IgE receptor-activated calcium permeability pathway in rat basophilic leukemia cells: measurement of the unidirectional influx of calcium using quin2-buffered cells. 1987

C Fewtrell, and E Sherman
Department of Pharmacology, New York State College of Veterinary Medicine, Cornell University, Ithaca 14853.

The intracellular calcium indicator and buffer quin2 has been used to generate a large calcium buffering capacity in the cytoplasm of rat basophilic leukemia cells. Above 3 mM intracellular quin2, there is no further increase in the initial rate of antigen-induced 45Ca uptake, suggesting that 45Ca buffering by quin2 is now sufficient to prevent the immediate efflux of 45Ca from the cells. Thus, the initial rate of 45Ca uptake should reflect the true unidirectional influx of calcium that occurs when immunoglobulin E (IgE) receptors are aggregated by antigen. The antigen-induced calcium permeability pathway appears to be saturable, with a Km of about 0.7 mM and a Vmax of 0.9 nmol of calcium (10(6) cells)-1 min-1. Although net 45Ca uptake reaches a plateau a few minutes after antigen stimulation, the increase in plasma membrane permeability is maintained for at least an hour, provided that receptors for IgE remain aggregated. The initial rate of 45Ca influx correlates well with the subsequent secretion of [3H]serotonin in response to different concentrations of antigen. Both 45Ca uptake and [3H]serotonin secretion are maximal when only 10% of the receptors are occupied with antigen-specific IgE. Thus, 45Ca influx correlates more closely with secretion than with the number of IgE receptors aggregated by antigen.

UI MeSH Term Description Entries
D007073 Immunoglobulin E An immunoglobulin associated with MAST CELLS. Overexpression has been associated with allergic hypersensitivity (HYPERSENSITIVITY, IMMEDIATE). IgE
D007700 Kinetics The rate dynamics in chemical or physical systems.
D007942 Leukemia, Experimental Leukemia induced experimentally in animals by exposure to leukemogenic agents, such as VIRUSES; RADIATION; or by TRANSPLANTATION of leukemic tissues. Experimental Leukemia,Experimental Leukemias,Leukemia Model, Animal,Leukemias, Experimental,Animal Leukemia Model,Animal Leukemia Models,Leukemia Models, Animal
D011961 Receptors, Fc Molecules found on the surface of some, but not all, B-lymphocytes, T-lymphocytes, and macrophages, which recognize and combine with the Fc (crystallizable) portion of immunoglobulin molecules. Fc Receptors,Fc Receptor,Receptor, Fc
D002118 Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D005456 Fluorescent Dyes Chemicals that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags. Flourescent Agent,Fluorescent Dye,Fluorescent Probe,Fluorescent Probes,Fluorochrome,Fluorochromes,Fluorogenic Substrates,Fluorescence Agents,Fluorescent Agents,Fluorogenic Substrate,Agents, Fluorescence,Agents, Fluorescent,Dyes, Fluorescent,Probes, Fluorescent,Substrates, Fluorogenic
D000634 Aminoquinolines Quinolines substituted in any position by one or more amino groups.
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001491 Basophils Granular leukocytes characterized by a relatively pale-staining, lobate nucleus and cytoplasm containing coarse dark-staining granules of variable size and stainable by basic dyes. Basophil
D017455 Receptors, IgE Specific molecular sites on the surface of B- and T-lymphocytes which combine with IgEs. Two subclasses exist: low affinity receptors (Fc epsilon RII) and high affinity receptors (Fc epsilon RI). Antigens, CD23,CD23 Antigens,Fc Receptors, epsilon,Fc epsilon Receptor,Fc epsilon Receptors,IgE Receptor,IgE Receptors,Receptors, Fc epsilon,epsilon Fc Receptor,epsilon Fc Receptors,CD 23 Antigens,CD23 Antigen,Fc epsilon RI,Fc epsilon RII,Immunoglobulin E Receptor,Antigen, CD23,Antigens, CD 23,Fc Receptor, epsilon,Receptor, Fc epsilon,Receptor, IgE,Receptor, Immunoglobulin E,Receptor, epsilon Fc,Receptors, epsilon Fc,epsilon RI, Fc,epsilon RII, Fc,epsilon Receptor, Fc,epsilon Receptors, Fc

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