffusive properties of the gill for solute transfer. Injection of isoproterenol (final nominal circulating
level = 10−6 mol l−1), was used as a tool to maximise the diffusive and perfusive conditions for branchial solute transfer. This protocol caused
a pronounced reduction in arterial blood pressure, an elevation of cardiac frequency and associated increases in whole body
urea and tritiated water effluxes; ammonia excretion and oxygen uptake were unaffected. Injection of adrenaline (final nominal
circulating level=10−6 mol l−1), caused a significant increase in arterial blood pressure and a tachycardia, yet nitrogen excretion and oxygen uptake were
unaffected. Injection of arginine vasotocin, caused a dose-dependent (final nominal circulating levels = 10−11–10−9 mol l−1) increase in arterial blood pressure without affecting cardiac or ventilation frequency. At the two higher concentrations,
arginine vasotocin caused large and transient increases in urea excretion without significantly affecting ammonia, water or
oxygen fluxes. These results suggest that increased gill diffusive or perfusive conductance, while capable of augmenting urea
efflux, cannot fully explain the sudden and massive increases in urea transfer associated with pulsatile urea excretion in
toadfish. It is suggested that pulsatile urea excretion in this species may reflect a specific enhancement of urea excretion
under the control of the neurohypophyseal hormone, arginine vasotocin.
Accepted: 21 April 1998 相似文献
4.
Summary. Taurine as well as tauret (retinyliden taurine) levels were measured in locust Locusta migratoria compound eyes. HPLC measurements revealed relatively low taurine levels (1.9 ± 0.16 mM) in dark-adapted eyes. Glutamate,
aspartate and glycine levels were 2.0 ± 0.2, 2.7 ± 0.4 and 3.0 ± 0.37 mM, respectively, while GABA was present only in trace
amounts. After about 4 h of light adaptation at 1500–2000 lx, amino acid levels in the compound eye were as follows: taurine,
1.8 ± 0.17 mM; glutamate, no change at 2.1 ± 0.2 mM; aspartate sharply increased to 4.7 ± 0.7 mM; glycine slightly decreased
to 2.8 ± 0.3 mM; and GABA trace levels. In the compound eye of locust Locusta migratoria, the existence of endogenous tauret in micro-molar range was established. In the dark, levels were several times higher compared
with compound eye after light adaptation 1500 lx for 3 h, as estimated by TLC in combination with spectral measurements. Existence
of tauret in compound eye is of special interest because in the compound eye, rhodopsin regeneration is based on photoregeneration. 相似文献
5.
Dietary taurine enhances cholesterol degradation and reduces serum and liver cholesterol concentrations in rats fed a high-cholesterol diet 总被引:1,自引:0,他引:1
Summary. The effect of taurine on hypercholesterolemia induced by feeding a high-cholesterol (HC) diet (10 g/kg) to rats was examined.
When taurine was supplemented to HC for 2 wk, serum total cholesterol significantly decreased and serum HDL-cholesterol increased
compared with the HC diet group. In the hypercholesterolemic rats fed the HC diet, the excretion of fecal bile acids and hepatic
cholesterol 7α-hydroxylase (CYP7A1) activity and its mRNA level increased significantly, and the supplementation of taurine further enhanced
these indexes, indicating an increase in cholesterol degradation. Agarose gel electrophoresis revealed that, in hypercholesterolemic
rats fed the HC diet, the serum level of the heavier VLDL increased significantly, but taurine repressed this increase and
normalized this pattern. Significant correlations were observed between the time-dependent increase of CYP7A1 gene expression
and the decrease of blood cholesterol concentration in rats fed the HC diet supplemented with taurine. These results suggest
that the hypocholesterolemic effects of taurine observed in the hypocholesterolemic rats fed the HC diet were mainly due to
the enhancement of cholesterol degradation and the excretion of bile acid.
Received December 4, 2001 Accepted January 2, 2002 Published online September 10, 2002
Acknowledgment This work was supported by a grant of Taisho Pharmaceutical Co., Ltd (Japan). We thank J. I. Gordon for their generous gifts
of cDNAs.
Authors' address: Dr. Hidehiko Yokogoshi, School of Food and Nutritional Sciences, The University of Shizuoka, Shizuoka 4228526, Japan, E-mail:
yokogosi@u-shizuoka-ken.ac.jp 相似文献
6.
