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PubMed1997

Assisted reproduction technology in Queen Mary Hospital: ten years' experience.

PURPOSE: To review the experience of an assisted reproduction program. DATA SOURCES: Department of Obstetrics and Gynaecology, University of Hong Kong. STUDY SELECTION: Assisted reproduction in a tertiary referral centre. DATA EXTRACTION: Results of assisted reproduction from 1986-1996. RESULTS: In the past ten years, 1561 treatment cycles of in vitro fertilization and embryo transfer (IVF), 257 of gamete intrafallopian transfer (GIFT) and 217 of pronuclear stage tubal transfer (PROST) were initiated. The clinical pregnancy rates per cycle started were 10.8% for IVF, 16.3% for GIFT and 15.7% for PROST. As a result of improvement in ovarian stimulation and embryo culture, the success rate of the program increased in recent years. The pregnancy rate of IVF per embryo transfer was 20.2% in 1995. Embryo cryopreservation program was started in 1992. Since then, 664 cycles of replacement of frozen-thawed embryos were completed with a pregnancy rate of 14.6% per cycle. One hundred and forty-three cycles of assisted fertilization using various techniques, namely partial zona dissection, subzonal sperm injection and intracytoplasmic sperm injection, were performed. The success rate was the highest for the latter technique with a pregnancy rate of 14% per transfer cycle. A prospective randomized control trial on the use of coculture in assisted reproduction had also been done. Results indicated that coculture of embryos with human oviductal cells improved the implantation rate of the embryos. CONCLUSION: Various technique development have been made to improve the success rate of assisted reproduction as well as the quality of treatment of infertility.

Embryo Transfer↗

PubMed2003

Comparison of two microalgal diets. 2. Influence on odorant composition and organoleptic qualities of raw oysters (Crassostrea gigas).

Oyster farming is of real economic interest in France. Oyster farmers attach more and more importance to improving the growth and the quality of their oysters. Some fatty acids known to be aroma precursors originate from microalgae such as Skeletonema costatum and Tahitian isochrysis clone. These microalgae were used to fatten oysters in order to observe their role in the development of oysters' aroma. This study shows that the profile of fatty acids of oysters is influenced by the contribution of fatty acids from the two microalgae (as reported in the first paper in this series: Pennarun, A.-L.; Prost, C.; Haure, J.; Demaimay, M. Comparison of Two Microalgal Diets. 1. Influence on the Biochemical and Fatty Acid Compositions of Raw Oysters (Crassostrea gigas). J. Agric. Food Chem. 2003, 51, 2006-2010 (in this issue)]. As a consequence, a microalgal diet causes changes in oysters' aroma composition. Aroma concentration depends on the content of fatty acids that are aroma precursors in oysters. Some aromas are characteristic of the diet of S. costatum, such as 6-methyl-5-hepten-2-one (ether odor), and others are characteristic of T. isochrysis, such as 3-nonyne (cucumber, marine odor), 6-(E)-nonen-1-ol (green and fresh odor), and 4-ethylbenzaldehyde (aniseed odor). Moreover, the organoleptic qualities (odor, taste, and texture) of oysters are modified by the diet of microalgae.

Animals↗

PubMed1989

Pregnancies established by gamete intrafallopian transfer and pronuclear-stage transfer in patients with premature ovarian failure using donated oocytes and low-dose oral micronized estradiol and progesterone.

This report describes both gamete intrafallopian transfer (GIFT) and pronuclear-stage transfer (PROST) of donated oocytes to patients with premature ovarian failure (POF), using micronized oral progesterone (P4) and low-dose micronized estradiol (E2) for endometrial preparation and maintenance. Patient A, with POF of 15 years' duration, received four donated oocytes for GIFT and subsequently delivered a normal, term, female infant. Patient B was diagnosed as POF 3 years ago. She received four donated oocytes, which were subsequently fertilized in vitro with husband's sperm. The following day, four pronuclear-stage embryos were transferred to her fallopian tubes. She recently delivered twin, healthy female infants. These procedures, along with exogenous hormonal development of the endometrium, provide a simplified means to establish and maintain pregnancy in POF patients. Both patients were maintained on low-dose micronized E2 prior to their procedure, Patient A on 3 mg E2 per day cyclically and Patient B on 0.5 mg E2 continuously. Micronized oral P4 was used to maintain pregnancy.

Adult↗

PubMed1991

Treatment of severe male-factor infertility with high concentrations of motile sperm by microinsemination in embryo cryopreservation straws.

