Temporal changes in postural sway caused by ultrashort-acting hypnotics: triazolam and zolpidem

Two ultrashort-acting hypnotics, triazolam 0.25 mg and zolpidem 10 mg, were studied for their effects on equilibrium function in humans. Eight healthy male subjects participated in a double-blind, placebo-controlled study after informed consent. They subjected to static equilibrium tests, oculomotor tests and an assay of drug concentrations in the blood. Zolpidem was statistically significant in postural sway in tandem stance test, as defined by parametric values of tracing sum length and polygonal area of foot pressure center measured by a gait analysis system. In the tandem stance test, triazolam was statistically significant in postural sway only as defined by the polygonal area. However, in the Romberg test, the only statistically significant difference in zolpidem use was observed in polygonal area values. Blood concentrations of triazolam and zolpidem were found to closely correlate with the extent of postural sway in both tandem stance and Romberg tests. In this study, zolpidem with minimal muscle-relaxant effect incurred imbalance more extensively than triazolam, which is known for its effect of muscle relaxation. In addition, gaze deviation nystagmus was observed only in zolpidem use in 5 of 8 subjects (62.5%). From these results, it is suggested that in the use of hypnotics, sway derives from the suppression of the central nervous system relevant to awakening rather than from muscle relaxation. The prior reference to blood concentrations of hypnotics should help improve safety care in minimizing loss of balance control and possible fall.

Effects of edaravone on human neutrophil function

BACKGROUND

Neutrophils play a crucial role in the antibacterial host defence system. Edaravone is used in critically ill patients who are often immuno-compromised secondary to concomitant disease or immunosuppressive therapy. The aim of the current study was to assess the effect of edaravone, a novel free-radical scavenger, on several aspects of human neutrophil function using an in vitro system.

METHODS

Chemotaxis, phagocytosis, reactive oxygen species (ROS) production by neutrophil (cellular) and xanthine-xanthine oxidase (acellular) systems, and intracellular calcium ion levels ([Ca(2 +) ]i) were measured in the absence and in the presence (at a clinically relevant concentration, and 0.1-fold, and 10-fold this concentration) of edaravone.

RESULTS

The clinically relevant concentration of edaravone did not inhibit chemotxais, phagocytosis, or superoxide production of neutrophils. Even at its ordinary clinical plasma concentration, the drug inhibited hydrogen peroxide (H(2)O(2)) and hydroxyl radical (OH*) generation in the cellular (neutrophil) as well as in the cell-free (xanthine-xanthine oxidase) system (P < 0.05). Edaravone did not affect elevation of [Ca(2 +) ]i in neutrophils stimulated by a chemotactic factor.

CONCLUSIONS

These findings suggest that edaravone quenched H(2)O(2), and OH* generated rather than impaired the ability of neutrophils to produce the ROS. However, further studies using in vivo systems are required to elucidate the effects of edaravone on neutrophil function in clinical settings.

The use of endoscopic ultrasound-guided fine-needle aspiration for investigation of submucosal and extrinsic masses of the colon and rectum

BACKGROUND AND STUDY AIM

Ensdoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) has been reported as a useful technique for histological diagnosis of submucosal or extrinsic gastrointestinal and pancreatic lesions. The aim of this study was to evaluate the use of EUS-FNA for the diagnosis of lesions either within or adjacent to the wall of the colon and rectum.

PATIENTS AND METHODS

A total of 22 patients with a lesion within the wall of, or adjacent to, the colon or rectum underwent EUS-FNA. They were divided into two groups: patients who had previously had a malignancy (the "previous +ve" group, n = 11), and patients who had not previously had a malignancy (the "previous -ve" group, n = 11). In the four patients who had lesions located proximal to the sigmoid colon, EUS-FNA was performed using a guide wire and overtube. The success rates for adequate tissue sampling and for detecting malignant and benign masses by EUS-FNA were evaluated and the success rate for detection was compared with the success rate of EUS and computed tomography.

