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1.
The effects of lanthanum(La) on contractions induced by prostaglandin F2α(PGF2α) or isotonic K+ were investigated in the isolated stomach muscle of guinea-pig.Low concentrations of La(0.1–1 μM) inhibited the contraction to PGF2α 1 μM in a dose-dependent manner, without affecting the tonic contraction to isotonic K+.0.1 and 1 μM La shifted the dose-response curve for PGF2α(0.001 – 1 μM) to the right and reduced the maximum response.The IC50 of La against PGF2α and K+ were 0.6 μM and 30 μM, respectively.These results support the suggestion that PGF2α -induced contraction in the stomach muscle depends mainly on the intracellular release of sequestered Ca, which would be depleted or immobilized by La. 相似文献
2.
J. A. Hemmingson R. Falshaw R. H. Furneaux K. Thompson 《Journal of applied phycology》2006,18(2):185-193
The galactofucan sulfate extract (GFS) obtained from the brown seaweed Undaria
pinnatifida by extraction with dilute acid is a potent inhibitor of the herpes viruses HSV-1, HSV-2 and HCMV, with IC50 values determined in vitro of 1.1, 0.2 and 0.5 μgmL−1, respectively. Fractionation of GFS by anion exchange chromatography gave three fractions which differed in their uronic acid and sulfate contents and in their antiviral activity, as well as in having somewhat reduced molecular weights compared to GFS. The low uronic acid/high sulfate fraction (F2M), obtained in 63% yield, had similar molar proportions of galactopyranosyl and fucopyranosyl residues, little associated protein and was equipotent with GFS (IC50 values of 1.1, 0.1 and 0.5 μgmL−1, respectively). The high uronic acid/low sulfate fraction (F1M), obtained in 18% yield, had a much lower proportion of galactopyranosyl residues and was less active (IC50 values of 4.6, 1.0 and 4.0 μgmL−1, respectively). The minor low uronic acid/high sulfate fraction (F4M) had a significant amount of associated protein and was also less active (IC50 = 3.1, 1.0 and 2.0 μgmL−1, respectively). The structure of the major fraction (F2M) was shown to be complex by glycosyl linkage analysis before and after solvolytic desulfation, with many component sugar residues being identified, although 3-linked fucopyranosyl 2,4-disulfate residues were a prominent feature. 相似文献
3.
We investigated the effect of isoprostanes (IsoPs) on potassium (K+)-depolarization-evoked release of [3H]dopamine from isolated bovine retinae. Isolated retinae were preloaded with [3H]dopamine and then prepared for studies of [3H]dopamine release using the superfusion method. 8-iso(15R)PGF2α, 8-isoPGE2, 8-isoPGE1 and 8-isoPGF2α attenuated [3H]dopamine release from isolated bovine retinae. At a concentration of 1 μM, the rank order of activity displayed by IsoP
agonists was: 8-iso(15R)PGF2α > 8-isoPGE2 > 8-isoPGE1 > 8-isoPGF2α. Inhibition of cyclooxygenase (COX) with flurbiprofen reversed the effects caused by 8-isoPGE2 (10 nM and 10 μM), 8-iso(15R)PGF2α (1 μM) and 8-isoPGE1 (1 μM). Although the EP1/EP2 antagonist, AH 6809 (10 μM) had no significant effect on K+-induced [3H]dopamine release, it blocked the inhibitory effect of both 8-isoPGE1 (10 μM) and 8-isoPGE2 (10 μM). In conclusion, IsoPs attenuate K+-induced [3H]dopamine release in isolated bovine retinae, presumably via an indirect action on COX pathway leading to the production
of prostanoids, which in turn, activates EP receptors. 相似文献
4.
