OBJECTIVETo investigate the effect of emodin on the contraction of jejunum smooth muscle and its underlying mechanisms.

METHODSRats were randomly divided into 7 groups (n = 6): control group, emodin group (1, 5, 10, 20 micromol/L), propranolol (PRO) plus emodin group, glibenclamide (GLI) plus emodin group, NG-Nitro-L-arginine Methyl Ester (L-NAME) plus emodin group, calcium free control group and calcium free emodin group. The rats were sacrificed by cervical dislocation and the small intestine was isolated. The jejunum segment specimens were mounted on an Organ Bath System with a tension transducer. The effect of emodin on contraction of jejunum smooth muscle was measured by BL-420E+ biological signal processing system and the amplitude (AM), tension (TE) and frequency (FR) of contraction were determined.

RESULTS(1) Emodin inhibited the tension and amplitude of jejunum smooth muscle contraction in a dose-dependent manner (P < 0.05, P < 0.01) while the frequency was not obviously influenced. (2) PRO (P < 0.05) or GLI (P < 0.01) partly abolished the inhibitory effect of emodin on jejunum smooth muscle. (3) L-NAME had no obvious effect on the inhibitory effect of emodin. (4) Emodin attenuated the contraction of jejunum smooth muscle induced by calcium chloride application into calcium free K-H solution (P < 0.01).

CONCLUSIONEmodin obviously inhibits the amplitude and tension, while has no influence on the frequency of jejunum smooth muscle contraction in rats. Activation of beta adrenergic receptor, open of ATP sensitive potassium channels, and inhibition of the extracellular calcium influx through calcium channels of smooth muscle cell membrane might be involved in the process.

Animals ; Calcium Signaling ; Emodin ; pharmacology ; Glyburide ; pharmacology ; Jejunum ; drug effects ; Muscle Contraction ; drug effects ; Muscle, Smooth ; drug effects ; NG-Nitroarginine Methyl Ester ; pharmacology ; Propranolol ; pharmacology ; Rats

OBJECTIVETo observe the effects of nitric oxide(NO) on the DNA ploidy of germ cells and to evaluate the role of NO in modulating spermatogenesis by using SNP, a donor of NO and N-nitro-l-arginine-mythel-ester(L-NAME), an inhibitor of nitric oxide synthese(NOS) in rats physically in vivo.

METHODSForty adult male, Sprague-Dawley rats (60-70 days) were divided into four groups, and injected ultraperitoneally with one of the following agents (once a day, for 12 days): SNP, L-NAME and SNP + L-NAME with normal saline. Two hours after the last injection the rats were sacrificed. The sera were collected and stored at -70 degrees C for subsequent hormone assay. The concentration of serum testosterone was measured by radioimmunoassay. Serum NOx- (nitrite/nitrate) concentration was measured by Greiss method. DNA of spermatogenic cells was detected by flow cytometry(FCM), and the percentage of 1c, 2c and 4c germ cells calculated.

RESULTSIn the SNP treatment group, the serum concentration of NOx- was higher, testosterone concentration was lower and the number of 1c cells was smaller compared with the control group. However, in rats treated with L-NAME, the concentration of NOx- was significantly lower, testosterone concentration was higher and the number of 1c cells was larger compared with the control group(P < 0.01). No changes were observed in the SNP + L-NAME group.

CONCLUSIONEnhancing ectogenous NO will suppress spermatogenesis while inhibiting NO productive pathway will promote it.

Animals ; DNA ; analysis ; Flow Cytometry ; Male ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; physiology ; Nitroprusside ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Spermatogenesis ; drug effects

