title: Influence of fixation and buffer treatment on the release of enzymes from the plasma membrane.
abstract: 1. Pretreatment of frozon cryostat sections with formaldehyde or calcium ions inhibits diffusion of the plasma membrane enzymes 5' nucleotidase, ATP-ase and alkaline phosphatase during incubation. 2. Treatment of fixed sections with different kinds of buffer at 37 degrees C induces diffusion of enzyme activity from the plasma membrane to other sites of the section and into the incubation medium. This buffer influence depends on temperature: at 4 degrees C only a slight diffusion occurs. Addition of phospholipase C, digitonin or taurocholate to the buffer opposes the buffer effect. 3. Pretreatment  of  frozen cryostat sections with a mixture of equal parts of chloroform and acetone give a good fixation of the plasma membrane enzymes 5'-nucleotidase, ATP-ase, alkaline phosphate and leucyl-beta-naphthylamidase. During this treatment the different kinds of lipids present in the membrane are ex-racted equally. After this fixation buffer treatment does not cause a visible diffusion of enzyme activity in the section. Only a slight diffusion (1 till 7 percent) into the buffer solution takes place. 4. The mentioned  treatments open up possibilities to get insight into the membrane anchorage of plasma membrane enzymes.
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis*; D000469:Alkaline Phosphatase / Q000032:analysis*; D000818:Animals; D002021:Buffers; D002462:Cell Membrane / Q000201:enzymology* / Q000648:ultrastructure; D006651:Histocytochemistry; D008099:Liver / Q000201:enzymology / Q000648:ultrastructure; D008297:Male; D009708:Nucleotidases / Q000032:analysis*; D051381:Rats
chemical_list: D002021:Buffers; D009708:Nucleotidases; D000469:Alkaline Phosphatase; D000251:Adenosine Triphosphatases