RESULTS

Sufficient tissue for evaluation was obtained from 21 of the 22 patients (95.5 %). The overall rate of detection of malignant and benign masses was 95.5 % (21/22) for EUS-FNA and 81.8 % (18/22) for pre-EUS-FNA imaging investigations. Of the 11 patients in the previous +ve group, ten were diagnosed with recurrences of primary malignancies; of the 11 patients in the previous -ve group, four were diagnosed with primary malignancies and seven were diagnosed with benign lesions. There were no complications related to the EUS-FNA procedure.

CONCLUSIONS

EUS-FNA is a safe technique which is useful in the planning of treatment for patients who have a mass within the wall or adjacent to the wall of the entire length of the colon or rectum.

Topical application of the immunosuppressant tacrolimus accelerates carcinogenesis in mouse skin

BACKGROUND

Tacrolimus, produced by the fungus Streptomyces tsukabaensis, is a potent macrolide immunosuppressant widely used in liver and kidney transplantation. Topical tacrolimus has recently been found to be an effective treatment for atopic dermatitis (AD).

OBJECTIVES

Because of the well-known association between T-cell immunosuppression and an increased risk of carcinogenesis, we investigated the effect of topical tacrolimus on skin carcinogenesis in 117 mice.

METHODS

Approximately 8 cm2 of the shaved dorsal skin of 7-week-old female CD-1 mice was treated with 7,12-dimethylbenz[alpha]anthracene (DMBA) dissolved in acetone, which is in general use as a tumour initiator, or acetone alone, on day 1 of the experiment, followed by promoting treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) with or without tacrolimus, or acetone with or without tacrolimus, for 20 weeks. The mice were divided into six treatment groups: (1) DMBA followed by acetone; (2) DMBA followed by TPA; (3) DMBA followed by acetone + tacrolimus; (4) DMBA followed by TPA + tacrolimus; (5) acetone followed by acetone + tacrolimus; and (6) acetone followed by acetone (control).

RESULTS

The induction of skin tumours was significantly greater in the TPA-treated groups than in the absence of TPA. However, after 14 weeks there was marked synergy between tacrolimus and the DMBA/TPA regimen, with 0.47 +/- 0.13 (mean +/- SD) new tumours per mouse per week in group 4 vs. 0.10 +/- 0.025 in group 2 (P < 0.01), and 0.01 +/- 0.002 in group 3. A significant reduction in the CD4/CD8 ratio was found in axillary and inguinal lymph nodes in tacrolimus-treated mice, supporting the presumption that the immunosuppressive effect of the drug was responsible for its effect in promoting tumorigenesis. The major increase in tumours caused by topical tacrolimus was of papillomas, not squamous cell carcinomas. Papillomas are uncommon in humans, and are benign. However, 8.5% of the tumours found in the experiment were squamous cell carcinomas, and a considerable synergy between topical tacrolimus and conventional carcinogens was observed, raising the spectre of some risk of skin carcinogenesis in AD patients undergoing prolonged treatment with tacrolimus.

CONCLUSIONS

Caution and careful surveillance are required with regard to skin lesions in patients treated with tacrolimus for prolonged periods.

Pilot study of pancreatoscopic lithotripsy using a 5-fr instrument: selected patients may benefit

BACKGROUND AND STUDY AIMS

Despite advances in endoscopic procedures and extracorporeal shock wave lithotripsy (ESWL), the removal of impacted pancreatic duct stones demands a certain amount of time. The aim of this study was to determine which patient group might suitable for our single-session treatment.

PATIENTS AND METHODS

The study included 17 patients who were symptomatic due to relapsing pancreatitis with pancreatic duct stones. A 5-Fr miniscope was inserted via the papilla to the impacted pancreatic duct stone and pancreatoscopic laser lithotripsy (PSLL) was performed, under direct vision, in only one session. If complete extraction of the pancreatic duct stones was not achieved with PSLL, ESWL was adopted in subsequent sessions.

