Bradykinin stimulates the intracellular calcium activity in human mesothelial cells

The aim of this study was to investigate the influence of bradykinin on the intracellular calcium activity ([Ca2+]i) in human mesothelial cells in culture.

Bradykinin (1-1000 nmol/l) caused a concentration-dependent and reversible increase of [Ca2+]i in mesothelial cells (n = 94); 10 nmol/l bradykinin increased [Ca2+]i from 23 +/- 9 to 670 +/- 170 nmol/l (n = 36). The pattern of the bradykinin-induced [Ca2+]i increase was biphasic with a transient [Ca2+]i peak, which was followed by a sustained [Ca2+]i plateau. The bradykinin-mediated [Ca2+]i plateau, but not the peak, was inhibited in a solution with an extracellular reduced Ca2+ concentration (from 1000 to 1 micromol/l, n = 11). Flufenamate (> or = 10 micromol/l), an inhibitor of non-selective ion channels abolished the bradykinin-mediated increase of [Ca2+], whereas the L-type Ca2+ channel blocker nicardipine (10 micromol/l) had no effect (n = 3-5). The [Ca2+]i response to bradykinin was inhibited by the BK2 antagonist Hoe 140 (IC50 +/- k7 nmol/l, n = 30).

The data indicate that bradykinin stimulates [Ca2+]i in mesothelial cells by a release of Ca2+ from intracellular stores and an influx from Ca2+ through non-selective channels via a BK2 receptor.