Loss of membrane transport ability in leaf cells and release of protein as a result of osmotic shock

Osmotic shock severely reduces the ability of aged strips of Phaseolus vulgaris leaves to take up α-aminoisobutyric acid, an amino acid analogue which is known to be transported by a specific mechanism. Cold osmotic shock, i.e., transfer from 0.5 m sucrose at 25 C to H₂O at 2 C, decreases α-aminoisobutyric acid uptake almost to zero. Substitution of 10⁻³m ethylenediaminetetraacetate for the sucrose, i.e., treatment which does not involve plasmolysis, produces a similar, but less severe, effect.