Ionophore-like action of lienomycin on energized membrane of rat-liver mitochondria.

fienoniycin is a new polyene antibiotic produced by Actinomyces distatochromogenes var. lienomycini, exhibiting antifungal, antibacterial and antitumor activity [l-4] . It changes the plasma membrane permeability characteristics of sensitive organisms [5] . The present report deals with so far unobserved sensitivity of rat-liver mitochondria to lienomycin. The antibiotic stimulates mitochondrial State 4 respiration and causes release of protons. The stimulatory effect of lienomycin on respiration is dependent on cation composition of the medium and is severalfold higher in the presence of Tris than K’. In isoosmotic Tris-acetate and diethanolamine acetate lienomycin induces swelling of energized mitochondria. The results obtained indicate that lienomycin exerts ionophore-like action on rat-liver mitochondria in energized state, increasing the permeability of energized mitochondrial membrane to substituted ammonia-cations, such as Tris and diethanolamine.