[Calcium antagonistic effect of Xanthotoxol on isolated guinea pig atria].

OBJECTIVE: To study the mechanism of depressant effect of xanthotoxol (XT) on contractility in the isolated guinea pig atria. METHODS: The contractile force of the isolated left atria was determined by tension recording method. RESULTS: In the experiments on contractility of the left atria XT and Verapamil (Ver) significantly depressed the positive staircase phenomena, which was reversed by Ver but not by XT. However, the post-rest potentiation of myocardial contraction in the left atria was only markedly decreased by XT but not by Ver. Furthermore, XT not only attenuated the positive inotropic action, but also delayed the following toxicity response induced by ouabain in the isolated left atria. CONCLUSION: XT blocked not only the voltage dependent calcium channel, but also the receptor operated calcium channel in the isolated guinea pig atria.

Anti-inflammatory effect and mechanism of osthole in rats.

OBJECTIVE: To investigate the anti-inflammatory effect and mechanism of osthole (Ost). METHODS: Carrageenan -induced hind paw edema in rats were prepared. The nitric oxide synthase (NOS) activity was measured by NADPH -diaphoras stain assay, nitric oxide (NO) content by Griess diazotization assay, malondialdehyde (MDA) content by Thibabituric acid mehtods. And PG content was assaied by Uv -vis spectrophotometry with 278 nm after 0.5 mol/L KOH methanol reagent dissimilating. RESULTS: The increase in NO2(-) observed 4h after carrageenan administration was inhibited by Ost from 524.4 +/- 58.7/micromol/L(-1) NO2(-) for carrageenan alone to 461.5 +/- 68. 8,353.8 +/- 111.0/micromol/L NO2(-) for, respectively, carrageenan administered in combination with 50 mg/kg or 100 mg/kg Ost. It suggested Ost suppress inflammatory responses on NO levels in a dose -dependent manner (P < 0.05). In the presence of Ost 100 mg/kg, NOS activities remained at near blank control levels. Meanwhile results showed reduced malondialdehyde production (MDA) in the presence of Ost, which is one of the byproducts of lipid peroxidation. Ost 50, 100 mg/kg markedly suppressed the generation of PG in inflamed paws. CONCLUSION: Ost presents anti-inflammatory activities at the used models. The effects may be associated to a supression of content of PG, NO, MDA and cNOS activity by inhibition of calcium entry and elevating cGMP levels way.

[Effect of xanthnotoxol on contraction of rabbit thoracic aortic strips].

OBJECTIVE: To study the effect of xanthnotoxol (XT) on contractility of rabbit thoracic aorta strips and its relationship with Ca2+. METHODS: Routine experimental methods for isolated thoracic aorta strips were adopted. RESULTS: XT and verapamil (Ver) can make the dose-response curve of rabbit thoracic aorta strips induced by NE, KCl, CaCl2 shifed right (the pD'2 of KCl and CaCl2 value was 3.58 +/- 0.07 and 4.12 +/- 0.12) and depressed the maximal responses. Like verapamil (Ver), it is accomplished by calcium antagonism. XT could selectively block the voltage dependence calcium channel (VDC), and have no effect on the receptor operated calcium channel (ROC). CONCLUSION: It suggested XT had selectly blocking effect on voltage dependence calcium channel.