RESULTS

Complete extraction of the pancreatic duct stones using PSLL in a single session was achieved in eight of 17 patients. Single-session PSLL was only suitable for patients with pancreatic duct stones smaller than 17 mm in diameter and with no severe stricture or sharp bend in the pancreatic duct proximal to the stones.

CONCLUSIONS

Our single-session endoscopic treatment of pancreatic duct stones was useful in a selected patient group.

Usefulness of magnifying endoscopy in the diagnosis of early gastric cancer

BACKGROUND AND STUDY AIMS

We investigated the characteristic findings of early gastric cancer revealed by magnifying endoscopy, and clarified their relationship with histopathological features.

PATIENTS AND METHODS

A total of 74 patients with early gastric cancer underwent magnifying endoscopy ( x 80) between March 2000 and December 2001. The endoscopic findings demonstrated 11 elevated-type carcinomas and 63 depressed-type, and histological examination showed 56 differentiated carcinomas and 18 undifferentiated carcinomas. The histopathological results were compared with findings from magnifying endoscopy regarding minute surface structure and microvessels.

RESULTS

We were able to roughly classify the minute surface structure of early gastric cancer as shown by magnifying endoscopy into three patterns, as follows: (i). a small regular pattern of sulci and ridges; (ii). an irregular pattern of sulci and ridges; and (iii). a lack of visible structure. Abnormal microvessels observed in cancerous lesions were classified according to two patterns: irregular minute vessels and variation of vessel caliber. The small regular pattern of sulci and ridges was significantly more frequently observed in differentiated carcinoma (30/56, 53.6 %) than in undifferentiated carcinoma (2/18, 11.1 %). Lack of visible structure and irregular minute vessels were significantly more frequently observed in undifferentiated carcinoma (44.4 % and 77.7 %) than in differentiated carcinomas (5.4 % and 51.8 %).

CONCLUSION

The minute surface structure and microvessels observed by magnifying endoscopy were related to histopathological findings. Magnifying endoscopy is valuable for predicting the histological nature in the diagnosis of early gastric cancer.

Protein oxidative damage in the stratum corneum: Evidence for a link between environmental oxidants and the changing prevalence and nature of atopic dermatitis in Japan

BACKGROUND

The incidence of atopic dermatitis (AD) has increased in Japan, along with the number of patients with severe and treatment-resistant AD in urban and industrial areas. We hypothesize that these changes could be due to increased reactive oxygen species (ROS) generated from environmental pollution and solar radiation.

OBJECTIVES

To demonstrate whether direct oxidative protein damage of the stratum corneum of the biopsied skin from AD patients is increased when compared with controls.

PATIENTS AND METHODS

Carbonyl moieties in skin biopsies from 75 patients with AD were assessed using both spectrophotometric and immunohistochemical detection of the formation of dinitrophenylhydrazone (DNP) from dinitrophenylhydrazine (DNPH). These were compared with diseased and normal controls. Lipid peroxidation was also assessed by staining with antibody to 4-hydroxy-2-nonenal (4-HNE), an aldehyde product of oxidized omega-6-fatty acids. In addition, the activity of superoxide dismutase (SOD), an effective scavenger of ROS, was assessed and compared with controls.

RESULTS

The level of protein carbonyl moieties in patients' skin was elevated and correlated directly with the severity of the disease. In contrast, DNP formation was not significantly increased in diseased controls, when compared with healthy volunteers, and no statistical significance was found between the two control groups. SOD activity was increased except for those with extra-severe disease. Positive staining with anti-DNP antibody and anti-4-HNE antibody were found in the most superficial layers of the stratum corneum.

CONCLUSIONS

This study has found an association between AD severity and markers of ROS-associated damage, adding weight to the hypothesis that environmentally generated ROS may induce oxidative protein damage in the stratum corneum, leading to the disruption of barrier function and exacerbation of AD.

