The role of endoplasmic Ca2+-functional unit in P2Y-receptors signal transduction processes in Chironomus plumosus larvae secretary cells of salivary glands
ІP3-dependent Са2+-channels inhibitor 2-АPB in low concentrations (1–10 µmol/l) causes increase of stored Са2+ content in salivary glands of Chironomus plumosus larvae, both incubated as in nominally calcium-free medium and in the medium with physiological Са2+ concentration. This effect is caused b...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Львівський національний університет імені Івана Франка
2009-12-01
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| Series: | Біологічні студії |
| Subjects: | |
| Online Access: | http://publications.lnu.edu.ua/journals/index.php/biology/article/view/484 |
| Summary: | ІP3-dependent Са2+-channels inhibitor 2-АPB in low concentrations (1–10 µmol/l) causes increase of stored Са2+ content in salivary glands of Chironomus plumosus larvae, both incubated as in nominally calcium-free medium and in the medium with physiological Са2+ concentration. This effect is caused by inhibition of ІP3-dependent Са2+-channels, decreasing of Ca2+-release from endoplasmic reticulum which results in shift of endoplasmic Са2+-functional unit equilibrium in the direction of Са2+ accumulation in the intracellular stores. After incubation of glands with 2-APB in hypercalcium medium decrease of Са2+ content in secretory cells was observed. Presence of high concentration of 2-APB (20–100 µmol/l) in incubation medium leads to decrease of Са2+ content in secretory cells independently of Са2+ concentration. This effect most probably is caused by the inhibition of SERCA Са2+-pump, which is a part of endoplasmic Са2+-functional unit, decrease of Ca2+ uptake resulting in shift of equilibrium in direction of release of stored Са2+. Application of ATP or ADP in the nominal Ca2+-free medium induces a decrease of Са2+ content in the secretory cells as a result of P2Y-receptors activation. At the same time, presence of 2-APB (10 µmol/l) in nominally Ca2+-free medium abolishes the ATP-induced Са2+ release of Са2+, and did not influence ADP-induced decrease of Са2+ concentration in the secretory cells. According to the obtained data, we assume the presence of two subtypes of Р2Y-receptors in secretory cells of Chironomus plumosus larvae salivary glands. Receptors of the first subtype (P2YATP) have higher affinity to ATP and are coupled with IP3-dependent Са2+-channels. Activation of endoplasmic Са2+-functional unit is a basic mechanism of the signal transduction following activation of this subtype of receptors. Receptors of the second subtype (P2YADP) have higher affinity to ADP and exert their functions through other mechanism. Addition of 2-APB to hipercalcium media abolishes the ATP- and ADP-induced changes in Са2+ content in glands' tissue due to changes in the integrity of endoplasmic Са2+-functional unit. |
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| ISSN: | 1996-4536 2311-0783 |