Vitamin C reduces ischemia-reperfusion injury in a rat epigastric island skin flap model

Free radicals have been implicated in the cause of ischemia-reperfusion injury. Various agents have been used in an attempt to reduce ischemia-reperfusion injury pharmacologically, including free radical scavengers. Vitamin C (ascorbic acid), a well-known free radical scavenger, has not, to the best of our knowledge, been evaluated in this respect. Previous work at our institution has shown that vitamin C decreases capillary permeability, thus significantly reducing fluid resuscitation requirements in postburn cases. Because this is due in part to the scavenging effect of vitamin C on free radicals, we investigated the role, if any, of vitamin C on ischemia-reperfusion injury in a rat epigastric island skin flap model. Twenty-four adult Sprague-Dawley rats were divided into control and vitamin C groups. Superficial epigastric island skin flaps measuring 6.0 x 3.5 cm were raised. Pedicles were isolated and occluded with microvascular clamps for 6 hours. The flaps were then sutured back to their beds over Steri-Drape barriers. Fifteen minutes before reperfusion, the control group flaps were perfused via femoral artery cannulation with normal saline (2.5 ml/kg). The vitamin C-treated group was perfused in a similar fashion with 2.5 ml/kg of a vitamin C/normal saline solution (27 mg/ml). The animals were observed for 7 days, and the percentage of flap survival was determined using a paper template technique. The vitamin C-treated group demonstrated a significantly higher percentage of flap survival than did the control group (25.8% mean vs. 7.5% mean, p < 0.025). In this animal model, vitamin C reduced or limited reperfusion injury after 6 hours of ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

[A case of pneumonitis induced by PL granules]

We report a case of pneumonitis induced by PL granules. A 45-year-old man took PL granules and other drugs for fever and headache. Because he subsequently developed high grade fever, cough and diarrhea, he was admitted to our hospital. His chest X-ray film revealed multiple patchy shadows in both lung fields. Analysis of bronchoalveolar lavage fluid (BALF) disclosed a high number of cells (total), lymphocytes, and a high CD4/CD8 ratio. Microscopic examination of transbronchial lung biopsy (TBLB) specimens showed infiltration of mononuclear cells and thickening of the alveolar wall. After discontinuation of drugs, his condition (symptoms, laboratory data, and chest X-ray findings) promptly improved. Lymphocyte stimulation tests (LST) for PL granules and acetaminophen were positive and an oral challenge test with PL granules was also positive. Based on these findings, we diagnosed this as a case of pneumonitis and enteritis due to PL granules. To our knowledge, this is the first reported case of pneumonitis due to PL granules.

Effect of muscarinic receptor modulators in the hypothalamic supraoptic nucleus of the rat

Muscarinic antagonists were injected into the hypothalamic supraoptic nucleus (SON) and their effects on the acetylcholine (ACh) release of this nucleus were studied by in vivo microdialysis techniques. Atropine, AF-DX116 (a M2-receptor antagonist), 4-DAMP (a M3-receptor antagonist) and pirenzepine (a M1-receptor antagonist) concentration-dependently increased the ACh release. The EC50 values for these antagonists were 15 nM for atropine, 7.8 microM for pirenzepine, 0.39 microM for AF-DX116 and 59 nM for 4-DAMP, suggesting the autoregulation of the ACh release through an activation of M2 and M3 subtypes of muscarinic receptors in the SON. The postsynaptic effect of muscarinic receptors on urine outflow was studied by microinjection of selective muscarinic receptor agonists and antagonists into the SON. McN-A-343 (a M1-receptor agonist) had no significant effect on urine outflow. Pre-microinjection of atropine, 4-DAMP, p-F-HHSiD (a M3-receptor antagonist) or pirenzepine into the SON concentration-dependently attenuated the oxotremorine-induced antidiuresis. In contrast, AF-DX116 and methoctramine had no effect on this oxotremorine-induced action. These results suggest that the M3-subtype may contribute to the antidiuretic actions. Nicotine produced an increase in ACh release in the SON and also induced potent antidiuretic effects, both of which were inhibited by hexamethonium. Thus, in the SON, the ACh release may be autoregulated by M2- and M3-subtypes of muscarinic receptors and the antidiuretic effects of ACh produced through an activation of the M3-subtype.