Associations between tumor diameter and prognostic variables of epithelial ovarian cancer

PURPOSE

Associations of tumor diameter in epithelial ovarian cancer with clinical and pathological prognostic variables were investigated.

METHODS

The clinical and pathological records of 233 patients diagnosed with epithelial ovarian cancer and treated at Aichi Cancer Center were studied.

RESULTS

Tumor diameters of 44 patients (18.9%) were < 5 cm, 90 (38.6%) were 5-10 cm, and 99 (42.5%) were > 10 cm. While 90.9% (40/44) of < 5 cm tumors presented with FIGO stage III-IV, 40.4% (40/99) of > 10 cm tumors were advanced. Intra-abdominal disease was also significantly associated with tumor diameter, although differences among lymph-node status were not significant. The incidence of serous and endometrioid adenocarcinoma in < 5 cm tumors were 75.0% (33/44) and 11.4% (5/44), respectively, while those of > 10 cm tumor were 32.3% (32/99) and 17.2% (17/99). Multivariate analysis revealed that tumor diameter was not an independent prognostic variable.

CONCLUSION

Tumor diameter of ovarian cancer is associated closely with histological subtypes and stage of disease, especially intra-abdominal disease.

Effects of ropivacaine on human neutrophil function: comparison with bupivacaine and lidocaine

BACKGROUND AND OBJECTIVE

Neutrophils are important both for the immunological defence system and for the inflammatory tissue autoinjury mechanism. However, many local anaesthetics impair certain neutrophil functions. The aim was to assess the effects of ropivacaine, bupivacaine and lidocaine on human neutrophils from adult volunteers.

METHODS

Chemotaxis, phagocytosis, reactive oxygen species production, intracellular calcium ion ([Ca2+]i) concentrations and protein kinase C activity were measured in the absence and presence of ropivacaine, bupivacaine or lidocaine. The lowest concentrations of the local anaesthetics were similar to those clinically observed in the plasma.

RESULTS

Bupivacaine did not affect any neutrophil function (P > 0.05). Ropivacaine failed to change chemotaxis or phagocytosis, while lidocaine suppressed both these neutrophil functions. Ropivacaine (15, 150 microg mL(-1)) and lidocaine (20, 200 microg mL(-1)) impaired neutrophil production of O2-, H2O2 and OH- (P < 0.05) at similar rates (by 7-10%). These same concentrations of ropivacaine and lidocaine suppressed [Ca2+1i elevation. Finally, neither ropivacaine nor bupivacaine inhibited protein kinase C activity, while lidocaine did.

CONCLUSIONS

Suppression of the [Ca2+]i response in neutrophils by ropivacaine may represent one of the mechanisms responsible for the impairment of neutrophil functions. It should be emphasized that the inhibitory effects of ropivacaine are minor and are attained only at high concentrations, which may minimize the clinical implication of ropivacaine-associated impairment of reactive oxygen species production. Further studies using in vivo systems are required to identify the inhibitory effects of ropivacaine on reactive oxygen species production in clinical settings.

Simultaneous multiple early cancers of esophagus and stomach treated by endoscopic mucosal resection

Endoscopic mucosal resection (EMR) has been accepted as a completely curative treatment of gastrointestinal mucosal cancers. With advances in diagnostic techniques, the tendency to detect simultaneous multiple primary cancers is increasing. Patients with another cancer coexisting with esophageal cancer have had a poor prognosis, but if both cancers are detected in the early stage, complete treatment consisting only of endoscopic surgery, with a good prognosis, is expected. We describe two cases of simultaneous multiple early cancers of the stomach and esophagus, treated by EMR.