In rat striatal slices labelled with [3H]-adenine and in the presence of 1 mM 3-isobutyl-1-methylxantine (IBMX), cyclic [3H]-AMP ([3H]-cAMP) accumulation induced by the dopamine D1 receptor agonist SKF-81297 (1 μM; 177±13% of basal) was inhibited by the general muscarinic agonist carbachol (maximum inhibition 72±3%, IC50 0.30±0.06 μM). The muscarinic toxin 7 (MT-7), a selective antagonist at muscarinic M1 receptors, reduced the effect of SKF-81297 by 40±7% (IC50 251±57 pM) and enhanced the inhibitory action of a submaximal (1 μM) concentration of carbachol (69±4% vs. 40±7% inhibition, IC50 386±105 pM). The toxin MT-1, agonist at M1 receptors, stimulated [3H]-cAMP accumulation in a modest but significant manner (137±11% of basal at 400 nM), an action additive to that of D1 receptor activation and blocked by MT-7 (10 nM). The effects of MT-7 on D1 receptor-induced [3H]-cAMP accumulation and the carbachol inhibition were mimicked by the PKC inhibitors Ro-318220 (200 nM) and Gö-6976 (200 nM). Taken together our results indicate that in addition to the inhibitory role of M4 receptors, in rat striatum acetylcholine stimulates cAMP formation through the activation of M1 receptors and PKC stimulation. 相似文献
5.
Elevation of the external potassium concentration induced a two-phase inward current in freshly isolated pyramidal hippocampal
neurons. This current was voltage-dependent and demonstrated strong inward rectification. The current consisted of a leakage
current and a time-dependent current (τ=40–50 msec at 21°C); the latter was designated asI
ΔK. As was shown earlier, K+ is a major charge carrier in the development of slow potassium-activated current. The pharmacological properties ofI
ΔK were studied using a patch-clamp technique.I
ΔK was completely blocked by external 10 mM TEA or 5 mM Ba2+ (IC50=480±90mM) and exhibited low sensitivity to extracellular Cs+ (2 mM). This current was not affected by 1 mM 4-aminopyridine and was insensitive to a muscarinic agonist, carbachol (50
μM), and to 1 mM extracellular Cd2+. Elevation of external Ca2+ from 2.5 mM to 10 mM did not changeI
ΔK. Our data indicate that the pharmacological properties ofI
ΔK differ from those of other voltage-gated potassium currents, but more specific blockers must be used to make this evidence
conclusive. 相似文献
6.
The action of 7-oxa-13-prostynoïc acid on spontaneous contractions and on PGF2α and angiotensin II elicited contractions has been studied on rat uteri excised during pro and metaoestrus At the concentration of 5 × 10−6M, the compound does not alter the spontaneous contractions of proestrus uteri and suppresses the phasic component of PGF2α-elicited contractions. At the concentration of 5 × 10−5M, 7-oxa-13-prostynoïc acid inhibits spontaneous contractions and inhibits PGF2α-elicited contractions. In metaoestrus uteri, the inhibitory effect is not competitive. 7-oxa-13-prostynoïc acid is also able to inhibit non competitively the contractor effect of angiotensin II in proestrus uteri. This result, together with those of previous investigations performed using other prostaglandin inhibitors, suggest that the contractor effect of angiotensin II on the uterus is partially mediated by endogenous prostaglandins. 相似文献
7.
Resveratrol (RES), a component of red wine, possesses anti-inflammatory properties. The studies described in the present work
were aimed at evaluating the potential for RES and related stilbene analogs (piceatannol, PIC; pterostilbene, TPS; trans-stilbene, TS; and trans-stilbene oxide, TSO) to exhibit toxicity towards RAW 264.7 mouse macrophages. The effect of TS, TSO, RES and TPS on RAW 264.7
macrophage viability was determined by two standard methods: (a) the MTT assay and (b) the trypan blue dye exclusion test.
Whereas macrophages were more sensitive to PIC (LC50 trypan ∼ 1.3 μM) and to TPS (LC50 trypan ∼ 4.0 μM and LC50 MTT ∼ 8.3 μM) than to RES (LC50 trypan ∼ 8.9 μM and LC50 MTT ∼ 29.0 μM), they were relatively resistant to TSO (LC50 trypan ∼ 61.0 μM and LC50 MTT > 100 μM) and to TS (LC50 trypan ≥ 5.0 μM and LC50 MTT ≥ 5.0 μM). The ability of selected stilbenes (RES, TPS and PIC) to exhibit growth inhibitory effects was also examined. Although
RES and TPS were observed to inhibit cell proliferation in macrophages (IC50 ≤ 25 μM), these cells were resistant to growth inhibition by PIC (IC50 ≥ 50 μM). The data obtained in the present analysis demonstrate that substituted stilbene compounds such as RES have the
capacity to exhibit cytotoxic and anti-proliferative activities in macrophages. 相似文献
8.
9.
