BACKGROUND: It is generally accepted that propofol does not inhibit hypoxic pulmonary vasoconstriction (HPV). However, because the previous studies for the effects of propofol on HPV were established in vivo, the effects of physiologic variables could not be ruled out. Therefore, we investigated the effects of various concentrations of propofol on HPV at isolated rat lungs and the relationship of these effects of propofol on HPV and endothelium-derived relaxing factor (EDRF) and an ATP-dependent K+ channel which were candidates as the mechanism of HPV. METHODS: In 30 isolated rat lungs, after three hypoxic challenges for 5 minutes, we administered saline in the control group, N(G)-nitro-L-arginine methyl ester (L-NAME) in the L group and glibenclamide in the G group followed by three hypoxic challenges for 5 minutes. In addition, we studied the effects of various concentrations of propofol on HPV in the three groups. RESULTS: L-NAME and glibenclamide did not alter baseline pulmonary arterial pressure but L-NAME significantly enhanced HPV. Clinical concentrations of propofol did not affect HPV and high concentrations of propofol inhibited HPV. The pretreatment of L-NAME and glibenclamide did not alter the inhibition of HPV even at high concentrations of propofol. CONCLUSIONS: The EDRF and ATP-dependent K+ channel did not largely contribute to baseline pulmonary arterial tone but EDRF might be released and downregulate HPV. Clinical concentrations of propofol did not inhibit HPV but high concentrations of propofol inhibited HPV. In addition, the mechanism of inhibition of HPV at high concentrations of propofol did not relate to the EDRF pathway and ATP-dependent K+ channel.
Animals ; Arterial Pressure ; Endothelium-Dependent Relaxing Factors ; Glyburide* ; Lung* ; NG-Nitroarginine Methyl Ester* ; Propofol* ; Rats* ; Vasoconstriction*

PURPOSE: We investigated the effects of the superoxide radical on rat whole bladder contractility with duroquinone (superoxide radical generator, Dq) and diethyldithiocarbamate (superoxide dismutase inhibitor, DETCA), and the effects of ginseng saponin (GS) against superoxide radical injury. MATERIALS AND METHODS: Isometric tension changes of isolated rat whole bladders were recorded in an organ bath using a force transducer. The acute effects of Dq and Dq preincubated with DETCA were assessed on resting tension, electrical field stimulation, and bethanechol-, ATP-, and KCl-induced contraction. The effects of Dq and Dq preincubated with DETCA in the presence of sodium nitroprusside and GS were investigated. RESULTS: The resting tension of the muscle was not changed by Dq and Dq preincubated with DETCA. Dq had a harmful effect on only ATP- and KCl-induced detrusor contraction, whereas Dq pretreated with DETCA attenuated the induction of detrusor contraction which was reduced in response to the exogenous NO including GS. In the presence of L-NAME, the effects of GS reduced the Dq-induced inhibition on the detrusor contractility. CONCLUSIONS: It is suggested that the superoxide radical may be the cause of voiding difficulty. GS, as a NO synthesis stimulator, seems to act as a scavenger of the superoxide anion. However further study on the effect of each subfraction of GS is needed for clinical application.
Animals ; Baths ; Ditiocarb ; NG-Nitroarginine Methyl Ester ; Nitroprusside ; Panax* ; Rats* ; Saponins* ; Superoxides* ; Transducers ; Urinary Bladder*