Antidiuretic effects of ATP induced by microinjection into the hypothalamic supraoptic nucleus in water-loaded and ethanol-anesthetized rats

The effects of microinjection of purinoceptor agonists into the hypothalamic supraoptic nucleus (SON) on urination were examined in water-loaded and ethanol-anesthetized rats. Adenosine triphosphate (ATP), but neither adenosine diphosphate (ADP), adenosine monophosphate (AMP) nor adenosine, concentration-dependently decreased the urine outflow with concomitant increase in the urine osmotic pressure. The ED50 value for ATP was approx. 60 nmol. The antidiuretic effect of ATP was blocked either by prior injection of theophylline (an antagonist of the P1-type purinoceptor) or by intravenous administration d(CH2)5-D-Tyr(Et)-valine-arginine-vasopressin (VAVP). These results suggest that ATP injected into the SON has antidiuretic effects due to release of AVP through an activation of theophylline-sensitive purinoceptors.

Cultured rat astrocytes possess Na(+)-Ca2+ exchanger

Na(+)-Ca2+ exchange activity in its reverse mode was demonstrated in cultured rat astrocytes. Combination of ouabain (1 mM) and monensin (20 microM) caused a marked increase in 45Ca2+ uptake in astrocytes. 45Ca2+ uptake was also stimulated by lowering the external Na+ concentration. Ouabain plus monensin-stimulated 45Ca2+ uptake was blocked by 3,4-dichlorobenzamil (IC50, 16 microM), an inhibitor of Na(+)-Ca2+ exchanger, but not by nifedipine (0.1 microM). The stimulated-45Ca2+ uptake was observed even in K(+)-free medium, and external K+ at 5-10 mM caused a 2.2-fold increase in the uptake. Microspectrofluorimetry using the Ca(2+)-sensitive dye fura-2 showed that ouabain plus monensin increased intracellular Ca2+ concentration in single astrocytes. The Ca2+ signal was dependent on external Ca2+ (EC50, 1.4 mM), and blocked by 20 microM 3,4-dichlorobenzamil, but not by Ca2+ channel blockers (Cd2+, 20 microM; Ni2+, 100 microM). Antiserum of cardiac Na(+)-Ca2+ exchanger recognized 160 and 120-135 kDa proteins on SDS-polyacrylamide gel electrophoresis of astrocyte homogenate. Northern blot analysis revealed the presence of mRNA for the exchanger protein in astrocytes. These findings indicate that Na(+)-Ca2+ exchanger which is modulated by K+ is present in cultured rat astrocytes.

Peripheral neuroectodermal tumor presenting pleural effusion

Pleural effusion is a common finding of peripheral neuroectodermal tumor (PNET) of the chest wall (Askin's tumor), but little is known about the characteristics. A case of Askin's tumor with pleural effusion is reported. Repeated cytologies were negative for malignancy, but levels of lactic dehydrogenase (LDH) and neuron-specific enolase (NSE) in the pleural effusion were increased. Surgical biopsy was performed and immunohistochemical study of the tumor revealed the diagnosis.

Dose-dependent inhibition of glutathione S-transferase placental form-positive hepatocellular foci induction in the rat by methyl propyl disulfide and propylene sulfide from garlic and onions

Two organosulfur compounds, methyl propyl disulfide (MPD) and propylene sulfide (PS) from garlic and onions, were studied for their modifying effects on hepatocarcinogenesis in the F344 rats. Modifying potential was scored by comparing the number and area per cm2 of induced glutathione S-transferase placental form (GST-P)-positive foci in the liver. MPD and PS significantly reduced both these parameters of GST-P-positive foci in a dose-dependent manner. To investigate possible mechanisms of inhibition, ornithine decarboxylase (ODC) and spermidine/spermine N1-acetyltransferase (SAT) activities were measured. In MPD and PS-high dose-treated liver tissue there was a tendency for their decrease, albeit non-significant, which suggested that the inhibitory effect might have been caused by decreased cell proliferation associated with decreased polyamine biosynthesis. In evaluating relationships between diet and cancer, it is thus necessary to consider various effects in assessing possible protective roles of garlic and onions.

