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1.
Jing-Wei Xiong Liping Zhu Xuanmao Jiao Shu-Sen Liu 《Biochimica et Biophysica Acta (BBA)/General Subjects》2010
Background
One of the central debates in membrane bioenergetics is whether proton-dependent energy coupling mechanisms are mediated exclusively by protonic transmembrane electrochemical potentials, as delocalized pmf, ΔµH+, or by more localized membrane surface proton pathways, as interfacial pmf, ΔµHS.Methods
We measure ?pHS in rat liver mitoplasts energized by respiration or ATP hydrolysis by inserting pH sensitive fluorescein-phosphatidyl-ethanolamine(F-PE) into mitoplast surface.Results
In the presence of rotenone and Ap5A, succinate oxidation induces a bi-phasic interfacial protonation on the mitoplast membranes, a fast phase followed by a slow one, and an interfacial pH decrease of 0.5 to 0.9 pH units of mitoplast with no simultaneous pH changes in the bulk. Antimycin A, other inhibitors or uncouplers of mitochondrial respiration prevent the decrease of mitoplast ?pHS, supporting that ΔµHS is dependent and controlled by energization of mitoplast membranes. A quantitative assay of ATP synthesis coupled with ?pHS of mitoplasts oxidizing succinate with malonate titration shows a parallel correlation between ATP synthesis, State 4 respiration and ?pHS, but not with ?ΨE.General Significance
Our data substantiate ?pHS as the primary energy source of pmf for mitochondrial ATP synthesis. Evidence and discussion concerning the relative importance and interplay of ?pHS and ?ΨE in mitochondrial bioenergetics are also presented. 相似文献2.
Specific mgi mutations in the α, β or γ subunits of the mitochondrial F1-ATPase have previously been found to suppress ρ0 lethality in the petite-negative yeast Kluyveromyces lactis. To determine whether the suppressive activity of the altered F1 is dependent on the F0 sector of ATP synthase, we isolated and disrupted the genes KlATP4, 5 and 7, the three nuclear genes encoding subunits b, OSCP and d. Strains disrupted for any one, or all three of these genes are respiration deficient and have reduced viability. However a strain devoid of the three nuclear genes is still unable to lose mitochondrial DNA, whereas a mgi mutant with the three genes inactivated remains petite-positive. In the latter case, ρ0 mutants can be isolated, upon treatment with ethidium bromide, that lack six major F0 subunits, namely the nucleus-encoded subunits b, OSCP and d, and the mitochondrially encoded Atp6, 8 and 9p. Production of ρ0 mutants indicates that an F1-complex carrying a mgi mutation can assemble in the absence of F0 subunits and that suppression of ρ0 lethality is an intrinsic property of the altered F1 particle. Received: 7 April 1998 / Accepted: 10 June 1998 相似文献
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4.
Antibodies against the main urinary metabolite of PGF2α in the human, 5α,7α-dihydroxy-11-ketotetranorprosta-1,16-dioic acid, were raised in rabbits. The compound was coupled selectively in the ω position to bovine serum albumin prior to injection. The resulting antibodies did not distinguish between tetranor compounds varying only in structure at the ω carbon, and thus the assay could be used also for other metabolites of PGF2α, e.g. the main urinary metabolite in the guinea pig, 5α,7α-dihydroxy-11-ketotetranorprostanoic acid. Labeled ligands for the assays were prepared either by injection of |17,18-3H|-PGF2α into humans after several days' treatment with indomethacin, or by incubation of |17,18-3H|-15-keto-13,14-dihydro-PGF2α with mitochondria from rat liver. The sensitivity of the assay was 10 pg or 4 pg with these two preparations, respectively.The assay was employed for a number of measurements: normal daily excretion in a number of humans; excretion of urinary metabolites during treatment with prostaglandin synthetase inhibitors in human subjects, or after intravenous injection of PGF2α; excretion during human pregnancy; and prostaglandin production in the guinea pig during normal estrous cycles and pregnancies and after estrogen treatment.The results of these studies were in several cases compared to similar measurements earlier performed using mass spectrometric methods, and were found to agree well. Thus, this radioimmunoassay provides a simple and accurate method for estimating prostaglandin production, particularly suitable for long-term studies and for cases where repeated blood sampling must be avoided. 相似文献
5.