Mühling J Fuchs M Fleck C Sablotzki A Krüll M Dehne MG Gonter J Weiss S Engel J Hempelmann G 《Amino acids》2002,22(1):39-53
Summary. The objective of this study was to determine the effects of arginine, L-alanyl-L-glutamine (Ala-Gln) or taurine on polymorphonuclear
leucocyte (PMN) free amino acid profiles, superoxide anion (O2
−) generation, hydrogen peroxide (H2O2) formation and released myeloperoxidase activity (MPO). Arginine led to significant increases in PMN arginine, ornithine,
citrulline, aspartate, glutamate and alanine concentrations as well as increased H2O2-generation and MPO activity while O2
−-formation was decreased. Ala-Gln caused significant increases in PMN free glutamine, alanine, asparagine, aspartate, glutamate,
ornithine, arginine, serine and glycine concentrations and increased PMN immune functions. Taurine significantly increased
PMN free taurine profiles, reduced PMN neutral amino acid content and decreased H2O2- and O2
−-formation while MPO was increased. Altogether, the pharmacological regimens which enhance the supply of arginine, Ala-Gln
or taurine in whole blood significantly affect PMN "susceptible free amino acid pool". This may be one of the determinants
in PMN nutrition considerably influencing PMN immune functions.
Received October 25, 2000 Accepted March 21, 2001 相似文献
7.
Summary. The aim of the present study was to measure MPO activity in PMN leukocytes after endotoxin administration, and to compare
the levels of NO2
− competing with taurine for reaction with HOCl. Furthermore we aimed to determine TauCl levels, a product of MPO–H2O2–Halide system, and to evaluate anti-inflammatory properties of PMN in endotoxemia. In addition, our second objective was
to investigate the effect of taurine, an antioxidant amino acid, on anti-bactericidal and anti-inflammatory functions of PMN
after administration of endotoxin together with taurine.
All experiments were performed with four groups (control, taurine, endotoxemia, and taurine plus endotoxin) of ten guinea
pigs. After endotoxin administration (4 mg/kg), MPO activities increased and taurine levels decreased. Therefore levels of
TauCl, NO2
•− increased. We observed the effects of taurine as conflicting. When taurine was administrated alone (300 mg/kg), all of these
parameters decreased.
Consequently, we suggested that taurine is influential in infected subjects but not on healthy ones as an antioxidative amino
acid. In addition, we believe that in vivo effects of taurine may differ from those in vitro depending on its dosage. 相似文献
8.
Farriol M Venereo Y Rosselló J Gomez P Palao R Orta X Segovia-Silvestre T 《Amino acids》2002,23(4):441-445
Summary. This study determines the effects of taurine (Tau) on phagocytosis of polymorphonuclear neutrophils (PMN) isolated from normal
subjects (n = 41) and severely burned patients (n = 20). Phagocytosis was measured by nitroblue of tetrazolium (NBT) reduction
in samples with and without latex bead stimulation. Taurine was added at doses of 0.2, 0.4, 0.8 and 1.6 mM to stimulated samples.
In control cells there were statistically significant increases in phagocytosis after addition of Tau 0.8 mM and 1.6 mM to
as compared to samples without Tau addition (295 ± 23% and 330 ± 35% vs. 248 ± 18%; mean ± S.E.; p < 0.05). A statistically
significant increase in phagocytosis was observed in cells from the burned population after addition of Tau 1.6 mM (288 ±
38% vs. 198 ± 13%; mean ± S.E.; p < 0.05). No changes in phagocytosis were found in cells from a subgroup of burn patients
(n = 13) followed over 7, 15 and 21 days. These results indicate that taurine supplementation in vitro at doses of 0.8 to
1.6 mM improves the phagocytic capacity of neutrophils in healthy subjects and in patients with severe burn injury, mainly
when neutrophil function is unaltered.
Received December 17, 2001 Accepted January 17, 2002 Published online August 30, 2002
Authors' address: Dr. Mireia Farriol, Centre d'Investigacions Bioquímicas i Biología Molecular (CIBBIM), Hospital General Vall d'Hebron Passeig
Vall d'Hebron 119-129, E-08035 Barcelona, Spain, Fax: 34-93-2746831, E-mail: farriol@hg.vhebron.es 相似文献
9.