In vitro reconstruction of hybrid arterial media with molecular and cellular orientations

A hybrid medial tissue composed of a type I collagen gel, into which smooth muscle cells (SMCs) derived from bovine aortic media were 3-dimensionally (3D) embedded, was constructed around an elastomeric silicone tube (outer diameter: 8 mm). Subsequently, hybrid tissues thus prepared were subjected to three modes of mechanical stimulation in the medium: one was subjected to flotation with no disturbance (isotonic control), the second was kept isometrically (static stress) and the third was subjected to continuous periodic stretch by inflation of the embedded silicone tube which stimulated arterial pulsation (dynamic stress, amplitude: 5% in inner diameter; frequency: 60 RPM). After a 5-day culture period, hybrid tissues were morphologically investigated. In control gels, polygonal SMCs and extracellular collagen fiber bundles were randomly oriented. On the other hand, upon static or dynamic stress loading, bipolar spindle-shaped SMCs and dense collagen fiber bundles were aligned circumferentially around the silicone tube, which proceeded with time. The orientations of SMCs and collagen fibers were more prominent in dynamically stressed hybrid tissues than those in statistically stressed ones. The pulsatile stress-loaded hybrid medial tissue mimicked the media of native muscular arteries in terms of cellular and molecular orientations.

Mechanical stress-induced orientation and ultrastructural change of smooth muscle cells cultured in three-dimensional collagen lattices

The effect of tensile stress on the orientation and phenotype of arterial smooth muscle cells (SMCs) cultured in three-dimensional (3D) type I collagen gels was morphologically investigated. Ring-shaped hybrid tissues were prepared by thermal gelation of a cold mixed solution of type I collagen and SMCs derived from bovine aorta. The tissues were subjected to three different modes of tensile stress. They were floated (isotonic control), stretched isometrically (static stress) and periodically stretched and recoiled by 5% above and below the resting tissue length at 60 RPM frequency (dynamic stress). After incubation for up to four wk, the tissues were investigated under a light microscope (LM) and a transmission electron microscope (TEM). Hematoxylin and eosin-stained LM samples revealed that, irrespective of static or dynamic stress loading, SMCs in stress-loaded tissues exhibited elongated bipolar spindle shape and were regularly oriented parallel to the direction of the strain, whereas those in isotonic control tissues were polygonal or spherical and had no preferential orientation. In Azan-stained samples, collagen fiber bundles in isotonic control tissues were somewhat retracted around the polygonal SMCs to form a random network. On the other hand, those in statically and dynamically stressed tissues were accumulated and prominently oriented parallel to the stretch direction. Ultrastructural investigation using a TEM showed that SMCs in control and statically stressed tissues were almost totally filled with synthetic organelles such as rough endoplasmic reticulums, free ribosomes, Golgi complexes and mitochondria, indicating that the cells remained in the synthetic phenotype. On the other hand, SMCs in dynamically stressed tissues had increased fractions of contractile apparatus, such as myofilaments, dense bodies and extracellular filamentous materials equivalent to basement membranes, that progressed with incubation time. These results indicate that periodic stretch, in concert with 3-D extracellular collagen matrices, play a significant role in the phenotypic modulation of SMCs from the synthetic to the contractile state, as well as cellular and biomolecular orientation.

Effect of proton pump inhibitor on cell growth and sensitivity to cis-diamminedichloroplatinum(II) in non-small cell lung cancer cell lines

Recently, the importance of the potassium pump in the cellular accumulation of cis-diamminedichloroplatinum(II) (CDDP) has been reported. In this study we evaluated the role of the proton pump as a determinant of the sensitivity to CDDP in non-small cell lung cancer cell lines in vitro by using a selective proton pump inhibitor, AG-2000. PC-9 and PC-9/CDDP cell lines, which are sensitive or resistant to CDDP, were used for these experiments. PC-9/CDDP was 17.4-fold more resistant to CDDP than PC-9 cells. Relative resistance was not altered by co-incubation with a non-cytotoxic dosage of AG-2000. From these studies, it was shown that the proton pump inhibitor AG-2000 did not enhance the sensitivity to CDDP. However, as AG-2000 is not cytotoxic and does not compromise the CDDP-sensitivity in NSCLC cells at the concentration of clinical use for gastroduodenal ulcer, AG-2000 can be used with CDDP in chemotherapy for lung cancer.

Induction of multinucleated giant cells from rheumatoid arthritis (RA) synovial adherent cells by anti-DR antibody

To determine the effects of signalling through the DR molecule on synoviocytes from RA patients, the synovial adherent cells were incubated with anti-DR antibodies. After 24 h incubation, we found the formation of multinucleated giant cells in that culture. These multinucleated giant cells showed characteristics of monocyte-macrophage lineage cells and precursor of osteoclasts. Cyclohexamide inhibited the formation of multinucleated giant cells, but not the aggregation of synovial cells, suggesting that newly synthesized proteins are associated with the cell fusion. These results revealed a new mechanism in multinucleated giant cell formation.

