[Experimental study on antagonism of ginkgolides against effect of platelet-activating factor on lung strip of guinea pigs].
OBJECTIVE
To investigate the action of ginkgolides antagonizing the contraction of guinea pigs' lung strip induced by the mixture of platelet-activating factor (PAF) and platelets and its effect of preventing the PAF caused damage of beta-adrenergic receptors.


METHODS
The contraction of guinea pigs' isolated lung strip was measured.


RESULTS
The mixture of PAF and platelet could produce a serious contraction of lung strip, the IC50 reached 4.69 x 10(-7) mol/L, while the contraction induced by PAF alone was relatively mild, its IC50 only 6.66 x 10(-4) mol/L, the difference between them was significant (P < 0.05). When the platelets were preincubated with ginkgolides for 10 minutes in Tris-Tyrode's buffered saline, the effects of PAF and platelets mixture were significantly inhibited (P < 0.05). Exposure of guinea pigs' lung strip to PAF in vitro resulted in a loss of beta-adrenergic receptors and weakened its respones to isoproterenol, a receptor activating factor, the EC50 would be increased from 1.38 x 10(-6) mol/L to 6.25 x 10(-6) mol/L, P < 0.05. This effect of PAF could also be inhibited by ginkgolides (P < 0.05).


CONCLUSIONS
Ginkgolides is a promising PAF antagonist, and might be used in treating bronchial asthma.
D000818:Animals; D004224:Diterpenes; D005260:Female; D046934:Ginkgolides; D006168:Guinea Pigs; D007783:Lactones / Q000494:pharmacology*; D008168:Lung / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors*; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000378:metabolism