Cd2+, Mn2+, and Al3+ inhibited synaptosomal amine uptake in a concentration-dependent and time-dependent manner. In the absence of Ca2+, the rank order of inhibition of noradrenaline uptake was: Cd2+ (IC50 = 250 μM) > Al3+ (IC50 = 430 μM) > Mn2+ (IC50 = 1.50 mM), the IC50 being the concentration of metal ions that gave rise to 50% inhibition of uptake. In the presence of 1 mM Ca2+, the rank order of inhibition of uptake was: Al3+ (IC50 = 330 μM) > Cd2+ (IC50 = 540 μM) > (IC50 = 1.5 mM). The rank order of inhibition of serotonin uptake without Ca2+ was: Al3+ (IC50 = 370 μM) > Cd2+ (IC50 = 610 μM) > Mn2+ (IC50 = 3.4 mM) and the rank order in the presence of 1 mM Ca2+ was: Al3+ (IC50 = 290 μM) > Cd2+ (IC50 = 1.5 mM) > Mn2+ (IC50 = 4.0 mM). Ca2+, at 1 mM, definitely antagonized the inhibitory actions of Cd2+ on noradrenaline and serotonin uptake. Al3+ stimulated noradrenaline uptake at concentrations around 20–250 μM but inhibited this uptake at concentrations exceeding 300 μM in a dose-related fashion. Ca2+, at 1 mM, enhanced both the stimulatory and inhibitory effects of Al3+. Ca2+ also enhanced the inhibitory actions of Al3+ on seotonin uptake. These results, in conjunction with those we have previously published, suggest that Cd2+, Mn2+, and Al3+ exert differential and selective effects on the structure and function of synaptosomal membranes. 相似文献
10.
Inhibition of human platelet aggregation and membrane lipid peroxidation by food spice, saffron 总被引:1,自引:0,他引:1
The inhibitory activity of saffron extract was studied on human platelets. Platelet aggregation and lipid peroxidation were
evaluated with platelet rich plasma (PRP) and platelet membranes respectively obtained from blood of healthy human volunteers.
Human platelets were subjected to stimulation with a variety of agonists like ADP (61 μM), epinephrine (76 μM), collagen (11
μg/ml), calcium ionophore A 23187 (6 μM) and ristocetin (1.25 μg/ml) in the presence and absence of saffron extract with IC50 being 0.66, 0.35, 0.86 and 0.59 mg respectively and no inhibition with ristocetin. The inhibitory effect was dose dependent
with concentrations varying between 0.16 to 0.80 mg and time dependent at IC50. A significant decrease was observed in malondialdehyde (MDA) formed, one of the end products of arachidonic acid metabolism
and of serotonin released from dense granules of platelets at respective IC50. Lipid peroxidation in platelet membranes induced by iron-ascorbic acid system was inhibited by saffron extract significantly
with IC50 of 0.33 mg. Hence, it may be said that aqueous extract of saffron may have component(s), which protect platelets from aggregation
and lipid peroxidation. (Mol Cell Biochem 278: 59–63, 2005) 相似文献
11.
V. L. Zamoyski E. A. Vikhareva V. V. Grigoriev S. O. Bachurin 《Doklady. Biochemistry and biophysics》2016,470(1):332-334
Using patch-clamp method (whole cell configuration), it was shown that tetraethylammonium (TEA) and 4-aminopyridine (4-AP) block calcium-dependent chloride currents in the membrane of freshly isolated cerebellar Purkinje cells of rats (12–15 days). In the concentration range studied (50 μM–10 mM TEA and 100 μM–1 mM 4-AP), both compounds blocked the chloride current at IC50 130 μM for TEA and 110 μM for 4-AP. TEA blockade was reversible after washing. The effect of 4-AP at concentrations greater than 100 μM was irreversible: both outward and inward chloride currents were blocked even after the removal of 4-AP from the incubation medium. 相似文献
12.