Symptomatic Chiari malformation and associated pathophysiology in pediatric and adult patients without myelodysplasia

The clinical characteristics of eight pediatric and five adult patients with Chiari malformation were evaluated. Six pediatric and five adult patients had associated syringomyelia. All patients initially underwent a suboccipital craniectomy with upper cervical (C-1 and/or C-2) laminectomy and duraplasty, and/or shunting procedures. The clinical characteristics of the pediatric and adult groups were compared. The mean interval between onset of symptoms and operation was shorter in the pediatric group (3 yrs 6 mos) than in the adult group (7 yrs 1 mo). Pediatric patients without syringomyelia had the shortest mean interval of 1 year 8 months. Preoperatively, the clinical features were more severe in the adult patients than in the pediatric patients. Postoperatively, seven of eight pediatric patients improved and one stabilized, while two of five adult patients improved, one stabilized, and in two the disease continued to progress despite multiple corrective procedures. Cine magnetic resonance imaging revealed correction of the abnormal cerebrospinal fluid (CSF) flow at the craniovertebral junction and decreased to-and-fro movement in the syrinx after posterior fossa decompression, which were closely correlated with the improvement of clinical features in pediatric patients. However, adult patients required further procedures because of the multifactorial nature of the disease. Evaluation of abnormal CSF pathways at the craniovertebral junction is important for investigating the pathogenesis of Chiari malformation and associated syringomyelia.

DT-diaphorase as a determinant of sensitivity to adriamycin in non-small-cell lung-cancer cell lines

We have reported the establishment of a mitomycin-C (MMC)-resistant non-small-cell lung-cancer cell line, PC-9/MC4. As determined by an MTT assay, this resistant cell line was found to be 4 times more sensitive to adriamycin (ADM) than was the parental PC-9. There were no significant differences in sensitivity to etoposide, mitoxantrone, daunomycin, epirubicin, pirarubicin, 9-aminoanthracycline or 3'-deamino-3'-morpholino-13-deoxo-10-hydroxy carminomycin. These data suggest that neither qualitative or quantitative changes in DNA topoisomerase II nor the enhanced repair of DNA can explain the differing sensitivity to ADM observed. No significant differences were found in the accumulation of ADM and glutathione (GSH) in these cell lines. Although total glutathione-S-transferase (GST) activity in PC-9/MC4 cells was lower than that observed in PC-9 cells and treatment with ethacrynic acid (EA) reduced sensitivity to ADM in both cell lines, relative resistance was unaffected. NADH-cytochrome b5 reductase (B5R) activity in PC-9/MC4 cells showed a 3-fold greater decrease than that in PC-9 cells, and DT-diaphorase (DTD) activity in PC-9/MC4 cells showed an approximately 200-fold greater decrease than that in PC-9 cells. Addition of dicumarol, an inhibitor of DTD, decreased the sensitivity of ADM of PC-9 but not of PC-9/MC4. DTD activity in the PC-9 cell line was inhibited by treatment with dicumarol while in PC-9/MC4 it remained unchanged. These data suggest that DT-diaphorase is a determinant of sensitivity to ADM in the 2 cell lines.

[Chyluria treated with inguinal lymphangiovenous and lymph node-venous anastomosis: a case report]

Stripping and ligation of the renal lymphatics has been a standard operation for patients with chyluria in Japan. However, recently, inguinal lymph node-saphenous vein anastomosis and lymphangiovenous anastomosis in the spermatic cord or the lower limb are introduced as a microsurgical treatment of chyluria with good result from China. We present a case of 50-year-old female with chyluria, which was cured by the lymphatic-venous anastomosis at the groin. The patient had lived in Okinawa, an area of endemic filariasis, till 23 years of age. She noted chyluria for the first time at 28 years of age, when it was treated by irrigation of the renal pelvis with silver nitrate solution. The symptom recurred at 48 years of age, and fatigue developed two months before admission. The conservative treatments including rest, low fat diet and repeated irrigation of the renal pelvis were carried out, but these were ineffective. Therefore, bilateral inguinal lymph node-saphenous vein anastomosis and lymphangiovenous anastomosis in the same wound on the right were performed. The chyluria disappeared five months after the operation. The lymphatic-venous anastomosis at the superficial part of the body may be the surgical procedure of choice, because they are effective, simple, less invasive and less traumatic.

[Persistent müllerian duct syndrome: report of two cases]

Persistent Mullerian duct syndrome is characterized by the retention of mullerian derivatives in patients otherwise normally virilized. Clinically, the persistence of uterus and tubes leads either to cryptorchidism or inguinal hernia. The condition is usually discovered at surgery. We report two boys with this anomaly. In each case, hysterectomy and orchidopexy were carried out. The gonads were testes and the karyotype was 46, XY. Long-term follow up for these patients is necessary because of an increased risk of testicular tumors and infertility which will develop in future.