The present study was aimed to investigate whether and to what extent hypertension affects the relaxation of the corpus cavernosum. The corpus cavernosum was isolated from 12-week 2- kidney, 1-clip hypertensive rats. The corporal strips were isolated and suspended longitudinally in an organ bath. They were precontracted with phenylephrine, and their responses to electrical field stimulation (EFS) were examined. EFS caused a frequency-dependent contraction (60%) or relaxation (40%) of the corpus cavernosum precontracted with phenylephrine. The contraction response was inhibited or abolished and only frequency-dependent relaxation appeared in the presence of atropine (0.00001mol/L) and guanethidine (0.00001mol/L). The relaxation response to EFS of the corporal preparation precontracted with phenylephrine was attenuated or abolished in the presence of L-NAME (0.0001mol/L). The corporal preparation from the hypertensive rats also showed a frequency-dependent relaxation, however, the degree of which was lower at a low frequency of stimulation than that from the normotensive control. These results suggest that endothelium-derived nitric oxide released upon neural stimulation partly mediate the relaxation of the corpus cavernosum. It is also suggested that hypertension is associated with a partly attenuated relaxation response to EFS.
Animals ; Atropine ; Baths ; Guanethidine ; Hypertension ; Kidney ; NG-Nitroarginine Methyl Ester ; Nitric Oxide ; Phenylephrine ; Rats* ; Relaxation

BACKGROUND: Endotoxins play important roles in the pathophysiologic alterations associated with sepsis so the authors examined the effects of hydroxocobalamin, NW-nitro-L-arginine-metyl ester (L-NAME) and aminoguanidine on thiopental-induced contractile responses of lipopolysaccharide (LPS)-treated and control rat aortic rings. METHODS: Aortic ring preparation was obtained from LPS-treated (1.5mg/kg, i.p. for 18h) rats. Cumulative doses of thiopental (10-4~3x10- 3M) were added to construct contraction response curves. Hydroxocobalamin (10-5M), L-NAME (10-6M) or aminoguanidine (10-6M) were added as NO scavenger or as NOS inhibitors. Contraction curves by cumulative doses of thiopental (10-4~3x10-3M) were remeasured after treatment of NO scavenger or NOS inhibitors. Statistical significances (p<00.05) were analyzed according to data characteristics by Student's t-test, paired t-test or ANOVA. RESULTS: The vascular responses of cumulative thiopental (10-4~3x10 3M) administration were dose- dependent contraction and LPS-treated rat was less contracted (p<00.05). There was significant increment on vascular contraction induced by thiopental after hydroxocobalamin pretreatment in LPS-treated rat (p<0.05), in spite of L-NAME, aminoguanidine pretreatment was failed to increase contractile forces in control and LPS-treated rats. CONCLUSIONS: From these results, viewed from maintenance of vasomotor tone in septic state, it is suggested that hydroxocobalamin may be candidate for vasopressor during usual induction of general anesthesia.
Anesthesia, General ; Animals ; Aorta, Thoracic* ; Endotoxins ; Hydroxocobalamin* ; NG-Nitroarginine Methyl Ester ; Rats* ; Sepsis ; Thiopental

PURPOSE: To evaluate the effect of nitric oxide (NO) on the survival of R28 cells. METHODS: After immunostaining for GFAP, vimentin, S-100, and neurofilament, R28 cells were exposed to S-nitroso-N-acetyl-D, L-penicillamine (SNAP) at various concentrations, with and without the NO inhibitor, Nomega-Nitro-L-arginine methyl ester (L-NAME) for 1 and 3 days. Cellular survival of R28 cells and the production of NO were quantified by rapid colorimetric assays using the MTT and Griess assay, respectively. To evaluate the effect of serum, 10% serum or serum-free media were used separately. RESULTS: R28 cells showed strong immunoreactivity to GFAP and vimentin compared to S-100 or neurofilament. SNAP inhibited the survival of R28 cells in a dose-dependent manner, and this effect of NO on the cellular survival was abolished by L-NAME. These results were similar after exposure for 1 and 3 days, regardless of the presence of serum in the media. CONCLUSIONS: The current results suggest that NO decreased the survival of R28 cells. Further studies are necessary to evaluate the mechanism of cytotoxicity of the R28 cells.
Culture Media, Serum-Free ; NG-Nitroarginine Methyl Ester ; Nitric Oxide ; Vimentin