Active excretion of ammonia across the gills of the shore crab Carcinus maenas and its relation to osmoregulatory ion uptake 总被引:1,自引:0,他引:1
D. Weihrauch W. Becker U. Postel S. Riestenpatt D. Siebers 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(5):364-376
The mechanism of transbranchial excretion of total ammonia of brackish-water acclimated shore crabs, Carcinus maenas was examined using isolated, perfused gills. Applying physiological gradients of NH4Cl (100–200 μmol · l−1) directed from the haemolymph space to the bath showed that the efflux of total ammonia consisted of two components. The
saturable component (excretion of NH4
+) greatly exceeded the linear component (diffusion of NH3). When an outwardly directed gradient (200 μmol · l−1) was applied, total ammonia in the perfusate was reduced by more than 50% during a single passage of saline through the gill.
Effluxes of ammonia along the gradient were sensitive to basolateral dinitrophenol, ouabain, and Cs+ and to apical amiloride. Acetazolamide (1 mmol · l−1 basolateral) or Cl−-free conditions had no substantial effects on ammonia flux, which was thus independent of both carbonic anhydrase mediated
pH regulation and osmoregulatory NaCl uptake. When an inwardly directed gradient (200 μmol · l−1) was employed, influx rates were about 10-fold smaller and unaffected by basolateral ouabain (5 mmol · l−1) or dinitrophenol (0.5 mmol · l−1). Under symmetrical conditions (100 μmol · l−1 NH4Cl on both sides) ammonia was actively excreted against the gradient of total ammonia, which increased strongly during the
experiment and against the gradient of the partial pressure of NH3. The active excretion rate was reduced to 7% of controls by basolateral dinitrophenol (0.5 mmol · l−1), to 44% by basolateral ouabain (5 mmol · l−1), to 46% by Na+-free conditions and to 42% by basolateral Cs+ (10 mmol · l−1), indicating basolateral membrane transport of NH4
+ via the Na+/K+-ATPase and K+-channels and a second active, apically located, Na+ independent transport mechanism of NH4
+. Anterior gills, which are less capable of active ion uptake than posterior gills, exhibited even increased rates of active
excretion of ammonia. We conclude that, under physiological conditions, branchial excretion of ammonia is a directed process
with a high degree of effectiveness. It even allows active extrusion against an inwardly directed gradient, if necessary.
Accepted: 11 March 1998 相似文献
10.
H. Ramløv 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(3):224-235
The microclimate in the habitat of the New Zealand alpine weta Hemideina maori is very variable with winter temperatures down to −6 °C under the rocks where the insects are found. Subfreezing temperatures
may in winter prevail for up to 17 days but diurnal cycles of freezing and thawing are common, as is also the case in summer.
Rates of temperature change can be very high and up to −7.20 °C/h. During winter, humidity was high for extended periods ranging
from 70% to 100% relative humidity (RH). In the summer, humidity ranged from 30% RH during the day to 100% RH at night. The
supercooling point of the haemolymph was approximately −8 °C year round, caused by a heat labile substance. The supercooling
point of the haemolymph of an insect of the same genus, Hemideina femorata not regularly exposed to subfreezing temperatures, was ca. −16.5 °C. Thermal hysteresis was not detected in the haemolymph
of H. maori. Haemolymph osmolality varied from 380 mOsm (summer) to 700 mOsm (winter). Body water content was ca. 75% all year round.
Total concentrations of sodium, potassium and chloride in haemolymph varied from 170 mM (winter) to 250 mM (summer). The total
concentration of free amino acids varied from 58 mM (summer) to 263 mM (winter). This variation was mostly due to proline
which varied from ca. 15 mM (summer) to ca. 100 mM (winter). The freeze-tolerant weta H. maori is exposed to a highly variable and cold environment all year round and several properties of its haemolymph composition
can be attributed to these climatic conditions, e.g. the presence of ice-nucleating agents and an increase in the concentration
of proline during cold hardening in the autumn.
Accepted: 22 February 1999 相似文献
11.
