Schistosomicides and acetylcholinesterase in the tegument of male Schistosoma japonicum

To observe the influence of some drugs on the AChE and Na+, K+ in the tegument of Schistosoma japonicum, we incubated 40 male at 37 degrees for 1 h in the Bueding medium containing 30 micromol/L trichlorfon, 0.16 mmol/L thiamine, 20 micromol/L nitridazole and 16 micromol/L fuvinazole (5-acetylamide-3-[2-(5-nitro-2-furyl)vinyl]1,2,4-oxadiazole, synthesized by HU Yu-qin of our institute). The worm tegument was then prepared by Triton method. The activity of AChE was determined by colorimetric method and the concentrations of Na+ and K+ were determined by flame photometry. Trichlorfon and thiamine inhibited respectively 90% and 50% activity of AChE in the worm tegument. These 2 drugs increased Na+ contents of the worm tegument. The K+ in the worm tegument treated with trichlorfon was about 30% higher than that of the control group. The AChE, Na+, and K+ of worm tegument were not affected by niridazole and fuvinazole.Ca2+ increased the activity of tegumental AChE. The inhibitory effect of trichlorfon on the worm AChE was decreased in the presence of Ca2+. Forty male released 19.6 (micromol/h)/mg protein into the medium during incubation