Antidiabetic effect of Oenanthe javanica flavone

AIM

To study the antidiabetic effect of Oenanthe javanica flavone (OjF).

METHODS

Mice were injected i.v. with alloxan 90 mg.kg-1 to induce diabetes. Blood glucose, serum lipid, and pancreatic amylase were determined with Automatic Biochemistry Analysor. Serum insulin was determined by radioimmunoassay. The pancreas and islets were examined under microscope.

RESULTS

OjF 200 mg.kg-1 reduced the blood glucose in normal mice from 0.5 to 6 h after a single administration ig. OjF 200 and 400 mg.kg-1 ig daily for 10 d decreased the blood glucose in alloxan-induced hyperglycemic mice (P < 0.05, P < 0.01). OjF promoted the release of insulin both in normal and in diabetic mice. OjF decreased serum triglyceride and raised the lowered pancreatic amylases in diabetic mice (P < 0.01, P < 0.01). The islet-injured changes of OjF-treated group were similar to those of control in histology examination, but to a lesser degree.

CONCLUSION

OjF possessed the hypoglycemic and hypotriglyceride actions, mainly concerned with promoting release of insulin from B-cells in islets of langerhans.

Group I secreted PLA2 and arachidonic acid metabolites in the maintenance of cat LES tone

Spontaneous tone of in vitro lower esophageal sphincter (LES) circular muscle is associated with elevated levels of arachidonic acid (AA), PGF(2alpha), and increased [35S]guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) binding to Gq-, Gi3-, and G(i1/i2)-like G proteins. Tone and AA levels were reduced by inhibitors of a pancreatic-like (group I) secreted phospholipase A2 (sPLA2), by the cyclooxygenase inhibitor indomethacin, and by the thromboxane A2 antagonist SQ-29548. In addition, pertussis toxin (PTX) reduced LES tone, confirming a role of PTX-sensitive G proteins in maintenance of LES tone. PGF(2alpha) contracted LES smooth muscle (strips and cells) and increased [35S]GTPgammaS binding to Gq and Gi3 in solubilized LES circular muscle membranes. PGF(2alpha)-induced contraction of LES permeable muscle cells was inhibited by Gq and Gi3 but not by G(i1/i2) and Go antibodies. The thromboxane A2 analog U-46619 contracted LES smooth muscle and increased Gq binding. U-46619-induced contraction was inhibited by Gq but not by Gi3, G(i1/i2), and Go antibodies. LES tone and [(35)S]GTPgammaS binding were significantly reduced by indomethacin. We conclude that group I sPLA2 may mediate "spontaneous" LES tone by producing AA, which is metabolized to PGF(2alpha) and thromboxane A2. These AA metabolites activate receptors linked to Gi3 and Gq to maintain LES contraction.

Inhibition of nitric oxide synthesis increases the secretion of endothelin-1 in vivo and in cultured endothelial cells

The aim of this study is to investigate the effects of nitric oxide, formed from L-arginine, on the production of endothelin-1 in vivo and in cultured endothelial cells. In mechanically ventilated anesthetized dogs (n = 5), mean pulmonary arterial pressure (PAPm) and pulmonary vascular resistance (PVR) during hypoxic ventilation (FIO2 = 0.10) was 25 +/- 3.1 kPa and 68.7 +/- 10.2 kPa.s/L respectively. NG-nitro-L-arginine methylester (L-NAME), an inhibitor of nitric oxide synthase, increased the peak value of PAPm and PVR during hypoxic ventilation to 36.6 +/- 4.7 kPa and 158.4 +/- 25 kPa.s/L and its effect lasted for 2-3 hours. Meanwhile, plasma endothelin-1 level in the femoral artery increased by 20.9 +/- 7.1, 25.6 +/- 7.7, 28.6 +/- 7.9 pg/ml at the 60th, 120th, 180th minute after the injection of L-NAME respectively (P < 0.05 vs hypoxic control before the injection). In cultured endothelial cells from umbilical veins, endothelin-1 level of culture medium in control group was 35.1 +/- 5.9 pg/10(5) cells/ml (n = 9). L-NAME increased endothelin-1 level to 42.8 +/- 4.9pg/10(5) cells/ml (n = 9, P < 0.05) in case of 10(-11) mol/L and to 43.0 +/- 4.7 pg/10(5) cells/ml in case of 10(-7) mol/L (n = 9, P < 0.05). These findings indicate that endogenous nitric oxide is an inhibitory modulator of hypoxic pulmonary vasoconstriction and that nitric oxide inhibits the production of endothelin-1 in vivo and in cultured vascular endothelial cells.

[Pulmonary nocardia infection]

Four cases of pulmonary Nocardia infection were reported and the 22 cases reported in our country between 1980 and 1993 were analyzed together for the purpose of revealing the clinical picture of this disease in China. There was approximately a ratio of two male patients to one female (18:8) with a mean age of 40 years in this series of patients. Various underlying diseases were found as predisposing factors in 69% (18/26) of the cases. 34.5% (9/26) of the cases had a history of corticosteroid therapy. Pleural effusion was identified in 50% (13/26) of the patients. 38% (10/26) of the patients died. Patients with primary pulmonary Nocardia infection had a better prognosis than those with secondary infection. Appropriate culture media, sufficient culture time and repeated cultures were recommended to improve the positive identification rate of this special causative agent. The sulfonamides were the drugs of first choice along with prompt drainage of thoracic empyema and abscess.

[Inhibition of endogenous nitric oxide synthesis enhances acute hypoxic pulmonary vasoconstriction]

The objective of this study was to observe the role of endogenous nitric oxide, formed from L-arginine, in the regulation of acute hypoxic pulmonary vasoconstriction by inhibiting its synthesis with the false substrate NG-nitro-L-arginine methyl ester (L-NAME) in anesthetized dogs. L-NAME (1 mg/kg, 5 mg/kg, 15 mg/kg) significantly increased the mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) during hypoxic ventilation (FiO2 = 0.10) and its action lasted for 90-180 minutes. The maximum increase value (MIV) of hypoxic mPAP in three groups (4 dogs each group) is 1.1 +/- 0.2, 1.5 +/- 0.3, 1.6 +/- 0.4 kPa (1 kPa = 7.5 mmHg), respectively, while that of hypoxic PVR is 58.4 +/- 15.6, 99.3 +/- 28.8, 78 +/- 4.0 kPa.s/L (all P < 0.05 vs hypoxic control before the injection). The increase percent of hypoxic mPAP and PVR induced by L-NAME (15 mg/kg) was 45.23 +/- 5.78% and 133.2 +/- 35.22% 30 minutes after the injection, which was more remarkable than that of mPAP and PVR (18.83 +/- 5.63%, 84.13 +/- 22.67%, respectively) by L-NAME (1 mg/kg). L-arginine (0.5 g/kg) reversed the effect of L-NAME (5 mg/kg) on mPAP and PVR at hypoxic ventilation within one hour. L-NAME also markedly increased hypoxic mean arterial blood pressure at the dose of 15 mg/kg (MIV 2.7 +/- 0.7 kPa) and systemic vascular resistance at the three separate doses (MIV 354.4 +/- 99.7, 456.2 +/- 105, 361.5 +/- 70 kPa x s/L, respectively), meanwhile it remarkably decreased cardiac output and heart rate during hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)