Genomic organization and organ-specific expression of a nuclear gene encoding phage-type RNA polymerase in Nicotiana sylvestris

We have isolated and sequenced a nuclear gene and cDNA encoding bacteriophage T7-type single subunit RNA polymerase, NsRpoT-A, from Nicotiana sylvestris. NsRpoT-A consists of 19 exons and 18 introns; the first intron is 17 kb, the longest yet identified in a plant gene. Genomic Southern analysis indicated that N. sylvestris contains a small family of NsRpoT genes. Quantitative RT-PCR revealed that steady-state mRNA levels are highest in the leaves and lowest in the cotyledons. Phylogenetic analysis of NsRpoT-A and the RpoT proteins of other plant species suggested that NsRpoT-A is a mitochondrial protein. The TargetP program predicted localization of the NsRpoT-A gene product to the mitochondria. Using a transient expression assay and protoplasts from N. sylvestris mesophyll cells, we clearly demonstrated that the N-terminal sequence of NsRpoT-A targets the protein to the mitochondria. We therefore named this protein NsRpoTm.

Effect of palmitic acid on neutrophil functions in vitro

BACKGROUND

It has been shown that in acne comedones the proportion of linoleic acid is markedly decreased, while palmitic acid is significantly increased. We previously reported that the decreased proportion of linoleic acid, which markedly suppresses neutrophil reactive oxygen species (ROS) generation and phagocytosis, contribute to the worsening of acne inflammation. The aim of this study was to examine the effect of palmitic acid on neutrophil functions in vitro.

METHODS

We investigated the effect of palmitic acid on inflammatory parameters such as neutrophil chemotaxis, phagocytosis, and ROS generation. Reactive oxygen species generation in a cell-free, xanthine-xanthine oxidase system was also assessed. The species examined were superoxide radical anion (O2-), hydrogen peroxide (H2O2), and hydroxyl radical (OH.).

RESULTS

Palmitic acid significantly decreased H2O2 generation both by neutrophils and in the xanthine-xanthine oxidase system, while neutrophil chemotaxis and phagocytosis as well as O2- and OH. generation by both systems were not markedly affected in the presence of palmitic acid.

CONCLUSIONS

The present study suggests that palmitic acid may be involved in the pathogenesis of acne inflammation from a standpoint of oxidative tissue injury.

A comparison of atenolol, labetalol, esmolol, and landiolol for altering human neutrophil functions

IMPLICATIONS

Neutrophils play a pivotal role in the antibacterial host defense system. Atenolol, labetalol, esmolol, and landiolol at clinically relevant concentrations failed to change neutrophil functions. Our findings indicate that we may be able to use these beta-antagonists without great caution in clinical settings.

Piecemeal endoscopic aspiration mucosectomy for large superficial intramucosal tumors of the stomach

BACKGROUND AND STUDY AIMS

As endoscopic techniques continue to develop, endoscopic mucosal resection is increasingly being used in the treatment of intramucosal gastric tumors. The aim of this study was to explore the feasibility of piecemeal endoscopic aspiration mucosectomy for large superficial intramucosal tumors of the stomach.

PATIENTS AND METHODS

The study group consisted of five consecutive patients with large superficial intramucosal tumors of the stomach, 4 cm or more in diameter. Piecemeal endoscopic aspiration mucosectomy using a cap-fitted panendoscope was carried out. The initial resection was undertaken at the oral side of the lesion. Subsequent resections were carried out along the anal margin of the previous resection site, until the marks around the boundary of the tumor completely disappeared.

RESULTS

The shape of the tumors was slightly elevated in four cases and slightly depressed in one. The mean diameter of the tumors was 4.8 cm. The diameters of the resected specimens ranged from approximately 1.0 cm to 2.3 cm. The numbers of piecemeal resection procedures needed per lesion ranged from five to 18 (mean 11). The visual field was well ensured by the cap, and the tumors were macroscopically completely resected without any complications in all patients. The final histological diagnoses in the specimens were adenoma in one case and mucosal carcinoma in adenoma in four. One patient had residual or recurrent tumor, and received full treatment with additional endoscopic procedures.