PURPOSE: To investigate the effect of hypoxia on the survival and nitric oxide (NO) production of cultured trabecular meshwork (TM) cells. METHODS: After inducing chemical hypoxia with sodium cyanide, the survival and nitrite production of the primarily cultured porcine TM cells were assessed with MTT and Griess assays. The effect of NOS inhibitor, N(omega)-Nitro-L-arginine methyl ester (L-NAME), was also assessed. Flow cytometry using annexin/PI was done to evaluate apoptosis. RESULTS: Chemical hypoxia decreased TM cell survival significantly (p<0.05) with increased NO production. This hypoxia-induced antiproliferative effect was abolished by L-NAME (p<0.05). Flow cytometric analysis revealed that hypoxia induced apoptosis of TM cells, which was inhibited by L-NAME. CONCLUSIONS: Hypoxia decreases the survival of TM cells and induced apoptosis, accompanied by increased NO production. The hypoxia-induced decreased survival of TM cells may be mediated by NO.
Anoxia* ; Apoptosis ; Cell Survival ; Flow Cytometry ; NG-Nitroarginine Methyl Ester ; Nitric Oxide* ; Sodium Cyanide ; Trabecular Meshwork*

PURPOSE: To investigate the effects of nitric oxide (NO) on the permeability of cultured human trabecular meshwork cell (HTMC) monolayer. METHODS: HTMCs were cultured until confluency in the Transwell inner chamber and then exposed to 0, 10 or 100 microm S-nitroso-N-acetyl-DL-penicillamine (SNAP) and 0.5 mm L-NG-Nitroarginine methyl ester (L-NAME) for 24 hours. Permeabilities of carboxyfluorescein through the HTMC monolayer were measured using a spectrofluorometer after 2 hours in the outer chamber. Cellular viabilities and production of NO were assessed using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and Griess assay, respectively. RESULTS: The cellular survival was not affected by 10 or 100 microm SNAP (p > 0.05) but NO production increased in a dose-dependent manner (p < 0.05). SNAP significantly increased the permeability of carboxyfluorescein through the HTMC monolayer in a dose-dependent manner compared with non-exposed control (p < 0.05). The endothelial NO synthase inhibitor L-NAME abolished SNAP-induced increase of the carboxyfluorescein permeability (p > 0.05). CONCLUSIONS: NO increased the permeability of carboxyfluorescein through the HTMC monolayer in a dose-dependent manner. Thus, NO could increase trabecular outflow by increasing the permeability of trabecular cell layer in addition to trabeular messwork (TM) relaxation.
Humans ; NG-Nitroarginine Methyl Ester ; Nitric Oxide Synthase ; Nitric Oxide* ; Permeability* ; Relaxation ; Trabecular Meshwork*

OBJECTIVES: The present study was designed to investigate the effect of ginseng saponin and its major active metabolite on the HPA axis under acute stress-i.c.v. injection stress, and immobilization stress, and to examine whether nitric oxide is involved in the mechanism of ginseng saponin on the HPA axis under acute stress. METHODS: In the experiment to study the effect of ginseng on HPA axis during stress, various dose of GTS were injected intracerebroventricularly(i.c.v.) or intraperitoneally(i.p.). Plasma corticosterone levels were measured 30 min after the i.c.v. injection stress. Immobilization stress was applied for 30 min and then blood was cellected for the assays of plasma corticosterone levels immediately after the completion of immobilization stress. To determine the active ginsenosides that can affect the stressinduced plasma corticosterone levels, various dose of each gisendosides(Rb1, Rb2, Rc, Re, Rf, Rg1, 20(S)-Rg3, and 20(R)-Rg3) were injected i.c.v. or i.p.. In the experiment to determine the involvement of the nitric oxide in the inhibitory effect of ginseng on the HPA, NG-Nitro-L-arginine methyl ester(L-NAME) and ginsenosides were coadministered i.c.v. or i.p., and plasma corticosterone levels were measured 30 min after stress was applied. RESULTS: First, the present study showed that ginseng total saponin, ginsenoside Rg3(S form), and ginsenoside Rc administered i.c.v. attenuated the intracerebroventricular injection stress-induced increase in plasma corticosterone levels, and these effects were removed by nitric oxide co-injection. Second, ginseng total saponin and ginsenoside Rc administered i.p. attenuated the immobilization stress-induced increase in plasma corticosterone levels, but ginsenoside Rg3(S form) did not attenuate the immobilization stress-induced increase in plasma corticosterone levels. The attenuative effects of ginseng total saponin and ginsenoside Rc in the immobilization stress-induced increase in plasma corticosterone levels were not affected by L-NAME co-injection. CONCLUSION: This study suggests that ginseng saponin attenuated stress-induced increase in plasma corticosterone levels and these effects were mediated by different mechanisms according to the components of ginseng saponin, and routes of administration.
Animals ; Axis, Cervical Vertebra ; Corticosterone* ; Ginsenosides ; Immobilization ; Mice* ; NG-Nitroarginine Methyl Ester ; Nitric Oxide ; Nitroarginine ; Panax* ; Plasma* ; Saponins*

