Progesterone-induced Permeability Changes in Rat Liver Lysosomes

Abstract

RAT liver lysosomes have been shown^1,2 to act as “osmotic systems” and to be stable in 0.25 M sucrose solution, presumably as the lysosomal membrane was not permeable to sucrose. Suspension in 0.125 M sodium chloride led to a transient osmotic protection, and graded lysis, where the rate-limiting step was presumed to be entry of the sodium chloride. The effects of fat-soluble vitamins and steroids on lysosomes, in vitro, were extensively studied^3,4. De Duve et al.³ suggested that compounds causing lysis of lysosomes may act by initiating a sequence of events involving altered permeability to solutes, osmotic swelling and rupture. We report here experiments which support the hypothesis that progesterone-induced lysis of lysosomes suspended in 0.25 M sucrose is due to an increased permeability of the membrane to sucrose leading to osmotic rupture.