[Thapsigargin-sensitive and insensitive intracellular calcium stores in acinar cells of the submandibular salivary gland in rats].
Acinar cells of rat submandibular salivary gland are characterized by heterogeneity of intracellular Ca2+ stores. In the present work we have studied this heterogeneity using Arsenazo III dye to measure a cellular total calcium content and Fura-2/AM, to determine free cytosolic calcium concentration ([Ca2+]i). We have found that the amount of Ca2+ released by inhibition of Ca2+ ATPase of the ER with thapsigargin comprises approximately 30% of total ER calcium. This result was obtained in experiments on both intact and permeabilized acinar cells. We have also shown that both Ca2+ ATPase inhibition with thapsigargin and emptying the stores with acetylcholine (ACh) led to activation of store-operated Ca2+ influx (an increase in total calcium content of approximately 14%). In permeabilized cells application of ACh after preincubation with thapsigargin led to a further decrease in total cellular calcium content (approximately 38%). At the same time in intact cells it resulted in generation of [Ca2+]i transients with gradually decreasing amplitudes. Thus, ACh is capable of producing an additional release of Ca2+ from thapsigargin-insensitive stores. This additional release is IP3-dependent since it was completely blocked by heparin. We conclude that in acinar cells of rat submandibular gland thapsigargin-sensitive and thapsigargin-insensitive Ca2+ stores could exist.
Kopach
O V
OV
Kruhlykov
I A
IA
Voĭtenko
N V
NV
Fedirko
N V
NV
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013363:Submandibular Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases; D000109:Acetylcholine; D002118:Calcium