The rate of photosynthetic electron transport measured in the absence of ADP and Pi is stimulated by low levels of Hg2+ or Ag+ (50% stimulation ≈ 3 Hg2+ or 6 Ag+/100 chlorophyll) to a plateau equal to the transport rate under normal phosphorylating conditions (i.e. +ADP, +Pi). Chloroplasts pretreated in the light under energizing conditions with N-ethylmaleimide show a similar stimulation of non-phosphorylating electron transport. The stimulations of non-phosphorylating electron transport by Hg2+, Ag+ and N-ethylmaleimide are reversed by the CF1 inhibitor phlorizin, the CF0 inhibitor triphenyltin chloride, and can be further stimulated by uncouplers such as methylamine. The Hg2+ and N-ethylmaleimide stimulations, but not the Ag+ stimulation, are completely reversed by low levels of ADP (2 μM), ATP (2 μM), and Pi (400 μM). Ag+, which is a potent inhibitor of ATP synthesis, has little or no effect upon phosphorylating electron transport (+ADP, +Pi). Concomitant with the stimulations of non-phosphorylating electron transport by Hg2+, Ag+ and ADP + Pi, there is a decrease in the level of membrane energization (as measured by atebrin fluorescence quenching) which is reversed when the CF0 channel is blocked by triphenyltin. These results suggest that modification of critical CF1 sulfhydryl residues by Hg2+, Ag+ or N-ethylmaleimide leads to the loss of intra-enzyme coupling between the transmembrane protontransferring and the ATP synthesis activities of the CF0-CF1 ATP synthase complex. 相似文献
6.
Effect of prostaglandin F2α on propulsive activity of the isolated segmental colon of the guinea-pig
The effects of prostaglandin F2α (PGF2α) on propulsive activity in segments of isolated colon and on isolated strips of guinea-pig colon were investigated.Using experimental conditions under which spontaneous propulsive activity was negligible, PGF2α (5×10−8×1×10−6M), added to the bathing medium, increased propulsive activity in a concentration dependent manner. This increase of propulsive activity was abolished in the presence of atropine or tetrodotoxin (1×10−7g/ml).The contractions produced by PGF2α(5×10−7 − 1×10−5M) in isolated longitudinal and circular smooth muscle strips of guinea-pig colon were unaffected in the presence of atropine or tetrodotoxin (1×10−7g/ml).From these results it is concluded that under the conditions employed in this study propulsive activity stimulated by PGF2α may depend on the contractions of both muscle layers and stimulation of the peristalic reflex. 相似文献
7.
Krister Gréen Elisabeth Granström Marc Bygdeman Nils Wiqvist 《Prostaglandins & other lipid mediators》1976,11(4):699-711
The metabolism of tritium labeled 15-methyl-PGF2α, administered intra-amniotically, was studied in seven cases of mid-trimester abortion. The disappearance of the compound from the amniotic sac was a very slow process. A metabolite, dinor-15-methyl-PGF2α, was found in small amounts in the amniotic fluid and also in extracts of placenta and fetal liver, lung, and kidney. Plasma levels of 15-methyl-PGF2α in the maternal circulation were determined. 相似文献
8.
Prostaglandins (PG) of both the E and F series may serve as modulators of norepinephrine (NE) release from peripheral sympathetic neurons. We have studied the effects of PGE2 and PGF2α on the accumulation and release of 3H-NE in the CNS using synaptosomes isolated from rat hypothalami.The release of 3H-NE from synaptosomes superfused with Krebs-Ringer bicarbonate buffer was multiphasic with an initial fast release phase followed by a slower release. Raising KC1 concentration of the superfusion medium to 56mM during the slow release phase is known to stimulate 3H-NE release. PGE2 (1 × 10?6M) attenuated 3H-NE release during the fast phase and reduced the amount of 3H-NE released due to KC1 stimulation. At lower concentrations of PGE2 there was no change in the release profile. PGF2α was without effect on 3H-NE release at all concentrations tested.The accumulation of 3H-NE was significantly diminished by PGE2 at a concentration of 1 × 10?6M, while a lower concentration (1 × 10?7M) was ineffective. PGF2α had no effect on 3H-NE accumulation at all concentrations investigated. 相似文献
9.
A sensitive and relatively specific radioimmunoassay for 15 (S) 15 methyl prostaglandin F2α was used to determine the levels of the drug in amniotic fluid after it had been injected intra-amniotically for termination of second trimester pregnancy. The disappearance of the free acid (tham salt) and methyl ester of the prostaglandin analogue were similar. The results of this preliminary study suggest that the drug rapidly equilibrates in the fluid and this is followed by a slow removal from the amniotic sac. A comparison with a similar study with PGF2α, revealed that the analogue had a longer half-life in the amniotic fluid. 相似文献
10.
