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Patch-clamp characterization of secretory process in human basophils
T Oshiro1, Y Kakuta, N Maruyama
1First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
International Archives of Allergy and Immunology
|April 1, 1997
Summary
Calcium ions and GTP-gamma-S influence secretion in human basophils. GTP-gamma-S enhances calcium-dependent exocytosis, indicating G protein involvement in this process.
Area of Science:
- Cell Biology
- Immunology
- Physiology
Background:
- Human basophils play a role in allergic reactions and immune responses.
- Exocytosis, the process of cellular secretion, is crucial for these functions.
- Intracellular calcium ions ([Ca2+]i) and guanine nucleotides are known regulators of cellular processes.
Purpose of the Study:
- To investigate the roles of intracellular calcium concentration ([Ca2+]i) and guanosine 5'-o-(3-thiotriphosphate) (GTP-gamma-S) in human basophil secretion.
- To determine the mechanism by which these substances affect granule exocytosis.
Main Methods:
- Patch-clamp technique was employed to study human basophils.
- Intracellular application of varying concentrations of Ca2+ and GTP-gamma-S.
- Measurement of plasma membrane capacitance and conductance to assess exocytosis.
Main Results:
- High intracellular Ca2+ (10 microM) rapidly induced granule dispersion and fusion.
- Lower Ca2+ (2 microM) combined with GTP-gamma-S (100 microM) resulted in gradual granule dispersion and prolonged fusion.
- Ca2+ induced a dose-dependent increase in cell membrane capacitance, confirming Ca2+-dependent exocytosis.
- GTP-gamma-S significantly potentiated Ca2+-induced exocytosis, particularly at lower Ca2+ concentrations.
Conclusions:
- Intracellular calcium concentration is a key regulator of exocytosis in human basophils.
- Guanine nucleotide-binding proteins (G proteins) likely promote Ca2+-dependent exocytosis in these cells.
- These findings elucidate signaling pathways involved in human basophil degranulation.