Effect of bafilomycin and NAADP on membrane-associated ATPases and respiration of isolated mitochondria of the murine Nemeth-Kellner lymphoma.

The goal of the study was to estimate the effect of a selective V-type H+ -ATPase inhibitor bafilomycin A1 and nicotinic acid adenine dinucleotide phosphate (NAADP) on energetic processes in NK/Ly cell by directly measuring the respiration of isolated mitochondria and ATPase activities. NAADP (7 μM) increased the activity of Na+ /K+ -ATPase in the postmitochondrial fraction of NK/Ly cells, but lower concentration of NAADP decreased it (0.1 and 1 μM). The increase the activity of plasma membrane Ca2+ ATPase (PMCA) under NAADP application (1 and 7 μM) was observed. However, NAADP (1 μM) decreased activities of sarcoendoplasmic reticulum Ca2+ -ATPase (SERCA) and basal Mg2+ -ATPase. Bafilomycin A1 (1 μM) increased the activity of Na+ /K+ -ATPase and potentiated the effect of NAADP (1 μM) on this pump. At the same time, bafilomycin A1 (1 μM) completely prevented all effects of NAADP (1 μM) on activities of PMCA, SERCA, and basal Mg2+ -ATPase, confirming that these effects are dependent on acidic stores. Bafilomycin A1 or NAADP decreased respiratory and oxidative phosphorylation rates in NK/Ly mitochondria when α-ketoglutarate was used as substrate in contrast to succinate. Thus, α-ketoglutarate oxidation is more sensitive to bafilomycin A1 and NAADP influences compared with succinate oxidation. However, bafilomycin A1 + NAADP and any of these compounds separately lead to full uncoupling of mitochondria after ADP addition irrespectively to substrate used. Bafilomycin A1 affects isolated tumor mitochondria more effectively in combination with NAADP. Bafilomycin and NAADP alter some membrane-associated ATPases and inhibit respiration in mitochondria of the Nemeth-Kellner lymphoma. Bafilomycin A1 potentiates the effect of NAADP by inhibiting the mitochondrial energetic process in lymphoma cells and activity of Na+ /K+ -ATPase. The obtained data show promising possibility to use bafilomycin A1 and NAADP as chemotherapeutic agents for lymphoma cells treatment. This is important because lymphomas are seventh most common form of cancer. Today the lymphoma mortality is 15% to 30%, whereas the effectiveness of malignant neoplasms treatment is less than 50%.