The role of nitric oxide during neonatal sepsis is complex. We tested the hypothesis that nonselective inhibition of nitric oxide synthase with N(w) -nitro-L-arginine methyl ester (L-NAME) is detrimental during the early phase of experimental sepsis in the newborn piglet. Newborn piglets were divided into four groups: 6 in the control group, 6 in the L-NAME control group, 12 in the sepsis group (SG), and 11 in the sepsis with L-NAME group (NS). Sepsis was induced by intravenous injection of 10(8) colony forming units of Escherichia coli. L-NAME 10 mg/kg was given intravenously 60 min before the induction of sepsis. The survival rate of piglets after 4 hr was 27% in NS, while it was 100% in other groups. Systemic hypotension, observed in both SG and NS, were more profound in NS. Leukopenia was observed in both SG and NS. Thrombocytopenia, prolongation of prothrombin time and activated partial thromboplastin time, and increase in thrombin-antithrombin complexes were observed only in NS. Decreased PaO2 /FiO2 ratio, arterial pH and base excess, and increased blood lactate levels observed in both SG and NS, but were more profound in NS. These findings suggest that nonselective inhibition of nitric oxide synthase with L-NAME is detrimental during the early phase of experimental neonatal sepsis.
Animals ; Animals, Newborn ; Enzyme Inhibitors/pharmacology ; Escherichia coli/*metabolism ; NG-Nitroarginine Methyl Ester/*pharmacology ; Sepsis/*drug therapy ; Support, Non-U.S. Gov't ; Swine ; Time Factors

The aim of the present study is to explore the interaction of nitric oxide (NO) and nicotinic acetylcholine receptor (nAChR) on learning and memory of rats. Rats were intracerebroventricularly (i.c.v.) injected with L-arginine (L-Arg, the NO precursor) (L-Arg group) or choline chloride (CC, an agonist of α7nAChR) (CC group), and with combined injection of L-Arg and CC (L-Arg+CC group), and methyllycaconitine (MLA, α7nAChR antagonist) or N(ω)-nitro-L-arginine methylester (L-NAME, nitric oxide synthase inhibitor) i.c.v. injected first and followed by administration of L-Arg combined with CC (MLA+L-Arg+CC group or L-NAME+L-Arg+CC group), respectively, and normal saline was used as control (NS group). The learning and memory ability of rats was tested with Y-maze; the level of NO and the expressions of neuronal nitric oxide synthase (nNOS) or α7nAChR in hippocampus were measured by NO assay kit, immunohistochemistry or Western blot. The results showed that compared with L-Arg group or CC group, the rats' learning and memory behavioral ability in Y-maze was observably enhanced and the level of NO, the optical density of nNOS-like immunoreactivity (LI) or α7nAChR-LI in hippocampus were significantly increased in L-Arg+CC group; Compared with L-Arg+CC group, the ability of learning and memory and the level of NO as well as the expressions of nNOS-LI or α7nAChR-LI were obviously decreased in MLA+L-Arg+CC group or in L-NAME+L-Arg+CC group. In conclusion, i.c.v. administration of L-Arg combined with CC significantly improved the action of the L-Arg or CC on the content of NO and the nNOS or α7nAChR expressions in hippocampus along with the learning and memory behavior of rats; when nNOS or α7nAChR was interrupted in advance, the effects of L-Arg combined with CC were also suppressed. The results suggest that there are probably synergistic effects between NO and nAChR on learning and memory.
Animals ; Enzyme Inhibitors ; pharmacology ; Hippocampus ; physiology ; Learning ; Memory ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; physiology ; Nitric Oxide Synthase Type I ; physiology ; Rats ; alpha7 Nicotinic Acetylcholine Receptor ; physiology

OBJECTIVETo explore if the hypoxia/reoxygenation-induced increased activity and expression of PTP-1B in neonatal rat cardiomyocytes are mediated by nitric oxide (NO).

METHODSNeonatal rat cardiomyocytes were isolated and randomly divided into 4 groups: normal group (N group); hypoxia/reoxygenation group (H/R group); N(omega)-nitro-l-arginine methylester treated group (L-NAME group); hypoxia/reoxygenation plus L-NAME group (L-NA + H/R group). PTP-1B activity in cardiomyocytes was determined spectrophotometrically at 405 nm, PTP-1B expression in cardiomyocytes was detected by Western blot.NO and LDH concentrations in cell medium were also assayed.

RESULTSPTP-1B activity and expression in cardiomyocytes was significantly higher in the H/R group as compared to the N group and this increase could be blocked by cotreatment with L-NAME. As compared to H/R group, nitric oxide and LDH concentrations in cell medium were significantly decreased in the L-NA + H/R group (NO concentration: H/R group, 368% +/- 13% and L-NA + H/R group, 61% +/- 7%, P < 0.005; LDH concentration: H/R group, 41.2 +/- 6.7 and L-NA + H/R group, 23.6 +/- 4.8, P < 0.05).

