Manipulation of intracellular calcium in NCB-20 cells.
A number of lines of evidence indicate that the Ca2+ and cyclic AMP signalling systems interact in NCB-20 cells. However, to date, the regulation of [Ca2+]i homeostasis has not been studied in this cell line. The present study aimed to clarify our understanding of [Ca2+]i homeostasis in these cells and to evaluate tools that manipulate [Ca2+]i, independently of protein kinase C effects. Bradykinin, by a B2-receptor, elevated [Ca2+]i by a pertussis-toxin-insensitive mechanism. The BK-stimulated [Ca2+]i rise originated from intracellular sources, without a contribution from Ca2+ entry mechanisms. The effect of BK was precluded by pretreatment with thapsigargin and ionomycin--compounds that elevated [Ca2+]i independent of phospholipase C activation. Both compounds, however, exerted effects in addition to stimulating release of Ca2+ from BK-sensitive stores; the BK-sensitive Ca2+ pool was a subset of the thapsigargin-sensitive pool; ionomycin strongly stimulates Ca2+ entry. Activation of protein kinases A and C attenuated the duration of the BK-induced rise in [Ca2+]i, without affecting the peak [Ca2+]i, suggesting interference with the BK response at a step downstream of the activation of phospholipase C. Application of these approaches should enhance the delineation of the consequences of Ca2+ mobilization on cyclic AMP accumulation.
Garritsen
A
A
Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80262.
Cooper
D M
DM
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002460:Cell Line; D004789:Enzyme Activation; D006822:Hybrid Cells / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism*; D015759:Ionomycin / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
D013729:Terpenes; D015759:Ionomycin; D019284:Thapsigargin; D011494:Protein Kinases; D011493:Protein Kinase C; D000252:Calcium-Transporting ATPases; D001920:Bradykinin; D002118:Calcium