Di- and triphosphoinositides were quantitatively extracted from guinea-pig brain with a mixture of chloroform, methanol and 2 M KCl. The extracts were almost colourless and were not severely contaminated with chloroform-insoluble material or inorganic phosphate. The same technique did not extract polyphosphoinositides from guinea-pig liver or from several other tissues. Analysis of the residue remaining after extraction of lipids from rat liver and of phosphate ester fractions obtained from this tissue by acid hydrolysis showed only low concentrations of inositol attributable to inositol di- and triphosphates. This observation is not consistent with a previous report of relatively high concentrations of these esters in rat liver.
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