Nicotinic acetylcholine receptors (nAChR) are diverse members of the ligand-gated ion channel superfamily of neurotransmitter
receptors and play critical roles in chemical signaling throughout the nervous system. Reports of effects of substance P (SP)
on nAChR function prompted us to investigate interactions between several tachykinins and human nAChR subtypes using clonal
cell lines as simple experimental models. Acute exposure to SP inhibits carbamylcholine- or nicotinestimulated function measured
using86Rb+ efflux assays of human ganglionic (α3β4) nAChR expressed in SH-SY5Y neuroblastoma cells (IC50∼2.3 μM) or of human muscle-type (α1β1γδ) nAChR expressed in TE671/RD clonal cells (IC50∼21 μM). SP also acutely blocks function of rat ganglionic nAChR expressed in PC12 pheochromocytoma cells (IC50∼2.1 μM). Neurokinin A and eledoisin inhibit function (extrapolated IC50 values between 60 and 160 μM) of human muscle-type or ganglionic nAChR, but neurokinin B does not, and neither human nAChR
is as sensitive as PC12 cell α3β4-nAChR to eledoisin or neurokinin A inhibition. At concentrations that produce blockade of
nAChR function, SP fails to affect binding of [3H]acetylcholine to human muscle-type or ganglionic nAChR. SP-mediated blockade of rat or human ganglionic nAChR function is
insurmountable by increasing agonist concentrations. Collectively, these results indicate that tachykinins act noncompetitively
to inhibit human nAChR function with potencies that vary across tachykinins and nAChR subtypes. They also indicate that tachykinin
actions at nAChR could further contribute to complex cross-talk between nicotinic cholinergic and tachykinin signals in regulation
of nervous system activity. 相似文献
13.
Ging Kuo Wang Joanna Calderon Shiow-Jiin Jaw Sho-Ya Wang 《The Journal of membrane biology》2009,229(1):1-9
Articaine is widely used as a local anesthetic (LA) in dentistry, but little is known regarding its blocking actions on Na+ channels. We therefore examined the state-dependent block of articaine first in rat skeletal muscle rNav1.4 Na+ channels expressed in Hek293t cells. Articaine exhibited a weak block of resting rNav1.4 Na+ channels at −140 mV with a 50% inhibitory concentration (IC50) of 378 ± 26 μM (n = 5). The affinity was higher for inactivated Na+ channels measured at −70 mV with an IC50 value of 40.6 ± 2.7 μM (n = 5). The open-channel block by articaine was measured using inactivation-deficient rNav1.4 Na+ channels with an IC50 value of 15.8 ± 1.5 μM (n = 5). Receptor mapping demonstrated that articaine interacted strongly with a D4S6 phenylalanine residue, which is known
to form a part of the LA receptor. Thus the block of rNav1.4 Na+ channels by articaine is via the conserved LA receptor in a highly state-dependent manner, with a ranking order of open (23.9×) > inactivated
(9.3×) > resting (1×) state. Finally, the open-channel block by articaine was likewise measured in inactivation-deficient
hNav1.7 and rNav1.8 Na+ channels, with IC50 values of 8.8 ± 0.1 and 22.0 ± 0.5 μM, respectively (n = 5), indicating that the high-affinity open-channel block by articaine is indeed preserved in neuronal Na+ channel isoforms. 相似文献
14.
Samia Oueslati Najoua Karray-Bouraoui Houneïda Attia Mokded Rabhi Riadh Ksouri Mokhtar Lachaal 《Acta Physiologiae Plantarum》2010,32(2):289-296
Mentha pulegium L. is a medicinal and aromatic plant belonging to the Labiatae family present in the humid to the arid bioclimatic regions
of Tunisia. We studied the effect of different salt concentrations on plant growth, mineral composition and antioxidant responses.
Physiological and biochemical parameters were assessed in the plant organs after 2 weeks of salt treatment with 25, 50, 75
and 100 mM NaCl. Results showed that, growth was reduced even by 25 mM, and salt effect was more pronounced in shoots (leaves
and stems) than in roots. This growth decrease was accompanied by a restriction in tissue hydration and K+ uptake, as well as an increase in Na+ levels in all organs. Considering the response of antioxidant enzymes to salt, leaves and roots reacted differently to saline
conditions. Leaf and root guaiacol peroxidase activity showed an increase by different concentration of NaCl, but superoxide
dismutase activity in the same organs showed a slight modification in NaCl-treated leaves and roots. Moreover, polyphenol
contents and antioxidant activity were analysed in M. pulegium leaves and roots under salt constraint. The analysis showed an increase of total polyphenol content (2.41–8.17 mg gallic
acid equivalent g−1 dry weight) in leaves. However, methanol extract of leaves at 100 mM NaCl displayed the highest DPPH· scavenging ability
with the lowest IC50 value (0.27 μg ml−1) in comparison with control which exhibited IC50 equal to 0.79 μg ml−1. 相似文献
15.