CONCLUSIONSThis study showed that pretreatment with L-NAME, a non-selective inhibitor of NOS, prevented the hypoxia/reoxygenation-induced increase in PTP-1B activity and expression in cardiomyocytes, suggesting PTP-1B activation during hypoxia/reoxygenation was mediated by nitric oxide.

Animals ; Cell Hypoxia ; Cells, Cultured ; Myocytes, Cardiac ; cytology ; metabolism ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; metabolism ; Rats

BACKGROUNDPreeclampsia (PE) is a multifactorial pregnancy complication. Maternal underlying condition and adverse factors both influence the pathogenesis of PE. Abnormal lipid metabolism as a maternal underlying disease may participate in the occurrence and development of PE. This study aimed to observe the effects of adverse factors on PE-like symptoms of pregnant mice with genetic abnormal lipid metabolism.

METHODSApolipoprotein C-III (ApoC3) transgenic mice with abnormal lipid metabolism were subcutaneously injected with L-arginine methyl ester (L-NAME) or normal saline (NS) daily starting at Day 7 or 16 of pregnancy (ApoC3+L-NA and ApoC3+NS groups), and wild-type (WT) mice served as a control (WT+L-NA and WT+NS groups). All mice were subdivided into early and late subgroups by injection time. The mean arterial pressure (MAP) and urinary protein were measured. Pregnancy outcomes, including fetal weight, placental weight, live birth rate, and fetal absorption rate, were analyzed. Pathologic changes in the placenta were observed by hematoxylin-eosin staining. One-way analysis of variance, t-test, and χ(2) test were used for statistical analysis.

RESULTSMAP significantly increased for ApoC3+NS groups compared with WT+NS groups (P < 0.05), without significant difference in urine protein. Following L-NAME injection, MAP and urinary protein significantly increased for ApoC3+L-NA and WT+L-NA compared with the corresponding NS groups (P < 0.05), and the increase for ApoC3+L-NA was more obvious. Urinary protein levels in early ApoC3+L-NA and WT+L-NA significantly increased compared with the corresponding late groups (P < 0.05). Fetal absorption rate significantly increased and fetal and placental weights significantly decreased in early ApoC3+L-NA and WT+L-NA compared with the corresponding NS groups (P < 0.05), without significant difference in late ApoC3+L-NA and WT+L-NA groups. Fetal weight in early ApoC3+L-NA was significantly lower than in early WT+L-NA group (P < 0.05). Morphologic examination of placentas from early ApoC3+L-NA and WT+L-NA groups showed varying degrees of fibrinoid necrosis.

CONCLUSIONSApoC3 transgenic mice with abnormal lipid metabolism showed gestational hypertension. Adverse factors and early effect time could aggravate the PE-like symptoms for ApoC3 transgenic mice.

Animals ; Apolipoprotein C-III ; genetics ; metabolism ; Female ; Lipid Metabolism ; drug effects ; genetics ; Male ; Mice ; Mice, Transgenic ; NG-Nitroarginine Methyl Ester ; pharmacology ; Pre-Eclampsia ; genetics ; metabolism ; Pregnancy

To investigate the effects of nitric oxide (NO) on the pleural lymphatic stomata and lymph absorption from the pleural cavity, the NOS (nitric oxide synthase) inhibitor N(omega)-nitro-L-arginine-methyl-ester (L-NAME) and the NO donor isosorbide dinitrate (ISDN) were injected into the peritoneal cavity of the rats respectively. Trypan blue was used as a tracer. Then the concentrations of NO and trypan blue in the blood serum were measured, and the ultrastructural changes in pleural lymphatic stomata were observed under a scanning electron microscope (SEM) and studied by a computer image processing system attached to SEM. It turned out that the concentration of NO in the serum was 49.34+/-18.47 micromol/L, and the area and density of the pleural lymphatic stomata were 6.80+/-1.13 microm(2) and 170.24+/-66.60 /0.1 mm(2) respectively in the NO donor group. The concentration of NO reduced to 17.72+/-6.58 micromol/L, and the area and density of the pleural lymphatic stomata were 5.72+/-1.54 microm(2) and 61.71+/-12.73/0.1 mm(2) in the NOS inhibitor group. We found that the area and density of the pleural lymphatic stomata were positively correlated with the NO quantity. After the tracer was injected into the pleural cavity, the NO donor group exhibited a higher trypan blue concentration than the control group. The ability of the pleura to absorb trypan blue was enhanced because of the large opening of the stomata. It is suggested that NO can increase lymph absorption of the pleura by relaxing pleural lymphatic stomata.
Animals ; Lymphatic System ; physiology ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; blood ; Nitric Oxide Synthase ; antagonists & inhibitors ; Peritoneal Stomata ; ultrastructure ; Rats