Quantitative assays for prostaglandins (PG) E1 and PGF1α are described using [3,3,4,4,5,6-2H6]labeled prostaglandins as carriers and methyl ester-O-methyloxime-acetate (PGE1) and methyl ester-acetate (PGF1α) derivatives for gas - liquid chromatography/mass spectrometric analysis. Thin-layer argentation chromatography was used to separate PGE1 from PGE2 and 13, 14-dihydro-PGE2. These latter compounds, which do not separate from PGE1 using conventional thin-layer chromatography or under the gas - liquid chromatographic conditions used, can significantly interfere with the quantitative analysis of PGE1. The method described prevents this interference and is therefore suitable for the accurate analysis of PGE1 in biological samples containing a high concentration of PGE2 and/or 13, 14-dihydro-PGE2. 相似文献
11.
Aims
We previously reported that fluvoxamine, a selective serotonin reuptake inhibitor with high affinity for the σ1-receptor (σ1R), ameliorates cardiac hypertrophy and dysfunction via σ1R stimulation. Although σ1R on non-cardiomyocytes interacts with the IP3 receptor (IP3R) to promote mitochondrial Ca2 + transport, little is known about its physiological and pathological relevance in cardiomyocytes.Main methods
Here we performed Ca2 + imaging and measured ATP production to define the role of σ1Rs in regulating sarcoplasmic reticulum (SR)-mitochondrial Ca2 + transport in neonatal rat ventricular cardiomyocytes treated with angiotensin II to promote hypertrophy.Key finding
These cardiomyocytes exhibited imbalances in expression levels of σ1R and IP3R and impairments in both phenylephrine-induced mitochondrial Ca2 + mobilization from the SR and ATP production. Interestingly, σ1R stimulation with fluvoxamine rescued impaired mitochondrial Ca2 + mobilization and ATP production, an effect abolished by treatment of cells with the σ1R antagonist, NE-100. Under physiological conditions, fluvoxamine stimulation of σ1Rs suppressed intracellular Ca2 + mobilization through IP3Rs and ryanodine receptors (RyRs). In vivo, chronic administration of fluvoxamine to TAC mice also rescued impaired ATP production.Significance
These results suggest that σ1R stimulation with fluvoxamine promotes SR-mitochondrial Ca2 + transport and mitochondrial ATP production, whereas σ1R stimulation suppresses intracellular Ca2 + overload through IP3Rs and RyRs. These mechanisms likely underlie in part the anti-hypertrophic and cardioprotective action of the σ1R agonists including fluvoxamine. 相似文献12.
William E Hoffman Marc L Leavitt Ronald F Albrecht David J Miletich 《Prostaglandins & other lipid mediators》1981,21(6):899-904
Prostacyclin (PGI2), prostaglandin E2 (PGE2) and prostaglandin F2∝ (PGF2∝) were tested here in unanesthetized male Sprague-Dawley rats for their effects on the cardiovascular system as mediated by the Central nervous system. Cannulae were chronically implanted into the third cerebral ventricle, femoral arteries and femoral veins of rats. Both PGE2 and PGF2∝ induced increased arterial blood pressure and tachycardia by an action on the central nervous system. The changes seen with PGE2 were larger than those observed with PGF2∝. Only transient depressor effects were seen with PGI2 and these changes appeared to be due to the leakage of the substance into the peripheral vascular system. 相似文献
13.
Cheryl M. Heesch Guillermo Valenzuela Barrie J. Hodgson 《Prostaglandins & other lipid mediators》1977,14(2):279-282
The effects of PGD2, PGF2α and PGE1 were studied on the circular muscle of post-ovulatory rabbit oviducts . PGE1 inhibited spontaneous contractile activity. Lower concentrations of PGD2 and PGF2α were stimulatory and higher concentrations were inhibitory. Since PGD2 may be produced in the oviduct, any hypothesis concerning the role of prostaglandins in the control of oviductal motility and ovum transport should include PGD2 as well as PGFs and PGEs. 相似文献
14.
Triheptafluorobutyrate methyl ester (THFB-Met) derivatives are easily prepared from prostaglandins F1α and F2α by successive methylation and heptafluorobutyrylation. The derivatives are reasonably stable during storage, are volatile, and can be detected in the picogram range by electron-capture gas chromatography. Both derivatives exhibit peak broadening or multiple peak formation during gas chromatography at 190°–210°C. Decomposition is independent of the nature of the stationary phase and can be increased by prior heating. Studies with other derivatives suggest that thermal decomposition of the THFB-Met derivatives occuring during gas chromatography involves loss of a heptafluorobutyrate group from the allylic position 15 of the prostaglandins. 相似文献
15.
