The rate of penetration of rubidium into living cells of Valonia and its relation to apparent ionic radii

✍ Scribed by Brooks, S. C.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1932
• Tongue: English
• Weight: 449 KB
• Volume: 2
• Category: Article
• ISSN: 0095-9898
• DOI: 10.1002/jcp.1030020209

✦ Synopsis

The permeability of living cells has been likened to that of dried collodion membranes, especially because of the fact that both seem to be more permeable to potassium ions than to those of sodium (Brooks, '31). Since the collodion membranes are increasingly permeable to alkali metal ions in the order of decreasing apparent ionic radii: Li<Na<K <Cs (Michaelis, '25) it was thought by some authors that Cs should penetrate living cells more rapidly than K (Osterhout, '30 b). This group of investigators reported that "little or no Cs penetrated the normal cells" (of a species of Valonia, presumably TT. macrophysa Kiitz) "during a period of over a year" (Cooper, Dorcas, and Osterhout, 'as), and concluded that the permeability of protoplasm to ions is not a function of their apparent ionic radii (Osterhout, '30 a).

This reasoning neglects the probable secondary effects of the ions upon protoplasmic membranes, effects which would not be operative in the case of collodion membranes. Such effects have been studied by Osterhout,l in the case of Laminaria, and are well illustrated in the case of the series Li, Na, K, and Cs by Scarth's experiments on Spyrogyra (Scarth, '25). Scarth found permeability to be increased by Li+ but decreased by Cs+. This may account f o r the relatively slow