Patch-clamp characterization of secretory process in human basophils.
The effects of the intracellular Ca2+ concentration ([Ca2+]i) and a nonhydrolyzable guanosine triphosphate, guanosine 5'-o-(3-thiotriphosphate) (GTP-gamma-S), on secretion were studied by a patch-clamp technique in human basophils. When 10 microM Ca2+ were applied intracellularly, the granules dispersed rapidly, moved vigorously and fused to the cell membrane in 5 min. When the cells were exposed to 2 microM [Ca2+]i and 100 microM GTP-gamma-S, the granules dispersed gradually and granule fusion continued for 7-10 min. The plasma membrane conductance did not appreciably change with either 10 microM [Ca2+]i alone or 2 microM [Ca2+]i + 100 microM GTP-gamma-S. Intracellular application of Ca2+, 1-10 microM, caused a dose-dependent increase in cell membrane capacitance, which reflects granule membrane fusion, indicating exocytosis in a Ca2+ concentration-dependent manner. The addition of 100 microM GTP-gamma-S promoted an increase in the plasma membrane capacitance at concentrations from 0.1 to 2 microM [Ca2+]i and at 2 microM [Ca2+]i the increase was 4.4 times greater than that with 2 microM [Ca2+]i alone. These results indicate that certain G protein(s) promote Ca2+-dependent exocytosis in human basophils.
Oshiro
T
T
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Kakuta
Y
Y
Maruyama
N
N
Fushimi
T
T
Okayama
H
H
Tamura
G
G
Shimura
S
S
Shirato
K
K
D001491:Basophils / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002469:Cell Separation; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006801:Humans; D008561:Membrane Fusion / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques
D016244:Guanosine 5'-O-(3-Thiotriphosphate); D002118:Calcium