Action of praziquantel on calcium transport in Hymenolepis diminuta.

Effect of praziquantel on inward and outward Ca++ fluxes was investigated in Hymenolepis diminuta in glucose supplemented balanced electrolyte solution and under conditions of glucose/Mg++ deficiency. The 45Ca++ uptake in freshly isolated worms presented, generally, a biphasic kinetics. This comprised of an initial fast uptake phase, followed by a continued slower influx. The initial fast kinetics showed insensitivity to or slight stimulation by praziquantel depending on its concentration, and such stimulatory action was particularly prominent under Mg++ deficient condition (P less than 0.01). The subsequent slower 45Ca++ uptake was, however, markedly inhibited by the drug under both these conditions (P less than 0.01). Glucose starvation of the worms resulted in abolition of the fast 45Ca++ influx phase and uniform inhibition by the praziquantel without any indication of initial stimulatory effect (P less than 0.01). The extrusion of 45Ca++ from the label preloaded worms was stimulated by praziquantel under all the conditions investigated (P less than 0.01).