title: Haemonchus contortus and Ostertagia circumcincta: fenbendazole treatment and abomasal permeability changes in sheep.
abstract: Effects of fenbendazole (7.5 mg/kg of body weight infused during 90 minutes) on abomasal transmural potential difference (PD), pH, and ionic concentrations were determined in 8 lambs fitted with permanent abomasal cannulae. Four sheep were treated before inoculation and on day 28 after inoculation, with 200,000 3rd-stage Ostertagia circumcincta larvae and 4 others were similarly inoculated with 15,000 3rd-stage Haemonchus contortus larvae. In worm-free lambs, the unique effect was an increase in Na+ concentration of the abomasal contents. The O circumcincta or H contortus-inoculated lambs had an increase in PD, pH, and Na+ concentrations. Treatment further increased these concentrations, but the effects on PD occurred and ceased earlier in sheep inoculated with O circumcincta than in those inoculated with H contortus. The results indicated that part of the changes were linked to substances produced by the parasites or by the host. The increase in PD and pH was associated with a decrease in K+ concentration and indicated that these substances stimulated HCO3- transfer.
mesh_terms: D000018:Abomasum / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology*; D004594:Electrophysiology; D005273:Fenbendazole / Q000494:pharmacology* / Q000627:therapeutic use; D006188:Haemonchiasis / Q000188:drug therapy / Q000503:physiopathology / Q000662:veterinary*; D006863:Hydrogen-Ion Concentration; D010029:Ostertagiasis / Q000188:drug therapy / Q000503:physiopathology / Q000662:veterinary*; D010539:Permeability; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy / Q000503:physiopathology*; D012964:Sodium / Q000378:metabolism; D014252:Trichostrongyloidiasis / Q000662:veterinary*
chemical_list: D001562:Benzimidazoles; D005273:Fenbendazole; D012964:Sodium