title: Praziquantel, potassium and 2,4-dinitrophenol: analysis of their action on the musculature of Schistosoma mansoni.
abstract: Praziquantel (PZ) (10(-6) M), an antischistosomal drug, 60 mM K+ and 2,4-dinitrophenol (DNP) induce a rapid contracture of the musculature in adult male S. mansoni. This event is accompanied, except for DNP, by an increased accumulation of 45Ca2+ in the parasite. K+-induced contractures had phasic and tonic components while DNP and PZ produced only tonic contracture of the parasites musculature. The Ca2+ antagonist, D-600 (10(-4) M) as well as La3+ (10 mM) and Co2+ (10 mM) prevented the 45Ca2+ accumulation produced by high K+. La3+ and Co2+ blocked the tension increasing effects of high K+; D-600 blocked only the tonic contractures. D-600 and Co2+ did not prevent the 45Ca2+ increase produced by PZ but La3+ did. D-600 did not block the PZ response but Co2+ and La3+ partially attenuated it. La3+ also partially attenuated the DNP response. Co2+ and D-600 prevented sustained contractures in response to DNP. Thus, although K+, PZ and DNP have the same final effect on the musculature of S. mansoni, it appears that their effects are not mediated by the same mechanisms.
mesh_terms: D019297:2,4-Dinitrophenol; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002412:Cations / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology*; D005711:Gallopamil / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects*; D011188:Potassium / Q000494:pharmacology*; D011223:Praziquantel / Q000494:pharmacology*; D012550:Schistosoma mansoni / Q000187:drug effects*
chemical_list: D002412:Cations; D004140:Dinitrophenols; D007546:Isoquinolines; D005711:Gallopamil; D011223:Praziquantel; D019297:2,4-Dinitrophenol; D011188:Potassium; D002118:Calcium