Characteristics of dipeptide transport in pig jejunum in vitro 总被引:4,自引:0,他引:4
Winckler C Breves G Boll M Daniel H 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(7):495-500
Characteristics of dipeptide transport in pig jejunum were investigated in vitro by applying the Ussing-chamber technique
and mucosal uptake studies. Addition of both glycyl-l-glutamine and glycyl-l-sarcosine (20 mmol · l−1) to the mucosal buffer solution significantly increased the short-circuit current by 2.60 ± 0.15 and 1.57 ± 0.20 μeq · cm−2 · h−1, respectively. Concentration-dependent changes in short-circuit current followed Michaelis-Menten kinetics with similar affinity
constants for both dipeptides. From unidirectional flux rates for radiolabelled glycyl-l-sarcosine, a net flux rate for glycyl-l-sarcosine of 49.8 ± 6.7 nmol · cm−2 · h−1 was calculated. In mucosal uptake experiments, the apical influx of 14C-labelled glycyl-l-sarcosine into isolated porcine mucosa was pH dependent and significantly inhibited by glycyl-l-glutamine. Moreover, RT-PCR studies with primers derived from rabbit PepT1 identified two PCR fragments of identical size
to rabbit PepT1 from pig intestinal mRNA preparations. In conclusion, our studies revealed key features of mammalian intestinal
peptide transporters and give evidence for a PepT1-like transporter in the pig jejunum that could significantly contribute
to the overall amino acid absorption from the gut.
Accepted: 30 June 1999 相似文献
12.
Herbert R. L. Drouin 《European biophysics journal : EBJ》1999,28(7):600-604
A new ion-selective liquid membrane microelectrode, based on the neutral carrier 1,1′-bis(2,3-naphtho-18-crown-6), is described
that shows the dependence of EMF on the activity of divalent putrescine cations a
Put, with the linear slope s
Put = 26 ± 3 mV/decade (mean ± SD, N = 18), in the range 10−4–10−1 M at 25 ± 1 °C. Values of potentiometric putrescine cation selectivity coefficients of logK
Pot
Put
j
(mean ± SD, N) are obtained by the separate solution method for the ions K+ (1.0 ± 0.4, 10), Na+ (−1.2 ± 0.4, 8), Ca2+ (−2.3 ± 0.5, 10) and Mg2+ (−2.5 ± 0.5, 7). The microelectrode can be applied for the direct analysis of the activities of free divalent putrescine
cations in the range 5 × 10−4 to 10−1 M in an extracellular ionic environment. Established analytical methods, e.g. high performance liquid chromatography, determine
the total concentration of the derivatives of free and bound putrescine.
Received: 20 December 1998 / Revised version: 7 May 1999 / Accepted: 27 May 1999 相似文献
13.
Summary. This study investigates the relationship between changes in plasma sodium and changes in amino acid levels in a patient with
post-traumatic sepsis and prolonged critical illness. Ninety-two consecutive measurements were performed at regular intervals
over a period of many weeks; these consisted in the determination of full amino-acidograms, plasma sodium and complementary
variables. A unique, highly significant inverse correlation between taurine and plasma sodium was found (r2 = 0.48, p < 0.001). All other amino acids were unrelated, or much more weakly related, to sodium. Taurine was also strongly
and directly related to phosphoethanolamine, glutamate and aspartate. Changes in sodium and in levels of these amino acids
explained up to 86% of the variability of taurine. Besides, levels of these amino acids maintained a high degree of co-variation,
remaining reciprocally related one to each other, directly, with r2 ranging between 0.33 and 0.59 (p < 0.001 for all). There were similar findings for β-alanine, which however was measured inconsistently. These data provide gross clinical evidence of a specific link binding
plasma sodium and taurine levels, and may be consistent with occurrence of opposite and interdependent shifts of sodium and
taurine between intravascular and extravascular space, to maintain osmoregulation. Co-variation of taurine with the other
amino acids may be related to the same phenomenon, and/or to similarities in transport systems and chemical structure, or
true metabolic interactions.
Received April 16, 2002 Accepted June 19, 2002 Published online November 14, 2002
RID="*"
ID="*" Presented at the 7th International Congress on Amino Acids and Proteins, Vienna (Austria), August 6–10, 2001.