A microinsemination technique was evaluated for treating our program's most severe cases of male-factor infertility. Oocytes were inseminated with high concentrations of motile sperm (1 to 9 x 10(6)/ml) in 10 to 150 microliters within embryo cryopreservation straws. Fertilization was obtained in 20 of 29 (69%) couples treated by this technique. In the 15 patients in which only embryos generated from the straw technique were transferred, 7 clinical pregnancies resulted (46.7% per transfer). The implantation rate for couples receiving embryos from the straw technique only (12/58; 20.7%) compared favorably to that observed for other cases treated during this same time period with regular insemination techniques (111/766; 14.5%). Clinical pregnancy rates per transfer for IVF-ET, TET, and PROST were 33.0% (1/3), 0% (0/2), and 60.0% (6/10), respectively. The percentage of polyploidic embryos was significantly lower (P less than 0.0001) for male-factor patients treated by the straw technique with high sperm concentrations than for non-male-factor patients treated during this same time period with standard sperm concentrations. Normal births have resulted from straw inseminations with 3.4 x 10(6) and ongoing pregnancies with 5.0 x 10(6) motile sperm/ml. The results of this study suggest that some cases of male-factor infertility can be successfully treated by insemination with high concentrations of motile sperm in embryo cryopreservation straws. A technique of centrifuging sperm in straws was also developed to concentrate the entire fraction of washed sperm into 10 microliters. Further development of this technique may allow treatment of more severe cases of oligo/asthenospermia by microinsemination with high concentrations of motile sperm than is presently possible with standard washing techniques.

Adult↗

PubMed1989

Pituitary down-regulation using leuprolide for the intensive ovulation management of poor prognosis patients having in vitro fertilization (IVF)-related treatments.

A review of 118 treatment cycles in 115 women under prolonged GnRH analogue (GnRHa; leuprolide) treatment is presented. Patients were selected for treatment primarily on the grounds of poor previous response to stimulation (n = 40), advanced age (greater than 35 years; n = 29), previous premature luteinizing hormone (LH) surge (n = 30), polycystic ovarian disease (PCO; n = 12), and elevated androgens without evidence of PCO (n = 5). An overall pregnancy rate of 28.8% per treatment cycle was attained, compared with a pregnancy rate of 6.2% (6/97, of which none went to term) in the previous completed treatment cycle for the same patients. Ovarian response, as measured by oocytes recovered and maximum estradiol levels observed, was significantly improved in all groups and this was associated with a prolonged follicular phase, significantly more human menopausal gonadotropin (hMG) stimulation and a relatively high incidence of ovarian hyperstimulation, particularly in pregnant patients. Of specific techniques in the GnRHa cycle, GIFT produced a pregnancy rate per treatment of 50% (10/20); IVF-ET, 22% (8/36); PROST, 28% (13/46); and TEST, 19% (3/16). No cycles were abandoned, compared with a cancellation rate of 24% in previous cycles without GnRHa. Patients with PCO performed particularly well on GnRHa management, with a pregnancy rate per treatment of 58% (7/12). Pregnancy rates per treatment for the other groups were as follows: elevated age, 27% (9/33), high androgens, 40% (2/5); premature LH surges, 32% (9/28); and poor responders, 17.5% (7/40).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1984

Studies on the luteolytic activity of MDL-646, a new gastroprotective PGE1 analogue, in the hamster.

MDL-646, 11,15-dihydroxy-16-methyl-16-methoxy-9-oxo- prost -13-en-1-oic acid methyl ester, is one of the most active members of a new class of PGE1 analogues with potent gastric cytoprotective and antisecretory activity. The potential luteolytic activities of MDL-646 and its corresponding PGE2 derivative, L 14224 were assessed from their ability to terminate pregnancy and to reduce plasma progesterone levels in the hamster. PGE1 and PGE2 were used as reference compounds. The biological and biochemical data clearly demonstrate that these 16-methyl-16-methoxy PGE derivatives, given s.c. or p.o. either once or for 3 days, have no luteolytic effects up to a daily dose of 2-2.5 mg/kg, and are therefore at most 1/2 to 1/4 as luteolytic as the parent natural PGEs. The dissociation between gastroprotective and luteolytic activity was interpreted to indicate that these new PGE derivatives have a specific action.

Abortion, Spontaneous↗

PubMed1991

Electrolyte effects on bilayer tubule formation by a diacetylenic phospholipid.