The effect of systemic administration of nonspecific nitric oxide synthase inhibitor (N(omega)-nitro-L-arginine methyl ester, L-NAME) on morphine analgesia tolerance was observed by using the thermal tail-flick method, and the roles of NO and NMDA receptors in morphine analgesia tolerance were evaluated on the basis of the expressions of nNOS mRNA, NR1A mRNA and NR2A mRNA in spinal cord and midbrain. Thirty-six healthy adult Sprague-Dawley rats were randomly divided into six groups (6 rats per group). Group 1, control group, received a subcutaneous (s.c.) injection of normal saline (1 ml); Groups 2, 3, 4, 5 and 6, the treatment groups received s.c. injection of L-NAME 10 mg/kg, L-NAME 20 mg/kg, morphine 10 mg/kg, L-NAME 10 mg/kg + morphine 10 mg/kg, and L-NAME 20 mg/kg + morphine 10 mg/kg, respectively. All rats received s.c. injections twice per day (8:00 and 17:00). The tail-flick latency (TFL) was measured in each rat before the injection as a baseline value, and then TFL at 50 min after the 1st injection every day as the measuring values. The animals (except for groups 2 and 5) were decapitated at 80 min after the last injection on the 8th day. The spinal segments and midbrain were removed for analysis of nNOS mRNA, NR1A mRNA and NR2A mRNA expressions by the RT-PCR method. The results showed that TFL remained unchangeable in group 2 compared with baseline value during the 7-day observation, while increased significantly on the 7th day in group 3. In group 4, TFL was longest on the 1st day, then decreased gradually from the 2nd day to the 6th day, and restored to the baseline value on the 6th day. In group 5, TFL showed a decreasing tendency during the 7-day observation, but was still significantly longer than the baseline value on the 7th day. The changes of TFL obtained in group 6 were similar to those in group 5. The results of RT-PCR showed that as compared with group 1, nNOS mRNA expressions in spinal cord and midbrain were significantly down-regulated in group 3, but the expressions of the NR1A mRNA and NR2A mRNA in both groups were similar, while the nNOS mRNA, NR(1A) mRNA and NR(2A) mRNA expressions were all significantly up-regulated in group 4. As compared with group 4, the expressions of nNOS mRNA, NR(1A) mRNA and NR(2A) mRNA were significantly inhibited in group 6. These results suggest that the expressions of nNOS and NMDA receptors in spinal cord and midbrain were significantly up-regulated in the rats with morphine analgesia tolerance. Chronic co-administration of L-NAME could effectively inhibit the morphine-induced overexpressions of nNOS and NMDA receptors, and postpone the development of morphine analgesia tolerance. Based on the results of this study, it is concluded that NO/NMDA receptor in spinal cord and midbrain is closely related to the development of morphine analgesia tolerance.
Analgesia ; Animals ; Drug Tolerance ; Mesencephalon ; metabolism ; Morphine ; pharmacology ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide Synthase ; antagonists & inhibitors ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; metabolism ; Spinal Cord ; metabolism ; Up-Regulation

