下载免费PDF全文 2 5-HT contracted the dog isolated femoral artery and saphenous vein over the concentration-range 1.0 × 10-8 to 5.0 × 10-6 mol/l.
3 In the femoral artery methysergide and cyproheptadine were potent, competitive and specific antagonists of the contractile responses to 5-HT, with pA2 values of 8.52 and 8.55 respectively.
4 In the saphenous vein, methysergide was only a weak antagonist of 5-HT. In addition, it was an agonist over the concentration-range 5.0 × 10-8 to 1.0 × 10-5 mol/l. Cyproheptadine was a weak and unsurmountable antagonist of contractile responses to 5-HT and methysergide.
5 Contractile responses to 5-HT and methysergide in the saphenous vein were not antagonized by morphine (3.0 × 10-5 mol/l), indomethacin (5.0 × 10-5 mol/l), phentolamine (5.0 × 10-7 mol/l), propranolol (1.0 × 10-6 mol/l), atropine (1.0 × 10-6 mol/l), mepyramine (1.0 × 10-6 mol/l) or cimetidine (1.0 × 10-5 mol/l).
6 In the external carotid and lingual arteries the pattern of activity obtained with methysergide and cyproheptadine was the same as that in the femoral artery, while in the auricular artery the pattern of activity was the same as that in the saphenous vein.
7 The results are consistent with the hypothesis that there are two types of receptor mediating 5-HT-induced vasoconstriction in dog vasculature. One type, characterized by the pattern of activity obtained in the femoral artery, is like the previously described `D-receptor'. The other type, characterized by the pattern of activity obtained in the saphenous vein, has not been described before. The verification of this hypothesis requires the identification of a specific antagonist of 5-HT and methysergide in the saphenous vein.
相似文献 下载免费PDF全文 2 Both intraluminal (I/L) and extraluminal (E/L) histamine potentiated responses to E.S. and to I/L NA to the same extent.
3 Mepyramine alone (2.5 × 10-6 mol/l) had no effect on the response of the ear artery to either stimulus, but in the presence of this concentration of mepyramine, the potentiation by histamine of the response to I/L NA was significantly decreased and that to E.S. was replaced by inhibition.
4 The H1-receptor agonist, 2(2-pyridyl) ethylamine, applied I/L potentiated responses to I/L NA at both concentrations used (5.1 and 51 × 10-7 mol/l), but only potentiated the effects of E.S. at the higher concentration.
5 The H2-receptor antagonist, metiamide (4 × 10-6 mol/l), alone did not alter the extent of potentiation of responses to either E.S. or I/L NA by histamine. This suggests relatively weak H2-receptor activity in the rabbit ear artery. In the presence, but not the absence of metiamide, the potentiation by histamine of the I/L NA response was reversible, an observation suggesting an interaction between metiamide and the non-reversible component of the potentiating effect of histamine.
6 These results are interpreted in terms of postsynaptic H1-receptors which potentiate and presynaptic H2-receptors which inhibit contractile responses in the ear artery.
相似文献 下载免费PDF全文 2. At the low perfusion concentration, the total activity, the radioactivity in the alumina eluates (sum of 3H-dopamine, 3H-noradrenaline and deaminated catechol metabolites) and the concentration of 3H-dopamine. 3H-noradrenaline and the deaminated catechol metabolites were decreased in the hearts of the pretreated rats as compared with the controls. The O-methylated amine metabolites were increased. The deaminated O-methylated metabolites were increased in the experiments with 3H-noradrenaline and decreased in the 3H-dopamine experiments.
3. Uptake of 3H-dopamine and 3H-noradrenaline by the hearts of 6-hydroxydopamine pretreated rats was decreased to a much smaller extent when perfused with the high concentration than with the low concentration.
4. At the high perfusion concentration there was a significant difference between control and pretreated animals with regard to the total radioactivity and the radioactivity in the alumina eluates only. The absolute and relative amounts of metabolites were not significantly changed by pretreatment with the exception of the deaminated catechol metabolites in the 3H-dopamine experiments.
5. It is concluded that neuronal Uptake 1 is greatly impaired in the hearts from rats pretreated with 6-hydroxydopamine, but extraneuronal Uptake 2 remains intact.
相似文献 下载免费PDF全文 2 In rat stomach strips, NT elicited a dose-dependent contractile effect in concentrations varying between 1.3 × 10-9 and 5.4 × 10-7 M.