A general effect by dissolved electrolytes to destabilize the curvature of bilayer tubules prepared from the diacetylenic phospholipid, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine is not found. This observation discounts the role of an electrostatic interaction between polarization charges on the edges of a ferroelectric bilayer as a means by which the cylindrical curvature may be stabilized in these structures (de Gennes, P. G. 1987. C. R. Acad. Sci. Paris. 304:259-263). The solution-mediated ionic interactions of electrolytes with this phospholipid appear not to influence significantly the relative stability of the crystalline state of the tubule, but at high levels of a few salts, may affect the nucleation and growth of the crystalline bilayer. Curvature of the bilayer in these tubular structures apparently derives from an interaction that is not very sensitive to the presence of electrolytes. Cylindrical curvature may alternatively arise from a bending force within the bilayer that is intrinsic to the anisotropic packing of the lipid molecules (Helfrich, W., and J. Prost. 1988. Phys. Rev. A38:3065-3068; Chappell, J. S., and P. Yager. 1991. Chem. Phys. Lipids. In press), and may therefore be largely determined by the packing interactions within the hydrophobic region of the tubular bilayer.

Calorimetry↗

PubMed1992

After superovulation-intrauterine insemination fails: the prognosis for treatment by gamete intrafallopian transfer/pronuclear stage transfer.

OBJECTIVE: To determine the prognosis for gamete intrafallopian transfer (GIFT)/pronuclear stage transfer (PROST) treatment after prior superovulation-intrauterine insemination (IUI). DESIGN: Matched, retrospective. SETTING: Outpatient university endocrine-infertility program. PATIENTS, PARTICIPANTS: One hundred forty-four women matched for infertility factors and age were studied according to the following three treatment groups: superovulation-IUI only, GIFT/PROST only, or GIFT/PROST after superovulation-IUI. MAIN OUTCOME MEASURES: Per cycle and cumulative pregnancy rates (PRs) were compared utilizing life table analysis. RESULTS: Cumulative PRs (0.408) for superovulation-IUI only were lower than initial (0.469) and cumulative (0.802) cycle fecundity of GIFT/PROST (P = 0.002). Per cycle and cumulative PRs did not differ between GIFT/PROST only versus GIFT/PROST after superovulation-IUI. CONCLUSIONS: Gamete intrafallopian transfer/PROST may be cost-effective when compared with superovulation-IUI. The prognosis for GIFT/PROST success is not negatively affected by earlier superovulation-IUI treatment failure.

Adult↗

PubMed2004

Identification of Tyr504 as an alternative tyrosyl radical site in human prostaglandin H synthase-2.

Hydroperoxides induce formation of a tyrosyl radical on Tyr385 in prostaglandin H synthase (PGHS). The Tyr385 radical initiates hydrogen abstraction from arachidonic acid, thereby mechanistically connecting the peroxidase and cyclooxygenase activities. In both PGHS isoforms the tyrosyl radical undergoes a time-dependent transition from a wide doublet to a wide singlet species; pretreatment with cyclooxygenase inhibitors results in a third type of signal, a narrow singlet [Tsai, A.-L.; Kulmacz, R. J. (2000) Prost. Lipid Med. 62, 231-254]. These transitions have been interpreted as resulting from Tyr385 ring rotation, but could also be due to radical migration from Tyr385 to another tyrosine residue. PATHWAYS analysis of PGHS crystal structures identified four tyrosine residues with favorable predicted electronic coupling: residues 148, 348, 404, and 504 (ovine PGHS-1 numbering). We expressed recombinant PGHS-2 proteins containing single Tyr --> Phe mutations at the target residues, a quadruple mutant with all four tyrosines mutated, and a quintuple mutant, which also contains a Y385F mutation. All mutants bind heme and display appreciable peroxidase activity, and with the exception of the quintuple mutant, all retain cyclooxygenase activity, indicating that neither of the active sites is significantly perturbed. Reaction of the Y148F, Y348F, and Y404F mutants with EtOOH generates a wide singlet EPR signal similar to that of native PGHS-2. However, reaction of the Y504F and the quadruple mutants with peroxide yields persistent wide doublets, and the quintuple mutant is EPR silent. Nimesulide pretreatment of Y504F and the quadruple mutant results in an abnormally small amount of wide doublet signal, with no narrow singlet being formed. Therefore, the formation of an alternative tyrosine radical on Tyr504 probably accounts for the transition from a wide doublet to a wide singlet in native PGHS-2 and for formation of a narrow singlet in complexes of PGHS-2 with cyclooxygenase inhibitors.

