2,5‐Di‐(tert‐butyl)‐1,4‐benzohydroquinone mobilizes inositol 1,4,5‐trisphosphate‐sensitive and ‐insensitive Ca²⁺ stores

Abstract

In permeabilized rat hepatocytes a maximal concentration (25/tM) of 2, mobilized 70% of sequestered Ca 2+ and a half-maximal effect was produced by 1.7/iM tBuBHQ. Inositol 1,4,5-trisphosphate (Ins(l,4,5)P3) stimulated release of about 40% of the intracellular Ca 2+ stores. Combined applications of a range of tBuBHQ concentrations with a maximal concentration of Ins(1,4,5)P 3 demonstrated that tBuBHQ has slight selectivity for the Ca 2÷ transport process of the Ins(1,4,5)P3-sensitive stores. We conclude that the Ins( 1,4,5)P3-sensitive stores are a subset of those sensitive to tBuBHQ and that the latter is therefore unlikely to prove useful as a tool to discriminate Ins(1,4,5)P3-sensitive and -insensitive Ca 2÷ stores though it may provide opportunities to design more selective agents.Inositol 1,4,5-trisphosphate; Intracellular Ca 2÷ store; 2,