3 The contractile effect of NT (1.3 and 5.4 × 10-8 M) in this tissue was not modified by atropine (3.4 × 10-7 M), methysergide (2.0 × 10-6 M), a mixture of cimetidine (8.0 × 10-6 M) and diphenhydramine (7.8 × 10-6 M), indomethacin (1.4 × 10-5 M), 8-Leu-angiotensin II (1.0 × 10-6 M), glucagon (2.0 × 10-6 M) or somatostatin (3.0 × 10-7 M).
4 Rat stomach strips desensitized by bradykinin (6.1 × 10-6 M) or substance P (7.4 × 10-6 M) maintained their sensitivities to NT (1.3 and 5.4 × 10-8 M).
5 In guinea-pig atria, NT produced a dose-dependent positive inotropic action in concentrations varying between 5.4 × 10-10 and 2.7 × 10-7 M.
6 The inotropic effect of NT (2.7 × 10-9 M) was not influenced by methysergide (2.8 × 10-6 M), atropine (3.4 × 10-7 M), practolol (1.5 × 10-5 M), 8-Leu-angiotensin II (1.0 × 10-6 M), or indomethacin (1.4 × 10-5 M), but it was reduced by 37% by cimetidine (4.0 × 10-5 and 2.0 × 10-4 M). A combination of cimetidine (4.0 × 10-5 M) and diphenhydramine (3.9 × 10-6 M) did not produce a greater inhibition of NT than cimetidine alone.
7 Atria desensitized by bradykinin (6.1 × 10-6 M) or glucagon (2.0 × 10-6 M) maintained their sensitivities to NT (2.7 × 10-9 M). Substance P was inactive both as an agonist or antagonist of NT.
8 These results suggest the existence of specific NT receptors in rat stomach strips and guinea-pig atria.
9 The data derived from our structure-activity study suggest that the minimum structure required for the full stimulation of NT receptors in these two preparations is H-Arg9-Pro10-Tyr11-Ile12-Leu13-OH. The sequence PyroGlu1-Leu2-Tyr3-Glu4-Asn5-Lys6-Pro7-Arg8- and the amino acids Ile12 and Leu13 appear to contribute mainly to the affinity or binding of NT to its receptor. The chemical groups responsible for the full activation (intrinsic activity) of NT receptors seem to be located in the sequence -Arg9-Pro10-Tyr11.
相似文献Aim:
The sex hormones 17β-estradiol (βES) and progesterone (PRG) induce rapid non-genomic vasodilator effects which could be protective for the cardiovascular system. The purpose of this study was to analyze the mechanisms underlying their vasodilator effect in rat aortic smooth muscle preparations.Methods:
Endothelium-denuded aorta artery rings were prepared from male Wistar rats and incubated in an organ bath. The contractions of the preparation were recorded through isometric transducers. The effects of the hormones on K+ current and L-type Ca2+ current (LTCC) were analyzed by using the whole cell voltage-clamp technique in A7r5 cells.Results:
Both βES and PRG (1–100 μmol/L) concentration-dependently relaxed the endothelium-denuded aortic rings contracted by (–)-Bay K8644 (0.1 μmol/L) or by KCl (60 mmol/L). The IC50 values of the two hormones were not statistically different. The KV channel blocker 4-aminopyridine (2 mmol/L), BKCa channel blocker tetraethylammonium (1mmol/L) and KATP channel blocker glibenclamide (10 μmol/L) did not significantly modify the relaxant effect of the hormones. On the other hand, the blockage of the intracellular βES and PRG receptors with estradiol receptor antagonists ICI 182,780 (1 μmol/L) and PRG receptor antagonist mifepristone (30 μmol/L), respectively, did not significantly modify the relaxant action of the hormones. In A7r5 cells, both the hormones (1–100 μmol/L) rapidly and reversibly inhibited the basal and BAY-stimulated LTCC. However, these hormones had no effect on the basal K+ current.Conclusion:
The vasorelaxant effects of βES and PRG are due to the inhibition of LTCC. The K+ channels are not involved in the effects. 相似文献 下载免费PDF全文 2 Changes in muscle tone were observed in colon and rectum and to a lesser extent in jejunum and ileum of both species. Rat colon and rectum contracted to the peptides. Guinea-pig colon and rectum relaxed after an initial short-lasting contraction.