Bacteroids formed by Mesorhizobium ciceri CC 1192 in symbiosis with chickpea plants (Cicer arietinum L.) contained a single form of citrate synthase [citrate oxaloacetate-lyase (CoA-acetylating) enzyme; EC 4.1.3.7], which
had the same electrophoretic mobility as the enzyme from the free-living cells. The citrate synthase from CC 1192 bacteroids
had a native molecular mass of 228 ± 32 kDa and was activated by KCl, which also enhanced stability. Double reciprocal plots
of initial velocity against acetyl-CoA concentration were linear, whereas the corresponding plots with oxaloacetate were nonlinear.
The K
m value for acetyl-CoA was 174 μM in the absence of added KCl, and 88 μM when the concentration of KCl in reaction mixtures
was 100 mM. The concentrations of oxaloacetate for 50% of maximal activity were 27 μM without added KCl and 14 μM in the presence
of 100 mM KCl. Activity of citrate synthase was inhibited 50% by 80 μM NADH and more than 90% by 200 μM NADH. Inhibition by
NADH was linear competitive with respect to acetyl-CoA (K
is = 23.1 ± 3 μM) and linear noncompetitive with respect to oxaloacetate (K
is = 56 ± 3.8 μM and K
ii = 115 ± 15.4 μM). NADH inhibition was relieved by NAD+ and by micromolar concentrations of 5′-AMP. In the presence of 50 or 100 mM KCl, inhibition by NADH was apparent only when
the proportion of NADH in the nicotinamide adenine dinucleotide pool was greater than 0.6. In the microaerobic environment
of bacteroids, NADH may be at concentrations that are inhibitory for citrate synthase. However, this inhibition is likely
to be relieved by NAD+ and 5′-AMP, allowing carbon to enter the tricarboxylic acid cycle.
Received: 14 July 1999 / Accepted: 20 September 1999 相似文献
16.
The metabolites produced by Stigmatella WXNXJ-B inhibited the growth of tumor cells. The aims of this research were to evaluate the inhibition potency to different
tumor cell lines and to study the effects of ammonium, phosphate and iron salts on bacterial growth and production of bioactive
metabolites in Stigmatella WXNXJ-B fermentation. The results showed that the chloroform extract (CE-ME) showed the strongest growth inhibition bioactivity
on mouse melanoma cell line (B16), murine colon carcinoma cell line (CT-26), human liver carcinoma cell line (HepG2) and human
breast cancer cell line (MDA-MB231) in vitro and the IC50 values were 9.94, 7.33, 11.34 and 11.66 μg ml−1 respectively. The IC50 value was above 700 μg ml−1 on normal mouse spleen cells. Morphology happened changes in B16 cells treated with CE-ME. The anti-tumor metabolites were
mainly produced during the stationary phase of the bacterial growth. Cell growth was stimulated at the phosphate concentration
below 5 mM, but it was inhibited partly with 10 mM phosphate. The production of bioactive substances was inhibited by the
phosphate. Ammonium increased the cell growth by 250% at 5 mM addition. The inhibition rate to B16 cells was increased to
89% at the concentration of 40 mM ammonium. The bacteria showed the best growth with 4 mM iron. Iron had little effect on
the production at 2 mM, but bigger inhibition effect at higher iron concentration. 相似文献
17.
T. Laudanski M.D. Ph.D. A. Kostrzewska Ph.D. kerlund 《Prostaglandins & other lipid mediators》1986,32(1)
The effect of cupric ions on the human uterus and the involvement of prostaglandins (PGs) in mediating this effect was studied by recording of isometric contractions of isolated myometrial strips and pieces of uterine arteries, and by intrauterine pressure recordings in women before the onset of menstruation.
, CuCl2 in concentrations of 10−4 M and higher caused a significant inhibition of myometrial contractile activity, but no effect on the artery preparations was seen. Furthermore, the contractile response of myometrial strips to PGF2α and PGE2 (10 ng/ml) decreased in the presence of CuCl2 in concentrations of 5 and 50 μmol.
, instillations of 0.3, 1.0 and 2.0 mM of CuCl2 in 0.7 ml of saline solution into the uterine cavity caused a dose-dependent stimulation of uterine activity, but after pretreatment with naproxen, 500 mg orally, the effect of these substances was abolished. After naproxen treatment, but during infusion of PGF2α (5 μg/min), the response to the CuCl2 solutions was partially restored. It is suggested that cupric ions, at high concentrations, have an inhibiting effect on myometrial activity. The stimulatory effect of low doses of CuCl2 seen after installation into the uterine cavity is largely exerted via initiation of synthesis and release of endometrial PGs. 相似文献
18.
