Platelets and parotid acinar cells have different mechanisms for agonist-stimulated divalent cation entry.
Stimulation of platelets with thrombin or parotid acinar cells with carbachol results in an increase in [Ca2+]i which is due to both release from internal stores and influx across the plasma membrane. In platelets, thrombin also stimulates Mn2+ entry into the cytosol; this is seen as a stimulated quench of fura-2 fluorescence. In the parotid, however, carbachol does not stimulate Mn2+ entry. This result suggests different mechanisms of stimulated divalent cation entry in the two cell types and could have important implications in the study of receptor-mediated Ca2+ entry mechanisms.
Merritt
J E
JE
Department of Cellular Pharmacology, Smith, Kline and French Research Ltd., Welwyn, Herts, United Kingdom.
Hallam
T J
TJ
D000818:Animals; D001572:Benzofurans; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D002413:Cations, Divalent / Q000378:metabolism*; D016257:Fura-2; D006801:Humans; D008345:Manganese / Q000494:pharmacology; D010306:Parotid Gland / Q000187:drug effects* / Q000378:metabolism; D004369:Pentetic Acid / Q000494:pharmacology; D051381:Rats; D013917:Thrombin / Q000494:pharmacology
D001572:Benzofurans; D002413:Cations, Divalent; D008345:Manganese; D004369:Pentetic Acid; D002217:Carbachol; D013917:Thrombin; D002118:Calcium; D016257:Fura-2