Measurement of intracellular Ca2+ in the bullfrog sympathetic ganglion cells using fura-2 fluorescence.
The intracellular free Ca2+ concentration ([Ca2+]i) of the bullfrog sympathetic ganglion cell was measured with fura-2 fluorescence under various conditions, and compared with changes in membrane potential recorded with an intracellular electrode. The [Ca2+]i was 109 nM on average under the resting condition and increased by raising the extracellular K+, stimulating repetitively the pre- or post-ganglionic nerve, or by applying acetylcholine or muscarine. Since all these procedures depolarized the cell membrane, most of the rise in [Ca2+]i could be the result of opening of voltage-dependent Ca2+ channels. However, Ca2+ entries through nicotinic acetylcholine receptor channels and the channel activated by the muscarinic acetylcholine receptor were also indicated by considering the threshold for the opening of voltage-dependent Ca2+ channels (for both entries) or a limited number of the cells showing the latter response.
Nohmi
M
M
Department of Physiology, Saga Medical School, Japan.
Kuba
K
K
Ogura
A
A
Kudo
Y
Y
D000109:Acetylcholine / Q000494:pharmacology; D000320:Adrenergic Fibers / Q000032:analysis / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001572:Benzofurans; D002118:Calcium / Q000502:physiology*; D004558:Electric Stimulation; D016257:Fura-2; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009116:Muscarine / Q000494:pharmacology; D011892:Rana catesbeiana; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000502:physiology
D001572:Benzofurans; D011950:Receptors, Cholinergic; D009116:Muscarine; D000109:Acetylcholine; D002118:Calcium; D016257:Fura-2