RESUMO
Aim To observe the effect of three steroidal saponins on the M-cholinoceptor density of cultured rat myocardiac cells. Methods The time course of M-cholinoceptor density was observed and diosgenin (DIO),timosaponin aglycone (ZMS,S-configuration) and XMS,a stereoisomeric compound of ZMS in C-25 methyl group,R-configuration) were added to the culture medium from the 12th day of culture at three final concentration of 10~(-7),10~(-6) and 10~(-5) mol?L~(-1),and the M-cholinoceptor density was measured on the 16th day with radioligand binding assay. Results The density of M-cholinoceptor increased gradually at the beginning of culture,reached a plateau at 4～10 days,and then dropped gradually. On the 16th day of culture,the M-cholinoceptor density was about 60% of the plateau value.The up-regulation effect of ZMS on the density of cultured rat myocardiac cells on the 16 th day was only significant at a final concentration of 10~(-5) mol?L~(-1). On the contrary,XMS was effective even when its final concentration was as low as 10~(-7) mol?L~(-1). DIO showed no effect on the M-cholinoceptor density at any of its three concentration. Conclusion The above results indicate that XMS with lower concentration showed similar effect on the M-cholinoceptor density of cultured mylcardiac cells as that of ZMS with more higher concentration.