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

Abstract
In permcabilized rat hepatocytcs a maximal concentration (25 μM) of 2,5-di-( tert -butyl)-1,4-benzohydroquinone (tBuBHQ) mobilized 70% of sequestered Ca 2+ and a half-maximal effect was produced by 1.7 μM tBuBHQ. Inositol 1,4,5-trisphosphate (Ins(1,4,5) P 3 ) 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) P 3 -sensitive stores. We conclude that the Ins(1,4,5) P 3 -sensitive stores arc 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) P 3 -sensitive and -insensitive Ca 2+ stores though it may provide opportunities to design more selective agents.