Imaging of cytosolic Ca2+ transients arising from Ca2+ stores and Ca2+ channels in sympathetic neurons.
Changes in cytosolic free Ca2+ concentration [( Ca2+]i) due to Ca2+ entry or Ca2+ release from internal stores were spatially resolved by digital imaging with the Ca2+ indicator fura-2 in frog sympathetic neurons. Electrical stimulation evoked a rise in [Ca2+]i spreading radially from the periphery to the center of the soma. Elevated [K+]o also increased [Ca2+]i, but only in the presence of external Ca2+, indicating that Ca2+ influx through Ca2+ channels is the primary event in the depolarization response. Ca2+ release or uptake from caffeine-sensitive internal stores was able to amplify or attenuate the effects of Ca2+ influx, to generate continued oscillations in [Ca2+]i, and to persistently elevate [Ca2+]i above basal levels after the stores had been Ca2(+)-loaded.
Lipscombe
D
D
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510.
Madison
D V
DV
Poenie
M
M
Reuter
H
H
Tsien
R W
RW
Tsien
R Y
RY
D000818:Animals; D001572:Benzofurans; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D004553:Electric Conductivity; D004558:Electric Stimulation; D005456:Fluorescent Dyes; D016257:Fura-2; D005728:Ganglia, Sympathetic / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology; D011894:Rana pipiens
D001572:Benzofurans; D015220:Calcium Channels; D005456:Fluorescent Dyes; D002110:Caffeine; D011188:Potassium; D002118:Calcium; D016257:Fura-2