INHIBITION OF MITOCHONDRIAL PERMEABILITY TRANSITION BY POLYAMINES ANDMAGNESIUM - IMPORTANCE OF THE NUMBER AND DISTRIBUTION OF ELECTRIC CHARGES

The protective effects of Mg2+ and various natural and synthetic polya mines on the permeability transition of isolated rat liver mitochondri a have been compared. The permeability transition was induced by incub ating the mitochondria in a sucrose medium at pH 7.4 in the presence o f 100 mu M Ca2+ and 1 mM phosphate and was monitored via the release o f endogenous Mg2+, sucrose permeation, mitochondria swelling and the f all of transmembrane potential. By all of these parameters (only the t races of Delta Psi have been reported) spermine fully inhibited the tr ansition at 25 mu M concentration, spermidine and caldine at 250 mu M and Mg2+ at 500 mu M concentration. Both putrescine and dien exhibited only a partial protection even at 2.5 mM concentration. The protectiv e action resulted strictly dependent on the number of the positive cha rges of each cation. In the case of polyamines this number is also det ermined by the nature of the methylene carbon chains of each compound. (C) 1995 Academic Press, Inc.