Binding, Competitive↗

PubMed1999

Processing of grammatical gender in a three-gender system: experimental evidence from Russian.

Four experiments investigated the effect of grammatical gender on lexical access in Russian. Adjective-noun pairs were presented auditorily, using a cued-shadowing technique in which subjects must repeat the second word (the target noun), following adjectives that are either concordant or discordant with the noun's gender. Experiment 1 demonstrates gender priming with unambiguous adjectives and phonologically transparent masculine or feminine nouns. Experiment 2 examines priming for transparent nouns against a neutral baseline (possible only for feminines and neuters), revealing that priming is due primarily to inhibition from discordant gender. Experiment 3 demonstrates gender priming with phonologically opaque masculine and feminine nouns. Experiment 4 returns to transparent masculine and feminine nouns with a different kind of baseline, using three versions of a single word root (prost--simple, in the feminine adjectival form prostaja, masculine adjectival form prostoj, and the adverbial form prosto), and shows that gender can also facilitate lexical access, at least for feminine nouns. We conclude that Russian listeners can exploit gender agreement cues "on-line," helping them to predict the identity of an upcoming word.

Adolescent↗

PubMed1999

The isocitrate dehydrogenase kinase/phosphatase from Escherichia coli is highly sensitive to in-vitro oxidative conditions role of cysteine67 and cysteine108 in the formation of a disulfide-bonded homodimer.

Isocitrate dehydrogenase kinase/phosphatase (IDHK/P) is a homodimeric enzyme which controls the oxidative metabolism of Escherichia coli, and exibits a high intrinsic ATPase activity. When subjected to electrophoresis under nonreducing conditions, the purified enzyme migrates partially as a dimer. The proportion of the dimer over the monomer is greatly increased by treatment with cupric 1,10 phenanthrolinate or 5,5'-dithio-bis(2-nitrobenzoic acid), and fully reversed by dithiothreitol, indicating that covalent dimerization is produced by a disulfide bond. To identify the residue(s) involved in this intermolecular disulfide-bond, each of the eight cysteines of the enzyme was individually mutated into a serine. It was found that, under nonreducing conditions, the electrophoretic patterns of all corresponding mutants are identical to that of the wild-type, except for the Cys67-->Ser which migrates exclusively as a monomer and for the Cys108-->Ser which migrates preferentially as a dimer. Furthermore, in contrast to the wild-type enzyme and all the other mutants, the Cys67-->Ser mutant still migrates as a monomer after treatment with cupric 1,10 phenanthrolinate. This result indicates that the intermolecular disulfide bond involves only Cys67 in each IDHK/P wild-type monomer. This was further supported by mass spectrum analysis of the tryptic peptides derived from either the cupric 1,10 phenanthrolinate-treated wild-type enzyme or the native Cys108-->Ser mutant, which show that they both contain a Cys67-Cys67 disulfide bond. Moreover, both the cupric 1,10 phenanthrolinate-treated wild-type enzyme and the native Cys108-->Ser mutant contain another disulfide bond between Cys356 and Cys480. Previous results have shown that this additional Cys356-Cys480 disulfide bond is intramolecular [Oudot, C., Jault, J.-M., Jaquinod, M., Negre, D., Prost, J.-F., Cozzone, A.J. & Cortay, J.-C. (1998) Eur. J. Biochem. 258, 579-585].

Base Sequence↗

PubMed2003

Membrane tube formation from giant vesicles by dynamic association of motor proteins.

The tubular morphology of intracellular membranous compartments is actively maintained through interactions with motor proteins and the cytoskeleton. Moving along cytoskeletal elements, motor proteins exert forces on the membranes to which they are attached, resulting in the formation of membrane tubes and tubular networks. To study the formation of membrane tubes by motor proteins, we developed an in vitro assay consisting of purified kinesin proteins directly linked to the lipids of giant unilamellar vesicles. When the vesicles are brought into contact with a network of immobilized microtubules, membrane tubes and tubular networks are formed. Through systematic variation of the kinesin concentration and membrane composition we study the mechanism involved. We show that a threshold concentration of motor proteins is needed and that a low membrane tension facilitates tube formation. Forces involved in tube formation were measured directly with optical tweezers and are shown to depend only on the tension and bending rigidity of the membrane. The forces were found to be higher than can be generated by individual motor proteins, indicating that multiple motors were working together to pull tubes. We propose a simple mechanism by which individual motor proteins can dynamically associate into clusters that provide the force needed for the formation of tubes, explaining why, in contrast to earlier findings [Roux, A., Cappello, G., Cartaud, J., Prost, J., Goud, B. & Bassereau, P. (2002) Proc. Natl. Acad. Sci. USA 99, 5394-5399], motor proteins do not need to be physically linked to each other to be able to pull tubes.