Acknowledgements The authors acknowledge the kind assistance of Mr. Maurizio Cianfanelli, from the Catholic University School of Medicine,
Rome, Italy.
Authors' address: Dr. Carlo Chiarla, Via Augusto Tebaldi, 19, I-00168 Roma, Italy, E-mail: carlo.chiarla@rm.unicatt.it 相似文献
14.
Melike Bor Ozden Ozkur Filiz Ozdemir Ismail Turkan 《Plant Molecular Biology Reporter》2009,27(4):518-525
Myrosinase (EC 3.2.1.147) catalyzes cleavage of glucosinolates, which consist of a thioglucoside moiety linked to amino acid-derived
side chains. Myrosinase activity and expression profiles were investigated together with glucosinolate contents in Capparis ovata (caper) in order to characterize the glucosinolate–myrosinase system. The desulfoglucosinolates—glucocapparin, glucoiberin,
progoitrin, epiprogoitrin, sinigrin, gluconapin, glucosinalbin, and glucobrassicin—were extracted and quantified from leaves,
seeds, flowers, flower buds, and young shoots. The major desulfoglucosinolate was glucocapparin, which accumulated to values
of 39.35 ± 0.09 and 25.56 ± 0.11 μmol g−1 dry weight in seed and leaf extracts, respectively. Myrosinase has high activity in caper seeds, leaves, flowers, and flower
bud tissues having the highest total activities in seed extracts (79.23 ± 0.18 U). However, specific activities were the highest
in flower bud extracts (200.44 ± 0.09 U mg−1 protein). The myrosinase protein migrated as a single band with a molecular weight of 65 kDa on sodium dodecyl sulfate polyacrylamide
gel electrophoresis and on Western blots probed with the myrosinase-specific 3D7 antibodies. Native gel electrophoresis revealed
two putative myrosinase isoenzymes in seeds, leaves, and flower tissues. The caper homolog of the Arabidopsis thaliana TGG1 gene was differentially expressed in seeds, leaves, flowers, and flower buds with the highest expression levels in leaves
and flower bud tissues. 相似文献
15.
Nigel J. Adams Berry Pinshow Leonard Z. Gannes 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(6):444-450
We used tritium-labeled water to measure total body water, water influx (which approximated oxidative water production) and
water efflux in free-flying tippler pigeons (Columba livia) during flights that lasted on average 4.2 h. At experimental air temperatures ranging from 18 to 27 °C, mean water efflux
by evaporation and excretion [6.3 ± 1.3 (SD) ml · h−1, n = 14] exceeded water influx from oxidative water and inspired air (1.4 ± 0.7 ml · h−1, n = 14), and the birds dehydrated at 4.9 ± 0.9 ml · h−1. This was not significantly different from gravimetrically measured mass loss of 6.2 ± 2.1 g · h−1 (t = 1.902, n = 14, P>0.05). This flight-induced dehydration resulted in an increase in plasma osmolality of 4.3 ± 3.0 mosmol · kg−1 · h−1 during flights of 3–4 h. At 27 °C, the increase in plasma osmolality above pre-flight levels (ΔP
osm = 7.6±4.29 mosmol · kg−1 · h−1, n = 6) was significantly higher than that at 18 °C (ΔP
osm = 0.83±2.23 mosmol · kg−1 · h−1, (t = 3.43, n = 6, P < 0.05). Post-flight haematocrit values were on average 1.1% lower than pre-flight levels, suggesting plasma expansion. Water
efflux values during free flight were within 9% of those in the one published field study (Gessaman et al. 1991), and within
the range of values for net water loss determined from mass balance during wind tunnel experiments (Biesel and Nachtigall
1987). Our net water loss rates were substantially higher than those estimated by a simulation model (Carmi et al. 1992) suggesting
some re-evaluation of the model assumptions is required.
Accepted: 8 April 1997 相似文献
16.
