Effects of acetylcholine, TSH and other stimulators on intracellular calcium concentration in dog thyroid cells.
The intracellular free calcium concentration, [Ca2+]i, has been measured in dog thyroid cells using the fluorescent Ca2+-indicator, quin2. Acetylcholine or its non-hydrolyzable analog, carbamylcholine rapidly increased [Ca2+]i by 40 +/- 4% (mean +/- SE) over the basal level of 81 +/- 2 nM. This increase was totally abolished by atropine, a muscarinic cholinergic receptor blocker, but was not influenced by verapamil, a voltage dependent-calcium channel blocker. Depletion of extracellular Ca2+ by the addition of EGTA, diminished but did not abolish the response to carbamylcholine. These data suggest that cholinergic effectors increase [Ca2+]i by mobilization of Ca2+ from intracellular stores rather than from an influx of Ca2+. Addition of TSH, isoproterenol, phorbol ester, dibutyryl cyclic GMP or cyclic AMP did not elicit any change in [Ca2+]i suggesting that their action may not involve any mobilization of intracellular Ca2+. These data provide direct evidence that in the thyroid cell, cholinergic agents act via their receptors to cause a rapid increase in [Ca2+]i, which may mediate their metabolic effects.
D000109:Acetylcholine / Q000494:pharmacology*; D000634:Aminoquinolines; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004285:Dogs; D004533:Egtazic Acid / Q000494:pharmacology; D005456:Fluorescent Dyes; D066298:In Vitro Techniques; D013050:Spectrometry, Fluorescence; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology
D000634:Aminoquinolines; D005456:Fluorescent Dyes; D004533:Egtazic Acid; D001285:Atropine; D002217:Carbachol; D013972:Thyrotropin; D014700:Verapamil; D000242:Cyclic AMP; D000109:Acetylcholine; C035739:Quin2; D002118:Calcium