title: Coenzyme dependent suppression of 2,2-PDS induced contractures in Spirostomum.
abstract: Spirostomum ambiguum was stimulated to contract by addition of the thiol inhibitor, 2,2-dithiobispyridine (PDS), which depletes intracellular reducing equivalents which are generated by coenzyme dependents reactions. PDS induced contractures were not suppressed after 2--4 h of pre-incubation in a medium enriched with ascorbic acid, thiamine, or riboflavin, singly. Two h of incubation with nicotinamide did not suppress contractures; however, 50% suppression occurred after 3 h incubation. Incubation of the cells in a medium enriched with all four coenzymes for up to 4 h, resulted in the suppression of PDS induced contractures to a level as low as 30% of control values. Suppression of contractures by the mixed coenzymes was concentration dependent. Cells that were stimulated with PDS and contracting, exhibited a 50% suppression of contractures within 3 min after transfer to a complementary medium enriched with mixed coenzymes. These results suggest that coenzymes interact synergistically with cellular metabolic processes to inhibit pharmacodynamic responses to PDS.
mesh_terms: D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D016798:Ciliophora / Q000187:drug effects* / Q000502:physiology; D003067:Coenzymes / Q000494:pharmacology*; D004220:Disulfides / Q000494:pharmacology*; D004357:Drug Synergism; D009068:Movement / Q000187:drug effects; D009536:Niacinamide / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology*; D012256:Riboflavin / Q000494:pharmacology; D013439:Sulfhydryl Reagents / Q000494:pharmacology*; D013831:Thiamine / Q000494:pharmacology
chemical_list: D003067:Coenzymes; D004220:Disulfides; D011725:Pyridines; D013439:Sulfhydryl Reagents; D009536:Niacinamide; D015082:2,2'-Dipyridyl; D001205:Ascorbic Acid; D012256:Riboflavin; D013831:Thiamine