Hypoxic pulmonary vasoconstriction (HPV), a unique response of pulmonary circulation, is critical to prevent hypoxemia under local hypoventilation. Hypoxic inhibition of K+ channel is known as an important O2-sensing mechanism in HPV. Carbon monoxide (CO) is suggested as a positive regulator of Ca2+-activated K+ channel (BK(Ca)), a stimulator of guanylate cyclase, and an O2-mimetic agent in heme moiety-dependent O2 sensing mechanisms. Here we compared the effects of CO on the HPV (Po2, 3%) in isolated pulmonary artery (HPV(PA)) and in blood-perfused/ventilated lungs (HPV(lung)) of rats. A pretreatment with CO (3%) abolished the HPV(PA) in a reversible manner. The inhibition of HPV(PA) was completely reversed by 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ), a guanylate cyclase inhibitor. In contrast, the HPV(lung) was only partly decreased by CO. Moreover, the partial inhibition of HPV(lung) by CO was affected neither by the pretreatment with ODQ nor by NO synthase inhibitor (L-NAME). The CO-induced inhibitions of HPV(PA) and HPV(lung) were commonly unaffected by tetraethylammonium (TEA, 2 mM), a blocker of BK(Ca). As a whole, CO inhibits HPV(PA) via activating guanylate cyclase. The inconsistent effects of ODQ on HPV(PA) and HPV(lung) suggest that ODQ may lose its sGC inhibitory action when applied to the blood-containing perfusate.
Animals ; Anoxia/*physiopathology ; Carbon Monoxide/*pharmacology ; Guanylate Cyclase/antagonists & inhibitors/metabolism ; NG-Nitroarginine Methyl Ester/chemistry/pharmacology ; Nitric Oxide Synthase/antagonists & inhibitors/metabolism ; Oxadiazoles/chemistry/pharmacology ; Pulmonary Artery/*physiopathology ; Quinoxalines/chemistry/pharmacology ; Rats ; Tetraethylammonium/chemistry/pharmacology ; Vasoconstriction/*drug effects/physiology

OBJECTIVETo demonstrate the vasodilatation activity of the coumarin-containing Angelica dahurica var. formosana and to further analyze active components in the herb extracts.

METHODS(1) The vasodilatation effects induced by different extracts (cyclohexane, ethyl acetate, acetone, methanol, 95 % ethanol and water) of Angelica dahurica var. formosana on mouse thoracic aorta pre-contracted with phenylephrine were investigated. (2) The amount of imperatorin and isoimperatorin in each extract was measured by high-performance liquid chromatography. (3) The vasodilatation effects of imperatorin and isoimperatorin on mouse thoracic aorta were compared using the same in vitro method. (4) The vasodilatation mechanism of imperatorin in the mouse thoracic aorta pre-contracted with phenylephrine was studied using the methods of denuded endothelium, NG-nitro-L-arginine methylester (L-NAME, a nitric oxide synthase inhibitor), and propranolol.

RESULTS(1) The cyclohexane and ethyl acetate extracts of Angelica dahurica var. formosana decreased the maximal response of phenylephrine-induced mouse thoracic aorta contraction dose-dependently, with 50% inhibiting concentration (IC(50)) values of 35.3+/-12.4 mg/L and 40.5+/-12.0 mg/L, respectively. The vasodilatation effect of imperatorin and isoimperatorin was dose-dependent. (2) The cyclohexane extract, showing the strongest vasodilatation effect, possessed the highest contents of imperatorin (4.09%) and isoimperatorin (0.27%, w/w). There was a correlation between the vasodilatation activity and the contents of imperatorin and isoimperatorin in the extracts. (3) The vasodilatation effect of imperatorin was about 4-fold stronger than that of isoimperatorin. (4) The vasodilatation effect of imperatorin was signifificantly attenuated to 24.88%+/-4.06% in the denuded endothelium group compared with the intact endothelium group. And 1 mmol/L L-NAME reduced the imperatorin-induced vasorelaxation by 32.18 %+/-11.29 %.

CONCLUSIONSThe principal effective component of Angelica dahurica var. Formosana was found to be imperatorin. Imperatorin-induced vasodilatation is at least partially regulated by nitric oxide, and has no correlation to beta-receptor.

Angelica ; chemistry ; Animals ; Chromatography, High Pressure Liquid ; Endothelium, Vascular ; physiology ; Furocoumarins ; analysis ; pharmacology ; Male ; Mice ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; physiology ; Phenylephrine ; pharmacology ; Plant Extracts ; pharmacology ; Propranolol ; pharmacology ; Vasodilation ; drug effects