[Study of stinging crystals in tian nanxing].
OBJECTIVE: To test whether the raphides in Tian Nanxing (Pinellia pedatisecta Schott) caused irritation. METHOD: Scan Electron Microscope and Microscope Oberservation; Animal experimental study. RESULT: Through the comparision of unprocessed Tian Nanxing to processed ones which included 36 h, 72 h, 120 h processed samples, the great modifications in the structure of raphides, especially for the ones with barbs in the processed samples was observed with time course study. A further animal experimental study went to show that the rate of change for raphides with barbs existed a dose-reponse relationship to irritation. CONCLUSION: Investigations of the causes of these reactions showed that raphides of calcium oxalate are, at least in part, responsible for the Tian Nanxing's irritation.