Cаlіx[4]аrene С-956 is effective inhibitor of Н(+)-Сa(2+)-exchanger in smooth muscle mitochondria

it was shown that calix[4]arene c-956 exhibited a pronounced concentration-dependent (10-100 μm) inhibitory effect on the h+-ca2+-exchanger of the inner mitochondrial membrane of rat uterine myocytes (Ki 35.1 ± 7.9 μm). the inhibitory effect of calix[4]arene c-956 was accompanied by a decrease in the initial rate (V0 ) and an increase in the magnitude of the characteristic time (τ1/2) of the ΔрН-induced Са 2+ release. At the same time, it did not affect the potential-dependent accumulation of ca2+ in mitochondria. thus, the action of calix[4]arene c-956 might be directed on increasing the concentration of ca ions in the mitochondrial matrix. the calculation of basic kinetic parameters of the ca2+ transport from isolated organelles (in the case of its non-zero stationary level), based on changes in fluorescence of ca2+-sensitive dye Fluo-4 Am in mitochondria was performed. the proposed approach can be used for the kinetic analysis of the exponential decrease of the fluorescence response of any probes under the same experimental conditions.