3 On the rat rectum (D-ala2)met-enkephalin, leu-enkephalin, γ-endorphin, α-endorphin and β-LPH 80-91 caused dose-dependent contractions, their ED50 values being 0.96 × 10-12 mol, 1.05 × 10-11 mol, 1.22 × 10-11 mol, 1.08 × 10-10 mol, 2.65 × 10-10 mol and 6.5 × 10-9 mol, respectively.
4 Naloxone dose-dependently shifted the dose-response curve of met-enkephalin to the right. Atropine, hexamethonium, burimamide, mepyramine, propranolol and indomethacin did not influence the response to met-enkephalin.
5 In the presence of tetrodotoxin, the ED50 for met-enkephalin and the maximal contractor response induced by met-enkephalin, appeared to be increased.
6 The 5-hydroxytryptamine (5-HT) antagonists, methysergide and cyproheptadine, reduced the contractor response in a non-competitive manner. The α-adrenoceptor antagonist phentolamine, in contrast, caused an increase of the maximal response to met-enkephalin of up to 200%. Noradrenergic and tryptaminergic systems, therefore, might be involved in the changes in muscle tone induced by met-enkephalin.
7 These results demonstrate that rectum and colon of guinea-pig and rat are very sensitive to opioid-like peptides.
相似文献Aim:
Platycodin D, the main saponin isolated from Chinese herb Platycodonis Radix, exhibits anticancer activities against various cancer cell lines. Here we evaluated its anticancer action against human hepatocellular carcinoma cells in vitro and in vivo, and elucidated the relationship between platycodin D-induced apoptosis and autophagy.Methods:
The viability of human hepatocellular carcinoma BEL-7402 cells was evaluated with MTT assay, and the apoptosis was examined using Annexin V/PI and Hoechst 33342 staining assays. Monodansylcadaverine (MDC) staining was used to label autophagic vacuoles. The proteins were detected using Western blot analysis. For studying its anticancer action in vivo, platycodin D (5 and 10 mg· kg−1·d−1) was intraperitoneally injected to BEL-7402-bearing mice for 21 days.Results:
Platycodin D (5–40 μmol/L) inhibited the cell proliferation in vitro with IC50 values of 37.70±3.99, 24.30±2.30 and 19.70±2.36 μmol/L at 24, 48 and 72 h, respectively. Platycodin D (5–20 μmol/L) dose-dependently increased BEL-7402 cell apoptosis, increased the Bax/Bcl-2 ratio and the levels of cleaved PARP and cleaved caspase-3, and decreased the level of Bcl-2. Furthermore, platycodin D (5–20 μmol/L) induced autophagy in BEL-7402 cells, as evidenced by formation of cytoplasmic vacuoles, increased amounts of LC3-II, and increased numbers of MDC-positive cells. Pretreatment with the autophagy inhibitor chloroquine (5 μmol/L) or BAF (50 nmol/L) significantly enhanced platycodin D-induced proliferation inhibition and apoptosis. Moreover, platycodin D (20 μmol/L) activated the ERK and JNK pathways in BEL-7402 cells, and simultaneous blockage of the two pathways effectively suppressed platycodin D-induced autophagy and enhanced platycodin D-induced apoptosis. In BEL-7402-bearing mice, platycodin D (10 mg·kg−1•d−1) significantly reduced relative tumor volume with decreased body weight.Conclusion:
Platycodin D not only inhibits the proliferation of BEL-7402 cells but also suppresses BEL-7402 xenograft tumor growth. Platycodin D-induced cell proliferation inhibition and apoptosis are amplified by co-treatment with autophagy inhibitors 相似文献Aim:
To investigate noncovalent interactions between borneol and human serum albumin (HSA) under near-physiological conditions.Methods:
A 65-μm polydimethylsiloxane (PDMS) fiber was selected for sampling. The extraction temperature was kept at 37 °C, and the extraction time was optimized at 10 min. Borneol solutions of different concentrations were equilibrated in 600 μmol/L HSA and 67 mmol/L phosphate buffer solution (pH 7.4, 37 °C) for 24 h prior to solid phase microextraction (SPME) using headspace mode. The binding properties were obtained based on the calculation of extracted borneol amount using gas chromatography (GC) determination.Results:
The headspace SPME extraction method avoided disturbance from the HSA binding matrix. The recovery showed good linearity for the borneol concentrations over the range of 0.4–16.3 μmol/L with a regression coefficient (R2) of 0.9998. The limit of detection and lower limit of quantitation were determined to be 0.01 μmol/L and 0.4 μmol/L, respectively. The binding constant and the percentage binding rate were estimated to be 2.4×103(mol/L)-1 and 59.5%, respectively.Conclusion:
