Cytosolic Ca2+ and the regulation of secretion in parathyroid cells.
The concentration of intracellular Ca2+ [( Ca2+]i) was measured in dissociated bovine parathyroid cells loaded with quin-2 or fura-2. In quin-2-loaded cells, increases in the concentration of extracellular Ca2+ elicited slow, monophasic increases in [Ca2+]i, whereas in fura-2-loaded cells, extracellular Ca2+ evoked rapid, transient increases which were followed by lower, yet sustained increases in [Ca2+]i. Cytosolic Ca2+ transients arose from the mobilization of cellular Ca2+ and could be evoked by a variety of divalent cations. Transient, but not sustained increases in [Ca2+]i were associated with an inhibition of hormone secretion. Secretion was still inhibited, however, when cytosolic Ca2+ transients were blocked by buffering with quin-2, suggesting that changes in [Ca2+]i might not be the essential factor regulating secretion in parathyroid cells.
D000634:Aminoquinolines; D000818:Animals; D001572:Benzofurans; D002118:Calcium / Q000502:physiology*; D002417:Cattle; D003600:Cytosol / Q000502:physiology; D016257:Fura-2; D007811:Lanthanum / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D010280:Parathyroid Glands / Q000378:metabolism*; D012636:Secretory Rate / Q000187:drug effects
D000634:Aminoquinolines; D001572:Benzofurans; D007811:Lanthanum; C035738:Quin2-acetoxymethyl ester; D008274:Magnesium; D002118:Calcium; D016257:Fura-2