Microinjections of angiotensin II into the supraoptic and paraventricular nuclei produce potent antidiureses by vasopressin release mediated through adrenergic and angiotensin receptors

We investigated the effects of angiotensin II (Ang II), microinjected into the supraoptic (SON) and paraventricular (PVN) nuclei of rats, on the urine outflow rate and underlying mechanisms. Ang II produced antidiuretic effects in a dose-dependent manner with ED50 values of 0.1 and 0.05 nmol in the SON and PVN, respectively. [Sar1, Ile8]Ang II at 0.1 nmol diminished the Ang II (0.5 nmol)-induced antidiureses in the SON more markedly than in the PVN. A high dose of [Sar1,Ile8]Ang II, 1 nmol, completely inhibited the effects in both the nuclei. In addition, the Ang II (1 nmol)-induced antidiuretic effects were partially inhibited by phenoxybenzamine (80 nmol) in the SON and by phenoxybenzamine, timolol (100 nmol) and propranolol (100 nmol) in the PVN. The microinjection of Ang II (1 nmol) into both the nuclei, after pretreatment with a vasopressin V1V2-antagonist, d(CH2)5-D-Tyr(Et)VAVP (i.v.) significantly increased the urine outflow rate. These findings suggest that 1) Two mechanisms account for the Ang II receptor-mediated antidiureses resulting from an increase in vasopressin release: direct stimulation on vasopressin-containing neurons and indirect stimulation on them through alpha-adrenoceptors in the SON and alpha- and beta-adrenoceptors in the PVN; 2) The Ang II-induced antidiuretic effect in the SON is slightly less potent than that in the PVN; and 3) Ang II receptors in the nuclei may possibly produce the diureses through mechanisms that are not presently understood.

[A case of prostatic adenocarcinoma with pulmonary metastases--diagnosis by transbronchial lung biopsy and immunohistochemistry]

Metastatic pulmonary adenocarcinoma was found in a 79-year-old man, who had symptoms of general malaise and poor appetite. An extensive work-up including a transurethral resection of the prostate, failed to establish the primary site of the malignancy. By administering chlormadinone acetate for prostatic hypertrophy, the pulmonary metastases improved dramatically. The tumor cells in the lung, which had previously been obtained by transbronchial lung biopsy, stained positive for prostatic acid phosphatase and prostatic specific antigen. These data suggested that prostatic carcinoma had metastasized to the lung. The prostatic carcinoma was finally confirmed at autopsy.

Study of the balance between coagulation and fibrinolysis in disseminated intravascular coagulation using molecular markers

Plasma levels of thrombin-antithrombin III complex (TAT), plasmin-alpha 2-plasmin inhibitor complex (PIC) and active plasminogen activator inhibitor (PAI) were assayed in 66 cases of disseminated intravascular coagulation (DIC). Significant elevation of both TAT and PIC was observed in all cases of DIC. Most elevated levels of TAT were seen in DIC with acute promyelocytic leukaemia (APL) and sepsis. The highest levels of PIC were seen in DIC with APL but were much lower in sepsis. A significant elevation in active PAI was observed in DIC due to acute leukaemia (apart from APL), chronic myeloid leukaemia and sepsis, but not in APL, non-Hodgkin lymphoma and cancer. Active PAI was higher in patients with multiple organ failure (MOF) than in those without MOF while PIC was lower in patients with this complication. Thus, the balance of coagulation and fibrinolysis varied according to the underlying cause of DIC; APL had more dominant activation of fibrinolysis, while sepsis had greater activation of coagulation. It is suggested that the inhibition of secondary fibrinolytic activation plays an important role in the progression of MOF by the disturbance of the microcirculation.