Shao YX Zhao P Li Z Liu M Liu P Huang M Luo HB 《European biophysics journal : EBJ》2012,41(3):297-306
In our previous kinetics studies the natural products oroxylin and wogonin were shown to have strong biological affinity for,
and inhibitory effects against, human cytochrome P450 1A2, with IC50 values of 579 and 248 nM, respectively; this might lead to the occurrence of drug–drug interactions when co-administered clinically. However, their
inhibitory mechanisms against 1A2 remain elusive. In this study, molecular docking and molecular dynamics simulations were
performed to better understand the molecular basis of their inhibitory mechanisms towards 1A2. Structural analysis revealed
that oroxylin has a different binding pattern from wogonin and another very strongly binding inhibitor α-naphthoflavone (ANF,
IC50 = 49 nM). The O7 atom of oroxylin forms hydrogen bonds with the OD1/OD2 atoms of Asp313, which is not observed in the 1A2–wogonin complex.
Because of energetically unfavorable repulsions with the methoxy group at the 6 position of the oroxylin ring, significant
conformational changes were observed for the sidechain of Thr118 in the MD simulated model. As a result, the larger and much
more open binding-site architecture of the 1A2–oroxylin complex may account for its weaker inhibitory effect relative to the
1A2–ANF complex. Energy analysis indicated that oroxylin has a less negative predicted binding free energy of −19.8 kcal/mol
than wogonin (−21.1 kcal/mol), which is consistent with our experimental assays. Additionally, our energy results suggest
that van der Waals/hydrophobic and hydrogen-bonding interactions are important in the inhibitory mechanisms of oroxylin whereas
the former is the underlying force responsible for strong inhibition by ANF and wogonin. 相似文献
19.
The GABAA Receptor Complex as a Target for Fluoxetine Action 总被引:3,自引:0,他引:3
Tunnicliff G. Schindler N. L. Crites G. J. Goldenberg R. Yochum A. Malatynska E. 《Neurochemical research》1999,24(10):1271-1276
The clinically important antidepressant fluoxetine is established as a selective serotonin reuptake inhibitor. This study demonstrates that fluoxetine also interacts with the GABAA receptor complex. At concentrations above 10 M fluoxetine inhibited the binding of both [3H]GABA (IC50 = 2 mM) and [3H]flunitrazepam (IC50 = 132 M ) to the GABAA receptor complex in brain cortical membranes. Low fluoxetine concentrations (1 nM) enhanced GABA-stimulated Cl– uptake by a rat cerebral cortical vesicular preparation. At higher concentrations (100 M and 1 mM), however, fluoxetine inhibited GABA-stimulated Cl– uptake, an effect related to a reduction in Emax. These observations might assist in an explanation of the basis of the antidepressant action of fluoxetine. 相似文献
20.
《Prostaglandins, Leukotrienes and Medicine》1984,13(3):259-269
The basal outputs of prostaglandin (PG) F2α and PGE2 from the Day 15 guinea-pig uterus superfused in vitro were unaffected by omitting Ca2+ from the Krebs' solution. In contrast, this omission of Ca2+ reduced the basal output of 6-oxo-PGF1α (which reflects PGI2 production) from the uterus by an average of 50%. Spontaneous and A23187-stimulated contractions of, and the stimulation by A23187 of PGF2α, PGE2 and 6-oxoPGF1α outputs from the Day 15 guinea-pig uterus were all abolished by superfusing the tissue with Krebs' solution lacking Ca2+. It is concluded that the basal output of 6-oxo-PGF1α, the occurrence of spontaneous contractions, and the effects of A23187 on PG output and contractility of the Day 15 guinea-pig uterus are dependent on extracellular Ca2+. However, the increase in PGF2α output from the guinea-pig uterus on Day 15 compared to days much earlier in the cycle is apparently not dependent upon extracellular Cat+. The implications of these findings regarding the biochemical mechanisms involved in the increased synthesis of PGF2α (the uterine luteolytic hormone) by the guinea-pig endometrium during the last one-third of the cycle are discussed. 相似文献