CONCLUSIONS

Piecemeal endoscopic aspiration mucosectomy is a simple and very useful technique for treating large superficial intramucosal tumors of the stomach.

Endothelium-dependent relaxation by cilostazol, a phosphodiesteras III inhibitor, on rat thoracic aorta

The relaxation effect of cilostazol, a phosphodiesterase III inhibitor, on the thoracic aorta was investigated. Cilostazol induced the relaxation of the thoracic aorta precontracted by phenylephrine in a concentration-dependent manner. The concentration-dependent relaxation was shifted to the right in the endothelium denuded aorta compared with that of intact endothelium, suggesting that this relaxation was partly dependent on endothelium. Cilostazol-induced relaxation of thoracic aorta tone was reversed by treatment with N(G)-nitro L-arginine (L-NNA), a competitive inhibitor of nitric oxide (NO) synthase. Cilostazol also significantly increased the NO level in the porcine thoracic aorta. In rats treated with cilostazol, the urinary excretion of nitrites, a stable metabolite of NO, and basal production of NO of the aortic ring were significantly greater than in those without treatment. These findings indicate that cilostazol-induced vasodilation of the rat thoracic aorta was dependent on the endothelium, which released NO from aortic endothelial cells.

Modification of Arg-13 of mu-conotoxin GIIIA with piperidinyl-Arg analogs and their relation to the inhibition of sodium channels

mu-Conotoxin GIIIA, a peptide toxin isolated from the marine snail Conus geographus, preferentially blocks skeletal muscle sodium channels in vertebrates. In this study, analogs of mu-conotoxin GIIIA in which essential Arg-13 was replaced with arginine analogs consisting of a piperidyl framework to regulate length and direction of the side chain were synthesized. Synthesized analogs exhibited similar CD and NMR spectra to that of GIIIA, suggesting a three-dimensional structure identical to that of the native toxin. The biological activities of piperidyl analogs were decreased or lost despite the small change in the side chain of Arg-13. The investigated structure-activity relationships in inhibiting electrically stimulated muscle contraction suggest that the guanidinium group at amino acid position 13 interacts best when spaced with three to four carbons and placed in a vertical direction from the peptide loop. Thus, the position of the guanidinium group at Arg-13 of GIIIA must be located in a certain range for its strong interaction with the channel protein.

Exacerbatory mechanism responsible for water immersion stress-induced gastric lesions in aged rats compared with young rats

1. The present study was designed to investigate whether or not ageing affects the development of water immersion stress-induced gastric lesions in rats. Effects of cetraxate, an anti-ulcer drug, were also examined. 2. Gastric lesions were induced by 6 h water immersion stress in rats. Gastric mucosal blood flow was determined by the hydrogen gas clearance technique and nitric oxide synthase (NOS) activity was measured enzymatically. 3. Early development of gastric lesions was observed in aged rats and exacerbation of gastric lesions was also found. Lowering of gastric mucosal blood flow and reduced NOS activity were observed in aged rats. 4. Cetraxate mitigated the development of gastric lesions in young rats and also increased gastric mucosal blood flow and NOS activity. However, these favourable effects were diminished in aged rats. 5. Decreased NOS activity may be an important exacerbatory factor to the development of gastric lesions in aged rats. 6. Effects of cetraxate differed between young rats and aged rats. 7. These results may explain the refractoriness and drug resistance in gastric ulcers encountered by elderly individuals.