BACKGROUND: The spinal administration of neostigmine has been shown to produce analgesia, but this analgesia is limited by adverse effects. This study was designed to determine whether intra-articular neostigmine results in an analgesic effect in a rat inflamed knee joint model, and to investigate the possible involvement of nitric oxide in neostigmine-induced analgesia. METHODS: Male Sprague Dawley rats were divided into three groups; control group, neostigmine group (1, 3, 10micro gram), and L-NAME group (neostigmine 1, 3, 10micro gram + L-NAME 500micro gram). Inflammation was induced by injecting 2% carageenan into the right knee joint. Intraarticular drugs were injected at an hour after the injection of carageenan. Effects of these drugs were assessed before and at 4, 8, 12, 24, 60, and 120 hours after inflammation using a Dynamic plantar aesthesiometer. RESULTS: There were significant differences between the neostigmine 3, and 10micro gram group and the control group. There were no significant differences between the neostigmine group and the L-NAME group except for in the neostigmine 10micro gram L-NAME group at 24 hours. There were no significant differences between the neostigmine 3micro gram L-NAME group and the control group. This result shows that injection of L-NAME partially reverses the anlgesic effects of the neostigmine. CONCLUSIONS: Intra-articular neostigmine results in an analgesic effect at the site of inflammation. Although this study could not prove the involvement of nitric oxide in the peripheral analgesic effect of neostigmine, it demonstrates the possible involvement of nitric oxide in neostigmine-induced analgesia.
Analgesia ; Animals ; Arthritis* ; Humans ; Inflammation ; Knee Joint ; Male ; Neostigmine* ; NG-Nitroarginine Methyl Ester* ; Nitric Oxide ; Rats* ; Rats, Sprague-Dawley

BACKGROUND: Several investigations have studied hypoxic pulmonary vasoconstriction (HPV) during endotoxemia and there is an increase in nitric oxide (NO) in pulmonary vessels. However, these studies yielded conflicting or at times contradictory results, since reference has been made to both enhancement and inhibition of HPV. Our objective was to determine the changes of hypoxic pulmonary vasoconstriction on the isolated blood-perfused lung of endotoxemic rats. METHODS: Pulmonary arterial pressure (PAP) was measured in a blood-perfused lung preparation from Sprague-Dawley rats in normoxia (21% O2, 5% CO2, balanced N2) and hypoxia (5% O2, 5% CO2, balanced N2). We studied the effect of normoxia and hypoxia in a control group, Escherichia coli lipopolysaccharide group (LPS) and LPS with N omega-nitro-L-arginine methyl ester group (L-NAME). RESULTS: The Baseline PAP was higher in LPS (15.0+/-4.0 mmHg) compared with control group (10.9+/-2.9 mmHg) and L-NAME (11.1+/-3.6 mmHg). In hypoxia, HPV was higher in L-NAME (109.6+/-100.2%) compared with control group (59.9+/-31.6%) and LPS (58.8+/-33.8%)(P<0.05). CONCLUSIONS: We conclude that NO is an important factor to impair HPV during endotoxemia.
Animals ; Anoxia ; Arterial Pressure ; Endotoxemia ; Escherichia coli ; Lung* ; NG-Nitroarginine Methyl Ester ; Nitric Oxide ; Rats* ; Rats, Sprague-Dawley ; Vasoconstriction*