Single-cell analysis of the mitogen-induced calcium responses of normal and protein kinase C-depleted Swiss 3T3 cells.
Single-cell fluorescence image analysis has been used to characterize the mitogen-induced increases in intracellular free [Ca2+] ([Ca2+]i) in control and protein kinase C-depleted Swiss 3T3 cells. More than 80% of the control cells exhibited fast, transient responses to bombesin, vasopressin, or prostaglandin F2 alpha (PGF2 alpha). In contrast, the [Ca2+]i responses induced by platelet-derived growth factor (PDGF) were markedly more heterogeneous, slower, and often biphasic, with fewer cells (60-70%) responding. The peak [Ca2+]i values obtained in response to each mitogen showed substantial variation between cells. Brief pretreatment of the cells with 12-O-tetradecanoyl phorbol 13-acetate (TPA) reduced the [Ca2+]i responses to bombesin, but did not affect the responses to PDGF. Long-term pretreatment of the cells with TPA to down-modulate protein kinase C resulted in substantially prolonged [Ca2+]i responses to bombesin, vasopressin, and PGF2 alpha, but had no such effect on the responses to PDGF. We conclude that differences between the [Ca2+]i responses to bombesin and PDGF, previously reported using cell populations, reflect differences occurring in individual cells, and that the [Ca2+]i responses to bombesin, vasopressin, and PGF2 alpha (but not PDGF) are subject to feedback inhibition via protein kinase C.
Corps
A N
AN
Department of Biochemistry, AFRC Institute of Animal Physiology, Cambridge, U.K.
Cheek
T R
TR
Moreton
R B
RB
Berridge
M J
MJ
Brown
K D
KD
D016475:3T3 Cells / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001839:Bombesin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015237:Dinoprost / Q000494:pharmacology; D051379:Mice; D008934:Mitogens / Q000494:pharmacology*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014667:Vasopressins / Q000494:pharmacology
D008934:Mitogens; D010982:Platelet-Derived Growth Factor; D014667:Vasopressins; D015237:Dinoprost; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D001839:Bombesin; D002118:Calcium