The role of taurine added to pulmonary reperfusion solutions in isolated guinea pig lungs 总被引:1,自引:0,他引:1
Summary. An experimental comparative study on isolated guinea pig-lungs has been undertaken to determine the probable beneficial effects
of adding taurine to pulmonary reperfusion solutions in lung ischemia-reperfusion. 20 guinea pigs were used. The isolated
lungs (n = 10 in each group) previously being perfused by oxygenated Krebs-Henseleit solution were put in normothermic ischemic
conditions. After 3 hours of normothermic ischemia the lungs were reperfused (with Krebs-Henseleit solution in the control
group, Krebs-Henseleit solution plus taurine 10−2 M in the experiment group) for 20 minutes. Pulmonary artery pressures, tissue malondialdehyde (MDA) and glutathione (GSH)
levels were measured before and after the ischemic period and also at the end of reperfusion. Malondialdehyde and glutathione
levels of the pefusate were measured before ischemic period and at the end of reperfusion. An electron microscopic analysis
was performed on the lung tissues before and after the ischemic period and also at the end of reperfusion. Decreased pulmonary
artery pressure, tissue perfusate MDA levels and increased perfusate GSH levels were observed in taurine added group. Electron
microscopic evaluation supported our findings indicating preservation of lamellar bodies of type II pneumocytes. It is concluded
that taurine may play an important role in protecting tissue against ischemia-reperfusion injury by functioning as an antioxidant.
Received May 16, 2001 Accepted September 6, 2001 相似文献
17.
Schröder B Vössing S Breves G 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(7):487-494
From various in vivo and in vitro studies it has been shown that the rumen represents a significant site of Ca2+ absorption in sheep and goats. It was the aim of the present study to further characterize the underlying mechanisms. Unidirectional
flux rates of Ca2+ across rumen wall epithelia of sheep were measured in vitro by applying the Ussing-chamber technique in the absence of electrochemical
gradients. Under these conditions, significant Ca2+ net flux rates (Jnet) clearly indicate the presence of active mechanisms for Ca2+ transport. Short chain fatty acids (SCFAs) caused highest stimulation of Ca2+ Jnet (6.3 ± 1.9 nmol · cm−2 · h−1) when used as a mixture of acetate, proprionate and butyrate in physiological proportions (36, 15, 9 mmol · l−1, respectively). The effect of 30 mmol · l−1 butyrate (3.2 ± 0.6 nmol · cm−2 · h−1) was higher than respective amounts of propionate and acetate (0.6 ± 0.8 nmol · cm−2 · h−1 and 0.9 ± 0.8 nmol · cm−2 · h−1, respectively). Eliminating SCFAs resulted in Ca2+ Jnet of 0.4 ± 1.1 nmol . cm−2 . h−1. Addition of Ca channel blocker verapamil (mucosal 1 mmol · l−1) had no significant effect on SCFA-stimulated Jnet of Ca2+, whereas application of Na+/H+ inhibitor amiloride (mucosal 1 mmol · l−1) further enhanced the Ca2+ Jnet by >65%. The Ca2+-pump inhibitor vanadate had no significant effect on Jnet of Ca2+. Dietary Ca depletion enhanced calcitriol plasma concentrations but had no effect on active Ca2+ absorption across the rumen wall of sheep. In addition, no effect on active Ca2+ absorption could be observed during early lactation. In conclusion, there is clear evidence for the rumen as a main site
for active Ca2+ absorption in sheep. Our results suggest the presence of a Ca2+/H+ exchange mechanism in the apical membrane of rumen epithelial cells which depends on SCFA absorption and which does not seem
to be under the control of calcitriol. Basolateral Ca2+ extrusion occurs independently from Ca2+-pump activity and may be accomplished via Na+/Ca2+ exchange.
Accepted: 29 June 1999 相似文献
18.