Involvement of adenosine in vascular contractile preconditioning

Measurements of isometric tensions of rat aortic rings revealed the fact that when aortic rings with intact endothelium were precontracted (preconditioned) for 20 min by the alpha1-adrenergic agonist phenylephrine (10 microM), the tonic level of subsequent contraction by the same agonist was depressed and/or declined regardless of the presence or absence of endothelium during the second contraction. The removal of endothelium before preconditioning showed no such phenomenon. With the use of specific blockers, involvements of adenosine or of ATP-sensitive K+ (K(ATP)) channels during preconditioning or second contraction, respectively, were evaluated. Actions of nitric oxide synthase, cyclooxygenase, P(2) ATP purinoceptors, or K(ATP) channels during preconditioning appear not to be involved. Exogenous adenosine (up to 100 microM) without endothelium could mimic the preconditioning; however, contractile preconditioning by phenylephrine, mechanical stretching, or activation of protein kinase C needed to be done. The release of adenosine and adenine nucleotides from aortic rings was augmented by phenylephrine or by mechanical stretching of the rings with intact endothelium. Our results suggest that during vasocontraction, endothelium-derived adenosine acquires an ability to protect vascular tone against subsequent repeated contractions by mediating a delayed, possibly indirect, opening of K(ATP) channels.

The nutritional status of elderly bed-ridden patients receiving tube feeding

Long-term enteral feeding by tube has become a frequently used procedure in elderly patients. However, only a few studies dealing with the nutritional assessment of such patients are currently available. This study was designed to clarify this issue. Anthropometric and biochemical variables, energy expenditure and dietary intake were investigated in 44 hospitalized bed-ridden patients with and without tube feeding over 65 years of age and 41 age-matched free-eating elders in a nursing home. All patients with tube feeding received enteral nutrition by nasogastric tube. The body weight, body mass index, mid-upper-arm circumference, arm muscle circumference and serum level of albumin were significantly lower in the patients with and without tube feeding, compared with free-eating elders of both genders (p<0.05). Energy intakes of the patients with tube feeding were 1,171+/-286 kcal/d (about 26 kcal/kg/d), which is comparable to the predicted total energy expenditure (1.2 x basal energy expenditure). Protein intake was 44.9+/-13.1 g/d (about 1.0 g/kg/d) and the percentage of protein per total energy was 15%. These intakes are generally considered to be optimal for bed-ridden patients receiving tube feeding. However, the incidence of protein-malnutrition, as evidenced by decreased arm muscle circumference (<80% of normal) and hypoalbuminemia (<35 g/L), in the patients with tube feeding was significantly higher than that in the healthy elders. In addition, the orally fed bed-ridden patients were also malnourished, suggesting that the bed-ridden patients easily became malnourished even if they were fed energy and protein which approximated calculated predicted values. These findings raise a problem concerning nutritional management of bed-ridden patients.

K(Ca) channel-opening activity of Ginkgo Biloba extracts and ginsenosides in cultured endothelial cells

1. Extracts of Ginkgo biloba (EGb) and ginsenosides (GS) have been reported to induce vasorelaxation. In the present study, the role of K+ channels in the action of EGb and GS to activate nitric oxide synthase (NOS) activity was investigated in cultured endothelial cells. 2. Nitric oxide synthase activity of cultured endothelial cells detected by the reduced nicotinamide adenine dinucleotide phosphate (NADPH) histochemistry method was significantly increased after treatment with 20 microg/mL EGb or 40 microg/mL GS plus 10 mmol/L L-arginine. The effect was completely abolished by the addition of 0.5 micromol/L Nomega-nitro-L-arginine, an inhibitor of NOS, to the incubation medium and partially inhibited by 10 micromol/L tetraethylammonium (TEA), an inhibitor of Ca2+-activated K+ (KCa) channels. 3. Application of EGb to the intracellular surface of excised inside-out patches activated K+ channels in a concentration-dependent manner in the concentration range 1-100 microg/mL. Channel activity was also activated by application of GS at concentrations ranging from 1 to 300 microg/mL. The modulation of channel activity was inhibited by 0.5 mmol/L TEA but not by 0.5 mmol/L glibenclamide, an inhibitor of ATP-sensitive K+ channels. 4. Thus, in cultured endothelial cells, the increase in NOS activity induced by EGb or GS depends on the activity of KCa channels. These compounds may regulate nitric oxide release by changing the cell membrane potential in vascular endothelial cells.