To investigate the presence and the size of different non-mitochondrial Ca2+ pools of Ehrlich ascites tumor cells (EATCs), digitonin-permeabilized cells were allowed to accumulate Ca2+ in the presence of mitochondrial inhibitors and treated with the reticular Ca(2+)-ATPase inhibitor thapsigargin, IP3 and the Ca2+ ionophore A23187. Emptying of thapsigargin-sensitive Ca2+ stores prevented any Ca2+ release by IP3, and, after IP3 addition, little or no Ca2+ was released by thapsigargin. In both instances, a further Ca2+ release was accomplished by A23187. The IP3-thapsigargin-sensitive pool and the residual A23187-sensitive one corresponded to approximately 60 and 37% of non-mitochondrial stored Ca2+, respectively. In intact EATCs, IP3-dependent agonists and thapsigargin discharged Ca2+ pools almost completely overlapping, and A32187 released a minor residual Ca2+ pool. The IP3-insensitive pool appeared to have a relatively low affinity for Ca2+ (below 600 nM). The high affinity, IP3-sensitive Ca2+ pool was discharged in a 'quantal' manner following step additions of sub maximal [IP3], and the IP3-induced fractional Ca2+ release was more marked at higher concentrations of stored (luminal) Ca2+, The IP3-sensitive Ca2+ pool appeared to be devoid of the Ca(2+)-activated Ca2+ release channel since caffeine did not released any Ca2+ in intact and permeabilized EATCs, and Western blot analyses of EATC microsomal membranes failed to detect any known ryanodine receptor isoform.

Gamberucci, A., Fulceri, R., Tarroni, P., Giunti, R., Marcolongo, P., Sorrentino, V., et al. (1995). Calcium pools in Ehrlich carcinoma cells. A major, high affinity Ca2+ pool is sensitive to both inositol 1,4,5-trisphosphate and thapsigargin. CELL CALCIUM, 17(6), 431-441 [10.1016/0143-4160(95)90089-6].

Calcium pools in Ehrlich carcinoma cells. A major, high affinity Ca2+ pool is sensitive to both inositol 1,4,5-trisphosphate and thapsigargin

Gamberucci, A.;Fulceri, R.;Giunti, R.;Marcolongo, P.;Sorrentino, V.;Benedetti, A.
1995-01-01

Abstract

To investigate the presence and the size of different non-mitochondrial Ca2+ pools of Ehrlich ascites tumor cells (EATCs), digitonin-permeabilized cells were allowed to accumulate Ca2+ in the presence of mitochondrial inhibitors and treated with the reticular Ca(2+)-ATPase inhibitor thapsigargin, IP3 and the Ca2+ ionophore A23187. Emptying of thapsigargin-sensitive Ca2+ stores prevented any Ca2+ release by IP3, and, after IP3 addition, little or no Ca2+ was released by thapsigargin. In both instances, a further Ca2+ release was accomplished by A23187. The IP3-thapsigargin-sensitive pool and the residual A23187-sensitive one corresponded to approximately 60 and 37% of non-mitochondrial stored Ca2+, respectively. In intact EATCs, IP3-dependent agonists and thapsigargin discharged Ca2+ pools almost completely overlapping, and A32187 released a minor residual Ca2+ pool. The IP3-insensitive pool appeared to have a relatively low affinity for Ca2+ (below 600 nM). The high affinity, IP3-sensitive Ca2+ pool was discharged in a 'quantal' manner following step additions of sub maximal [IP3], and the IP3-induced fractional Ca2+ release was more marked at higher concentrations of stored (luminal) Ca2+, The IP3-sensitive Ca2+ pool appeared to be devoid of the Ca(2+)-activated Ca2+ release channel since caffeine did not released any Ca2+ in intact and permeabilized EATCs, and Western blot analyses of EATC microsomal membranes failed to detect any known ryanodine receptor isoform.
Gamberucci, A., Fulceri, R., Tarroni, P., Giunti, R., Marcolongo, P., Sorrentino, V., et al. (1995). Calcium pools in Ehrlich carcinoma cells. A major, high affinity Ca2+ pool is sensitive to both inositol 1,4,5-trisphosphate and thapsigargin. CELL CALCIUM, 17(6), 431-441 [10.1016/0143-4160(95)90089-6].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/21136
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