Cell Membrane↗

PubMed2003

Sequential autophosphorylation steps in the interleukin-1 receptor-associated kinase-1 regulate its availability as an adapter in interleukin-1 signaling.

The interleukin-1 receptor-associated kinase 1 (IRAK-1) is an important adapter in the signaling complex of the Toll/interleukin-1 (IL-1) receptor family. Formation of the signaling IL-1 receptor complex results in the activation and hyperphosphorylation of IRAK-1, which leads to a pronounced shift of its apparent molecular mass in gel electrophoresis. Presently, the individual residues phosphorylated in IRAK-1 and the consequences for IRAK-1 function are unknown. We define sequential phosphorylation steps in IRAK-1, which are, in vitro, autophosphorylation. First, IRAK-1 is phosphorylated at Thr209. By fluorescence energy transfer experiments, we demonstrate that Thr209 phosphorylation results in a conformational change of the kinase domain, permitting further phosphorylations to take place. Substitution of Thr209 by alanine results in a kinase-inactive IRAK-1. Second, Thr387 in the activation loop is phosphorylated, leading to full enzymatic activity. Third, IRAK-1 autophosphorylates several times in the proline-, serine-, and threonine-rich ProST region between the N-terminal death domain and kinase domain. Hyperphosphorylation of this region leads to dissociation of IRAK-1 from the upstream adapters MyD88 and Tollip but leaves its interaction with the downstream adapter TRAF6 unaffected. This identifies IRAK-1 as a novel type of adapter protein, which employs its own kinase activity to introduce negative charges adjacent to the protein interaction domain, which anchors IRAK-1 at the active receptor complex. Thus, IRAK-1 regulates its own availability as an adapter molecule by sequential autophosphorylation.

Adaptor Proteins, Signal Transducing↗

PubMed1992

Improved development of human embryos in vitro by a human oviductal cell co-culture system.

This study was undertaken to determine the effect of co-culture with human oviductal cells on human embryos. Spare embryos from gamete intra-Fallopian transfer (GIFT), pronuclear stage transfer (PROST) and in-vitro fertilization/embryo transfer (IVF/ET) programmes were either cultured in serum-supplemented Earle's balanced salt solution alone, or co-cultured in the same solution with oviductal cells from the pronuclear stage (day 1 post-insemination) or two- to four-cell stage (day 2 post-insemination). The co-cultured embryos appeared to have a higher developmental potential (higher rate of blastocyst formation and lower fragmentation rate), although there was no statistical difference in their rate of development, degree of fragmentation and stages attained, when compared with conventionally cultured embryos. The percentage of hatching blastocysts was significantly higher (P less than 0.05, Fisher's exact test) for embryos co-cultured from day 1 post-insemination (38%) than for embryos which had not been co-cultured (7%). The blastocyst hatching rate for embryos co-cultured from day 2 post-insemination was 15%. It was therefore concluded that co-culture of human embryos with oviductal cells could improve the development of the embryos in vitro. The degree of improvement was more pronounced when the co-culture started at an earlier stage.

Blastocyst↗

PubMed1999

Asymmetry and direction reversal in fluctuation-induced biased Brownian motion.

The biased movement of a Brownian particle in a periodic potential fluctuating between a flat and a kinked ratchet state, as first studied by Chauwin, Ajdari, and Prost, is examined. The purpose is to study the physical origin of the frequency-dependent direction reversal of the biased Brownian motion in this system. We show that the existence of the directional reversal depends not only on the lengths of the projections of the two ratchet arms on the potential axis (the arm-projection asymmetry), but also the overall spatial geometry of the potential in a period. In particular, we show that the direction reversal can be obtained in this kinked ratchet model even when the two arm projections are equal. Since this two-state model is the simplest to generate direction reversal and particles can be separated more efficiently in a fluctuating potential if direction reversal exists, the results obtained in this study should be useful for future application in particle separation.

