Influence of alkali metal cations on the transport of calcium by phosphatidate in multi-phase systems

✍ Scribed by R.N. Reusch

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 805 KB
• Volume: 54
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(90)90015-j

✦ Synopsis

The effects of alkali metal cations on the rates at which Ca ~ and phosphatidic acid were cotransported from aqueous to hydrocarbon medium were examined. The alkali metal cations remained in the aqueous phase yet specifically influenced the transport of Ca 2÷ into the hydrocarbon solvent. For the physiological cations, Na ÷ and K*, there were critical concentration ranges in which small changes in concentration effected sharp changes in transport rates. The maximal rate observed with Na ÷ was an order of magnitude greater than that with K+; however, unlike Na ÷, K ÷ promoted low levels of transport below the critical concentration range. Li ÷ effected only low levels of transport even at high concentrations, whereas Rb* and Cs ÷ induced transport at rates proportional to their concentrations. These results are discussed in terms of a classical ionophore model for the complex composed of a neutral phosphatidic acid dimer bridged by Ca 2÷.