Vasodilating actions of cromakalim in resting and contracting states of carotid arteries from spontaneously hypertensive rats

To determine the properties of cromakalim-opened K+ channels in arterial smooth muscle of spontaneously hypertensive rats (SHR), the effects of cromakalim on tension and 86Rb efflux were compared in endothelium-denuded strips of carotid arteries from 13-week-old SHR and normotensive Wistar-Kyoto rats (WKY). The addition of cromakalim or of nifedipine to resting strips caused a relaxation only in SHR. When strips from both strains were contracted with 15.9 mM K+, the magnitude of the precontraction was greater in SHR than in WKY. Under these conditions, relaxant responses to lower concentrations of cromakalim were decreased and those to higher concentrations of cromakalim were increased in SHR. When strips from both strains were contracted with a different concentration of K+ to an equivalent magnitude (78% of the maximum) relaxant responses to cromakalim were greater in SHR than in WKY. When strips were contracted with 10(-7) M norepinephrine, the precontraction was similar between SHR and WKY, and relaxant responses to cromakalim were greater in SHR. In both strains, the relaxant responses to cromakalim were competitively antagonized by glibenclamide, a blocker of ATP-sensitive K+ (KATP) channels, with a pA2 value of approximately 7.3. Charybdotoxin (10(-7) M), a blocker of Ca(2+)-activated K+ (KCa) channels, did not inhibit the relaxant responses to cromakalim in both strains. Charybdotoxin alone elicited a contraction, which was greater in SHR than in WKY. In resting strips preloaded with 86Rb, the basal 86Rb efflux rate constant was higher in SHR than in WKY. The addition of cromakalim (10(-5) M) to the resting strips increased the 86Rb efflux rate constant in both strains to a similar peak value. The addition of nifedipine (10(-7) M) to the resting strips decreased the basal 86Rb efflux rate constant only in SHR, and concomitantly affected the action of cromakalim in SHR. The results suggest that (1) cromakalim caused arterial relaxation via the opening of KATP channels in both SHR and WKY, (2) although the relaxant effects of cromakalim tended to be greater in SHR than in WKY, the differences were rather small, depended on the precontraction tone and varied with the concentration of the vasoconstrictors, and (3) there was an increased basal Ca2+ influx and a high activation of KCa channels in the resting state of SHR arteries, and these changes might influence the effects of cromakalim.

Endothelium-derived relaxing factor released by 5-HT: distinct from nitric oxide in basilar arteries of normotensive and hypertensive rats

1. The role of the endothelium in cerebrovascular responses to 5-hydroxytryptamine (5-HT) was investigated in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) in vitro. 2. Cumulative addition of 5-HT caused concentration-dependent contractions in ring preparations of SHR basilar arteries; the contractile response was smaller in WKY basilar arteries. 3. Removal of the endothelium enhanced markedly the contractile responses to 5-HT in WKY arteries but had only a slight effect in SHR arteries. The responsiveness to 5-HT in WKY arteries after removal of endothelium was comparable to that in SHR arteries. 4. The endothelium-dependent relaxation induced by acetylcholine in WKY basilar arteries was almost abolished by treatment with 10 microM methylene blue or 10 microM NG-nitro-L-arginine (L-NOARG). However, the response to 5-HT was not affected by treatment with methylene blue, L-NOARG or indomethacin. 5. Application of 10-20 mM K+ or 3.2 mM tetraethylammonium (TEA) did not change significantly, or only increased slightly, the resting tension, but markedly enhanced the contractile response to 5-HT in WKY arteries with endothelium. In contrast, the submaximal response to 5-HT in SHR arteries with endothelium was significantly enhanced by 0.3 mM TEA. 6. In the presence of 1 mM TEA, the application of 10 microM L-NOARG further enhanced the responses of 5-HT in WKY arteries with endothelium. In SHR arteries with endothelium, 10 microM L-NOARG per se enhanced slightly but significantly the responses to 5-HT. 7. These results indicate that 5-HT-induced contraction in basilar arteries is substantially attenuated by an endothelium-dependent mechanism in WKY, but to a much lesser extent in SHR. The major relaxing factor released by 5-HT from endothelium in WKY is distinct from NO and may exert its effect by activating K+ channels.

Effects of aerosol administration of a thromboxane receptor antagonist (S-1452) on experimental asthma in guinea pigs

The importance of thromboxane A2 (TXA2), one of the arachidonate metabolites, in the pathogenesis of bronchial asthma has been emphasized recently. Because aerosolized administration of antiasthmatic drugs is effective and safe, this study examined the effect of aerosolized TXA2 receptor antagonist (S-1452) on allergic bronchoconstriction in passively sensitized and mechanically ventilated guinea pigs. Under the cover of antihistamine, antigen-induced bronchoconstriction was markedly inhibited by pretreatment with aerosolized S-1452 inhalation in a dose-dependent manner. Although aerosolized S-1452 itself provoked weak bronchoconstriction for its partial agonist effect, bronchial responsiveness to inhaled histamine did not change 10 min after S-1452 inhalation. These results indicate that aerosolized S-1452 may be useful in treating bronchial asthma.