Role of intra- and extracellular calcium stores in mesothelial cell response to histamine.
Ca2+ may play an important role in mesothelial cellular responses because Ca2+ acts as an intracellular messenger in a wide variety of cellular responses in different tissues. The present study was designed to clarify the mechanisms of cytosolic Ca2+ mobilization in the mesothelial cells. Rat pleural and pericardial mesothelial cells were maintained in vitro, and the Ca2+ movement was evaluated using fura 2. Histamine (30 microM to 10 mM) induced a biphasic elevation of intracellular levels of Ca2+ concentration ([Ca2+]i) that consisted of a rapid initial transient elevation followed by a sustained elevation. Neither removal of extracellular Ca2+ nor inhibition of Ca2+ influx by 1 microM nifedipine affected the histamine-induced initial transient elevation of [Ca2+]i in mesothelial cells. Nifedipine did not block histamine-induced sustained elevation of [Ca2+]i. KCl (25 and 50 mM) elicited a biphasic elevation of [Ca2+]i. However, this KCl-induced elevation of [Ca2+]i was abolished by nifedipine treatment. Ryanodine (10 microM) induced a transient elevation of [Ca2+]i in Ca(2+)-free solution. The histamine-induced elevation of [Ca2+]i was completely blocked by H1-receptor antagonists. These results suggest that the mesothelial cells have three pathways to increase [Ca2+]i: release from intracellular Ca2+ stores, Ca2+ influx through L-type voltage-dependent Ca2+ channels, and receptor-operated Ca2+ channels.
Department of Comparative Pathophysiology, Faculty of Agriculture, University of Tokyo, Japan.
K
K
Ito
M
M
Kuwahara
S
S
Sugano
M
M
Kuwahara
D000199:Actins / Q000502:physiology; D000818:Animals; D015220:Calcium Channels / Q000502:physiology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000648:ultrastructure; D004594:Electrophysiology; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism*; D006632:Histamine / Q000494:pharmacology; D007425:Intracellular Membranes / Q000378:metabolism*; D010496:Pericardium / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D010994:Pleura / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY; D011969:Receptors, Histamine H1 / Q000378:metabolism; D011970:Receptors, Histamine H2 / Q000378:metabolism
D000199:Actins; D015220:Calcium Channels; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D006632:Histamine