The recovery and inhibition of stimulus in Vorticella

1.The contractures of Vorticella caused by phenazine methosulphate (10^-5 M), ethacrynic acid (≈ 10^-3 M), or N-t-butyl-5-methyl-isoxazolium perchlorate (10^-3 M), are inhibited by anoxia and by the transhydrogenase inhibitors N,N′-dicyclohexylcarbodiimide (10^-4 M), and 4, 5, 6, 7-tetrachloro-2-trifluoromethyl-benzimidazole (10^-4 M).2.The above transhydrogenase inhibitors also induced contractures at the concentration of 2 × 10^-5 M.3.From about 40 metabolites tested, only β-hydroxybutyrate (10^-5 M) and isocitrate (10^-4 M), hastened the recovery of phenazine methosulphate-exhausted contractures.4.The above data, together with the inefficiency of other metabolic poisons tested, fits the hypothesis of regulation of the contractures by a Ca-ATPase governed by the redox ratio.