RT Journal Article SR Electronic(1) A1 Grešík, Miroslav A1 Kolarova, Nadežda A1 Farkaš, VladimírYR 1991 T1 Hyperpolarization and intracellular acidification in Trichoderma viride as a response to illumination JF Microbiology, VO 137 IS 11 SP 2605 OP 2609 DO https://doi.org/10.1099/00221287-137-11-2605 PB Microbiology Society, SN 1465-2080, AB Using indirect methods based on uptake of [3H]tetraphenylphosphonium cation and [14C]benzoic acid by cells of the fungus Trichoderma viride we found that the illumination-induced transient hyperpolarization of the plasma membrane is followed immediately by a rapid temporary decrease in intracellular pH. Hyperpolarization and intracellular acidification were completely suppressed by 150 mm-KCI and by the K+-ionophore valinomycin. The light-induced acidification of the cytoplasm was not observed in the presence of the cytochrome respiratory chain inhibitors antimycin A and mucidin. Based on these results, we hypothesize that the hyperpolarization of the cells is the consequence of an efflux of K+ through a light-activated K+-channel in the plasma membrane. The loss of positive charge in the cytoplasm caused by this efflux of cations is counterbalanced by H+ originating from the light-activated mitochondrial respiratory chain., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-137-11-2605