Journal Article↗

PubMed2000

Statistical mechanics of vacancy and interstitial strings in hexagonal columnar crystals

Columnar crystals contain defects in the form of vacancy-interstitial loops or strings of vacancies and interstitials bounded by column "heads" and "tails." These defect strings are oriented by the columnar lattice and can change size and shape by movement of the ends and by forming kinks along the length. Hence an analysis in terms of directed living polymers [S. A. Safran, Statistical Thermodynamics of Surfaces, Interfaces, and Membranes (Addison-Wesley, Reading, MA, 1994), Sec. 8] is appropriate to study their size and shape distribution, volume fraction, etc. If the entropy of transverse fluctuations overcomes the string line tension in the crystalline phase, a string proliferation transition occurs, leading to a supersolid phase [E. Frey, D. R. Nelson, and D. S. Fisher, Phys. Rev. B 49, 9723 (1994); see also J. Prost, Liq. Cryst. 8, 123 (1990)]. We estimate the wandering entropy and examine the behavior in the transition regime. We also calculate numerically the line tension of various species of vacancies and interstitials in a triangular lattice for power-law potentials as well as for a modified Bessel function interaction between columns such as occurs in the case of flux lines in type-II superconductors or long polyelectrolytes in an ionic solution. We find that the centered interstitial is the lowest-energy defect for a very wide range of interactions; the symmetric vacancy is preferred only for extremely short interaction ranges.

Journal Article↗

PubMed1988

Early pregnancy wastage after gamete manipulation.

The outcome of 1034 pregnancies in women who conceived after referral for infertility management in seven treatment groups is detailed. The mean early pregnancy wastage (before 20 weeks gestation) was 27% and ranged from 18% after AID (artificial insemination by donor semen) to 33% after IVF-ET (in-vitro fertilization and embryo transfer). These differences were not due to maternal age which was similar in all groups (means between 29.7 and 32.7 years). Excluding the AID group, there was a high rate of ectopic pregnancy which was significantly higher after GIFT (gamete intrafallopian transfer) and was only partly related to underlying tubal disease. Blighted ova was the main category of early pregnancy loss and was highest after AIH (artificial insemination by husband's semen). There was a higher rate of biochemical pregnancies after GIFT, PROST (pronuclear stage tubal transfer) and IVF-ET. Our findings confirm a high pregnancy wastage rate in subfertile women and highlight deficiencies in the sperm separation, gamete handling and IVF/embryo culture techniques.

Abortion, Spontaneous↗

PubMed2006

Prostanoid receptors regulate the volume-sensitive efflux of osmolytes from murine fibroblasts via a cyclic AMP-dependent mechanism.

The ability of prostanoid receptors to regulate the volume-dependent efflux of the organic osmolyte taurine from murine fibroblasts (L cells) via a cAMP-dependent mechanism has been examined. Incubation of L cells under hypoosmotic conditions resulted in a time-dependent efflux of taurine, the threshold of release occurring at 250 mOsM. Addition of prostaglandin E(1) (PGE(1)) potently (EC(50) = 2.5 nM) enhanced the volume-dependent efflux of taurine at all time points examined and increased the threshold for osmolyte release to 290 mOsM. Maximal PGE(1) stimulation (250-300% of basal) of taurine release was observed at 250 mOsM. Of the PGE analogs tested, only the EP(2)-selective agonist butaprost (9-oxo-11alpha,16S-dihydroxy-17-cyclobutyl-prost-13E-en-1-oic acid) was able to enhance taurine efflux. Inclusion of 1,9-dideoxyfoskolin, 5-nitro-2-(3-phenylpropylamino) benzoic acid, or 4-[(2-butyl-6,7-dicloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]-butanoic acid blocked the ability of PGE(1) to enhance taurine release, indicating the mediation of a volume-sensitive organic osmolyte and anion channel. The ability of PGE(1) to increase osmolyte release from L cells was mimicked by the addition of agents that inhibit cAMP breakdown, directly activate adenylyl cyclase, or are cell-permeant analogs of cAMP. Taurine release elicited by either PGE(1) or 8-(4-chlorophenylthio)-cAMP was attenuated by >70% in L cells that had been stably transfected with a mutant regulatory subunit of cAMP-dependent protein kinase (PKA). PGE(1) stimulation of taurine efflux was not attenuated by either depletion of intracellular calcium or inhibition of protein kinase C. The results indicate that activation of prostanoid receptors on murine fibroblasts enhances osmolyte release via a cAMP and PKA-dependent mechanism.

Alprostadil↗