Effect of temperature on the formation and inactivation of syringomycin E pores in human red blood cells and bimolecular lipid membranes

The effects of temperature on the formation and inactivation of syringomyci n E (SRE) pores were investigated with human red blood cells (RBCs) and lip id bilayer membranes (BLMs). SRE enhanced the RBC membrane permeability of Rb-86 and monomeric hemoglobin in a temperature dependent manner. The kinet ics of Rb-86 and hemoglobin effluxes were measured at different temperature s and pore formation was found to be only slightly affected, while inactiva tion was strongly influenced by temperature. At 37 degrees C, SRE pore inac tivation began 15 min after and at 20 degrees C, 40 min after SRE addition. At 6 degrees C, below the phase transition temperature of the major lipid components of the RBC membrane, no inactivation occurred for as long as 90 min. With BLMs, SRE induced a large current that remained stable at 14 degr ees C, but at 23 degrees C it decreased over time while the single channel conductance and dwell time did not change. The results show that the temper ature dependent inactivation of SRE pores is due to a decrease in the numbe r of open pores. (C) 2000 Elsevier Science B.V, All rights reserved.