Headspace SPME coupled to GC is a simple, sensitive and rapid method for the study of borneol binding to HSA. The method may be applied in the determination of other protein binding properties in human plasma. 相似文献Aim:
To investigate the cytotoxic effects of piperonal ciprofloxacin hydrazone (QNT4), a novel antibacterial fluoroquinolone derivative, against human hepatocarcinoma SMMC-7721 cells.Methods:
Human hepatocarcinoma cells (SMMC-7721), human breast adenocarcinoma cells (MCF-7) and human colon adenocarcinoma cells (HCT-8) were tested. The effects of QNT4 on cell proliferation were examined using MTT assay. Cell apoptosis was determined using Hoechst 33258 fluorescence staining, TUNEL assay and agarose gel electrophoresis. The topoisomerase II activity was measured using agarose gel electrophoresis with the DNA plasmid pBR322 as the substrate. Mitochondrial membrane potential (Δψm) was measured using a high content screening imaging system. Protein expression of caspase-9, caspase-8, caspase-3, p53, Bcl-2, Bax, and cytochrome c was detected with Western blot analysis.Results:
Treatment with QNT4 (0.625–10 μmol/L) potently inhibited the proliferation of the cancer cells in time- and dose-dependent manners (the IC50 value at 24 h in SMMC-7721 cells, MCF-7 cells and HCT-8 cells was 2.956±0.024, 3.710±0.027, and 3.694±0.030 μmol/L, respectively). Treatment of SMMC-7721 cells with QNT4 (0.2146, 2.964, and 4.600 μmol/L) for 24 h dose-dependently increased the percentage of apoptotic cells, elicited characteristic DNA “ladder” bands, and decreased the mitochondrial membrane potential. QNT4 dose-dependently increased topoisomerase II-mediated DNA breaks while inhibiting DNA relegation, thus keeping the DNA in fragments. Treatment of SMMC-7721 cells with QNT4 significantly increased cytochrome c in the cytosol, and decreased cytochrome c in the mitochondrial compartment. QNT4 (3–7.39 μmol/L) significantly increased the protein expression of p53, Bax, caspase-9, caspase-3, and the cleaved activated forms of caspase-9 and caspase-3 in SMMC-7721 cells. In contrast, the expression of Bcl-2 was decreased, while caspase-8 had no significant change.Conclusion:
QNT4 induced the apoptosis of SMMC-7721 cells via inhibiting topoisomerase II activity and modulating mitochondrial-dependent pathways. 相似文献 下载免费PDF全文 2 Atropine (1 × 10-9 -1 × 10-6M) alone, in the presence of hexamethonium (1 × 10-4M), or phentolamine (1 × 10-6M), inhibited responses to acetylcholine but not to (-)-noradrenaline. The inhibitory effect with the higher concentrations of atropine (1 × 10-8 - × 10-6M), was seen as an increase in the slopes of the concentration-response curves. Atropine (1 × 10-8M) alone inhibited the responses to methacholine and carbachol without altering the slopes of the concentration-response curves.
3 Homatropine (1 × 10-6M) alone had no effect on responses to (-)-noradrenaline and inhibited responses to acetylcholine and methacholine. The inhibitory effect on responses to acetylcholine but not to methacholine, included an increase in the slopes of the concentration-response curves.
4 Neostigmine (1 × 10-6M) alone had no effect on responses to (-)-noradrenaline and potentiated responses to acetylcholine and methacholine. The potentiating effect included an increase in the slopes of the concentration-response curves.
5 In the presence of neostigmine (1 × 10-6M), atropine (1 × 10-9M - 1 × 10-6M) caused a parallel concentration-dependent shift of the concentration-response curves to acetylcholine. The pA2 values, in the presence of neostigmine, were independent of the concentration of atropine and of the agonist (acetylcholine, methacholine, or carbachol) used. In the presence of neostigmine (1 × 10-6M), homatropine (1 × 10-6M) also failed to alter the slopes of the concentration-response curves to acetylcholine and was approximately 100 times less potent than atropine as an antimuscarinic agent.
6 These results illustrate that, in the rat anococcygeus muscle, it is necessary to inhibit acetylcholinesterase before determining the relative potencies of antagonists at muscarinic receptors.