Potential of the seaweed Gracilaria lemaneiformis for integrated multi-trophic aquaculture with scallop Chlamys farreri in North China 总被引:2,自引:0,他引:2
Yuze Mao Hongsheng Yang Yi Zhou Naihao Ye Jianguang Fang 《Journal of applied phycology》2009,21(6):649-656
In this study the red alga, Gracilaria lemaneiformis, was cultivated with the scallop Chlamys farreri in an integrated multi-trophic aquaculture (IMTA) system for 3 weeks at the Marine Aquaculture Laboratory of the Institute
of Oceanology, Chinese Academy of Sciences (IOCAS) in Qingdao, Shandong Province, North China. The nutrient uptake rate and
nutrient reduction efficiency of ammonium and phosphorus from scallop excretion were determined. The experiment included four
treatments each with three replicates, and three scallop monoculture systems served as the control. Scallop density (407.9 ± 2.84 g
m−3) remained the same in all treatments while seaweed density differed. The seaweed density was set at four levels (treatments
1, 2, 3, 4) with thallus wet weight of 69.3 ± 3.21, 139.1 ± 3.80, 263.5 ± 6.83, and 347.6 ± 6.30 g m−3, respectively. There were no significant differences in the initial nitrogen and phosphorus concentration between each treatment
and the control group (ANOVA, p > 0.05). The results showed that at the end of the experiment, the nitrogen concentration in the control group and treatment
1 was significantly higher than in the other treatments. There was also a significant difference in phosphorus concentration
between the control group and the IMTA treatments (ANOVA, p < 0.05). Growth rate, C and N content of the thallus, and mortality of scallop was different between the IMTA treatments.
The nutrient uptake rate and nutrient reduction efficiency of ammonium and phosphorus changed with different cultivation density
and time. The maximum reduction efficiency of ammonium and phosphorus was 83.7% and 70.4%, respectively. The maximum uptake
rate of ammonium and phosphorus was 6.3 and 3.3 μmol g−1 DW h−1. A bivalve/seaweed biomass ratio from 1:0.33 to 1:0.80 (treatments 2, 3, and 4) was preferable for efficient nutrient uptake
and for maintaining lower nutrient levels. Results indicate that G. lemaneiformis can efficiently absorb the ammonium and phosphorus from scallop excretion and is a suitable candidate for IMTA. 相似文献
19.
Bradshaw FJ Bradshaw SD 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2001,171(1):59-67
A nitrogen balance feeding trial was carried out with the marsupial honey possum, Tarsipes rostratus, using four pollen-honey diets varying in nitrogen content from 9.4 mg · g−1 to 2.3 mg · g−1 dry matter. The dietary maintenance nitrogen requirement (MNR) was determined by regression analysis as 89 ± 21 mg N · kg−0.75 · day−1 and the truly digestible MNR was 79 mg N · kg−0.75 · day−1.. Regressing nitrogen balance on daily nitrogen intake separately for ten males and seven females revealed that the slopes
of the fitted lines did not vary significantly, but the difference in the intercepts approached significance. This suggests
that the MNR for females may be lower than that of males. The nitrogen digestibility of the diet was 76% and the biological
value (BV) was 58%. A comparison of the MNR of the honey possum with that of other marsupials shows that it is indeed much
lower than that of herbivorous macropodid marsupials and is close to that of the sap- and gum-feeding sugar glider, Petarurus breviceps. The endogenous urinary nitrogen excretion (EUN) of the honey possum was 42 mg N · kg−0.75 · day−1 and a regression analysis with other published data showed that the EUN per unit basal heat production is significantly lower
than that of eutherian mammals. Measurements of the actual feeding rates of animals in the field, taken together with the
low MNR, do not lend support to the hypothesis that the honey possum exhibits a reduced rate of reproduction due to a deficiency
in dietary nitrogen. It is possible that the quality of nitrogen provided by pollen, as reflected in its composition of essential
amino acids, may be a limiting factor.
Accepted: 15 September 2000 相似文献
20.
Biomass and metabolism of zooplankton in the Bransfield Strait (Antarctic Peninsula) during austral spring 总被引:1,自引:1,他引:0
Zooplankton biomass (as dry weight), respiration and ammonia excretion were studied in three different size classes (200–500,
500–1000 and >1000 μm) in the Bransfield Strait during December 1991. Average mesozooplankton biomass was 86.45 ± 56.74 mg · dry weight · m−2, which is in the lower range of the values cited in the literature for polar waters. Higher biomass was observed in the Weddell
water. The small size fraction accounted for about 50% of total biomass while the largest one represented 35%. Rather high
metabolic rates were found, irrespective of whether the organisms were incubated in the presence of food. No significant differences
were observed in mass specific respiration and ammonia excretion rates between different temperatures of incubation (0.2–2.3°C)
and between the size classes studied. Because of the very low biomass values observed, the metabolic requirements of mesozooplankton
during December represented a small fraction of the primary production.
Accepted: 5 September 1998 相似文献