Lauren M. Cagen Zahir Qureshi Hiroko Nishimura 《Biochemical and biophysical research communications》1983,110(1):250-255
Saline washed red blood cells of the toadfish convert [1-14C] arachidonic acid to products that cochromatograph with prostaglandin E2 and prostaglandin F2α. This synthesis is inhibited by indomethacin (10 μg/ml). Conversion of arachidonic acid to prostaglandin E2 was confirmed by mass spectrometry. When saline washed toadfish red blood cells were incubated with a mixture of [1-14C]-arachidonic acid and [5,6,8,9,11,12,14,15,-3H]-arachidonic acid, comparison of the isotope ratios of the radioactive products indicated that prostaglandin F2α was produced by reduction of prostaglandin E2. The capacity of toadfish red blood cells to reduce prostaglandin E2 to prostaglandin F2α was confirmed by incubation of the cells with [1-14C] prostaglandin E2. 相似文献
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17.
O. Ylikorkala P. Jouppila P. Ylöstalo P.A. Järvinen 《Prostaglandins & other lipid mediators》1974,7(1):57-70
Prostaglandin F2α administered as single intrauterine injection was used for termination of very early pregnancy in 34 out-patients. Twelve patients were induced with 1.0 mg, 18 patients with 2.0 mg and 4 patients with 4.0 mg of PGF2α. After 2 weeks, abortion was complete in 58% induced with 1.0 mg, in 78% induced with 2.0 mg, and in all 4 patients induced with 4.0 mg. After 3 weeks, abortion was complete in 83% induced with 1.0 mg and in 100% induced with 2.0 mg. There was one failure, which occurred in the group treated by using 1.0 mg PGF2α. Immediate side-effects were kept at an acceptable level with a very mild premedication. No serious complications occurred but curettage was performed on 2 patients because of bleeding. Spontaneous menstruation started in the 1.0 mg group within an average of 33 days (range 23–60), in the 2.0 mg group within an average of 36 days (range 25–61). The use of 2.0 mg PGF2α for the routine termination of very early pregnancy is recommended. 相似文献
18.
W.E. Brenner C.H. Hendricks J. Dingfelder L. Staurovsky 《Prostaglandins & other lipid mediators》1973,3(6):879-894
From interpretation of 24-hour dose-response curves, it is improbable that mid-trimester abortion rates greater than about 80% can be accomplished with any one dose schedule of Prostaglandin F2α (PGF2α). To determine whether augmentation of intra-amniotic PGF2α with laminaria would improve the abortion rate, the results of a group of 22 gravidas treated with intra-amniotic PGF2α were compared to those of a group of 21 subjects treated with laminaria and an identical dose schedule of PGF2α. Patients with laminaria not only had a shorter mean abortion time (14.6 hours), but 95% aborted within 24 hours and all patients aborted within 24.5 hours of the initial PGF2α injection. Patients without laminaria had a longer mean abortion time (18.9 hours); only 68% aborted within 24 hours and one failed to abort within the 48-hour trial period. No significant differences in the frequency or severity of complications between the two groups were observed. Uterine contractility over the initial 6 hours of the induction was similar in the two groups. Therefore, augmenting the intra-amniotic PGF2α method with laminaria appears practicable. 相似文献
19.
Kumiko Kondo Yu Takeyama Ei-ichiro Sunamura Yuka Madoka Yuki Fukaya Atsuko Isu Toru Hisabori 《BBA》2018,1859(5):319-325
F1 is a soluble part of FoF1-ATP synthase and performs a catalytic process of ATP hydrolysis and synthesis. The γ subunit, which is the rotary shaft of F1 motor, is composed of N-terminal and C-terminal helices domains, and a protruding Rossman-fold domain located between the two major helices parts. The N-terminal and C-terminal helices domains of γ assemble into an antiparallel coiled-coil structure, and are almost embedded into the stator ring composed of α3β3 hexamer of the F1 molecule. Cyanobacterial and chloroplast γ subunits harbor an inserted sequence of 30 or 39 amino acids length within the Rossman-fold domain in comparison with bacterial or mitochondrial γ. To understand the structure–function relationship of the γ subunit, we prepared a mutant F1-ATP synthase of a thermophilic cyanobacterium, Thermosynechococcus elongatus BP-1, in which the γ subunit is split into N-terminal α-helix along with the inserted sequence and the remaining C-terminal part. The obtained mutant showed higher ATP-hydrolysis activities than those containing the wild-type γ. Contrary to our expectation, the complexes containing the split γ subunits were mostly devoid of the C-terminal helix. We further investigated the effect of post-assembly cleavage of the γ subunit. We demonstrate that insertion of the nick between two helices of the γ subunit imparts resistance to ADP inhibition, and the C-terminal α-helix is dispensable for ATP-hydrolysis activity and plays a crucial role in the assembly of F1-ATP synthase. 相似文献