title: Bimodal regulation of secretion by cytoplasmic Ca2+ as demonstrated by the parathyroid.
abstract: Bovine parathyroid cells were used to study parathyroid hormone (PTH) release and the cytoplasmic Ca2+ concentration (Cai2+). When the extracellular Ca2+ concentration was decreased from 3.0 to 0.5 mM, perifused cells reacted with rapid stimulation of PTH release. However, a further reduction of extracellular Ca2+ to less than 10 nM resulted in prompt inhibition. Both effects were readily reversible. Using the intracellular Ca2+ indicator quin-2 also as a buffer for calcium it was possible to control Cai2+ within the 20-600 nM range. PTH release was found to increase with Cai2+ up to 200 nM but was gradually suppressed above this concentration.
mesh_terms: D000634:Aminoquinolines; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D000242:Cyclic AMP / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D006706:Homeostasis; D010280:Parathyroid Glands / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism
chemical_list: D000634:Aminoquinolines; D010281:Parathyroid Hormone; D010743:Phospholipids; D004533:Egtazic Acid; D000242:Cyclic AMP; D011494:Protein Kinases; C035739:Quin2; D002118:Calcium