相似文献Aim:
To investigate whether apocynin, a NADPH oxidase inhibitor, produced cardioproteictive effects in Ang II-induced hypertensive mice, and to elucidate the underlying mechanisms.Methods:
C57BL/6 mice were subcutaneously infused Ang II for 4 weeks to mimic cardiac remodeling and fibrosis. Concomitantly the mice were administered apocynin (100 mg·kg−1·d−1) or/and the aldosterone receptor blocker eplerenone (200 mg·kg−1·d−1) via gavage for 4 weeks. Systolic blood pressure (SBP) and heart rate were measured, and transthoracic echocardiography was performed. For in vitro study, cardiac fibroblasts were treated with Ang II (10−7 mol/L) in the presence of apocynin (10−5 mol/L) or/and eplerenone (10−5 mol/L). Immunohistochemistry and Western blotting were used to quantify the expression levels of NADPH oxidase and osteopontin (OPN) proteins in the cells.Results:
Both apocynin and eplerenone significantly decreased SBP, and markedly improved diastolic dysfunction in Ang II-induced hypertensive mice, accompanied with ameliorated oxidative stress and cardiac fibrosis. In the Ang II-treated cardiac fibroblasts, the expression levels of NOX4 and OPN proteins were markedly upregulated. Both Apocynin and eplerenone significantly suppressed the increased expression levels of NOX4 and OPN proteins in the Ang II-treated cells. In all the experiments, apocynin and eplerenone produced comparable effects. Co-administration of the two agents did not produce synergic effects.Conclusion:
Apocynin produces cardioproteictive effects comparable to those of eplerenone. The beneficial effects of apocynin on myocardial oxidative stress and cardiac fibrosis might be mediated partly through a pathway involving NADPH oxidase and OPN. 相似文献2. The β-adrenoceptor antagonist LB46 (2 × 10-8 g/ml) abolished the effect of isoprenaline in reducing vagal bradycardia. LB46 itself did not alter the responses to vagal stimulation.
3. Increase in 86Rb efflux induced by acetylcholine was not affected by isoprenaline.
4. Aminophylline (2·3 × 10-4 g/ml) almost abolished the negative chronotropic effect of vagal stimulation.
5. The `antivagal' effects of isoprenaline and aminophylline may be at a common site beyond the level of the cardiac β-adrenoceptors, perhaps related to cyclic-3′,5′-AMP and/or sodium transport.
相似文献 下载免费PDF全文 2 Each procedure reduced carbachol-induced tone; sympathetic and NANC nerve stimulation were equipotent but both were less effective than sympathomimetic drugs, of which Iso was the better. Both Iso and NA, but not sympathetic nerve stimulation, inhibited the contractions produced by pelvic nerve stimulation in a concentration-dependent manner. Against ACh-induced contractions, only Iso was effective. The effects of NANC nerve stimulation on the motor responses to pelvic nerve stimulation or to ACh were not investigated.
3 The inhibitory effects of sympathetic nerve stimulation, of Iso and of NA were reduced by propranolol (3 × 10-6 M) but unaffected by phentolamine (3 × 10-5 M).
4 In the presence of high (45 mM) concentrations of KCl, Iso and NA produced a concentration-dependent inhibition of tone that was antagonized by propranolol (3 × 10-6 M).
5 Methoxamine (4 × 10-7 to 4 × 10-5 M) and phenylephrine (5 × 10-7 to 5 × 10-5 M) which interact mainly with α1-adrenoceptors, produced only small, transient reductions in carbachol-induced tone which were subject to tachyphylaxis, unlike those produced by Iso and NA. These inhibitory effects were antagonized by phentolamine (3 × 10-6 M) or azapetine (3 × 10-6 M).
6 Phenylephrine (5 × 10-4 M) and high doses (3 × 10-5 M or greater) of NA enhanced the contractile response to pelvic nerve stimulation and, on occasion, produced muscle contraction. These effects were antagonized by phentolamine (3 × 10-6 M).
7 These results suggest that inhibition of the rectococcygeus, a muscle which has no intramural nerve plexus, can be inhibited by stimulation of extrinsic NANC nerves, the transmitter for which is unknown and by sympathetic nerve stimulation via α- and β-adrenoceptors located postsynaptically on the muscle. Excitatory α-adrenoceptors may also be present.
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