EFFECT OF LATRUNCULIN B, JASPLAKINOLIDE AND BREFELDIN A ON THE STORE-DEPENDENT Ca2+ ENTRY IN
MACROPHAGES
L. S. Kurilova, Z. I. Krutetskaya, O. E. Lebedev
Chair of Biophysics, St. Petersburg State University;
e-mail: cozzy@mail.ru
Using Fura-2AM microfluorimetry, effect of actin filament modifiers and vesicular trafficking inhibitor on the
store-dependent Ca2+ entry induced by purinergic agonists (ATP, UTP) and endoplasmic
Ca2+-ATPase inhibitors (thapsigargin, cyclopiazonic acid) in rat peritoneal macrophages was investigated.
It was shown that inhibition of actin polymerization by latrunculin B had a biphasic time-dependent effect on
Ca2+ entry, showing an initial potentiation followed by inhibition of Ca2+ entry. Moreover,
addition of latrunculin B after induction of store-dependent Ca2+ entry inhibited the Ca2+ influx.
Jasplakinolide, which reorganizes actin filaments into a tight cortical layer adjacent to the plasma membrane,
prevented activation of store-dependent Ca2+ entry but did not modify this process after its activation.
Vesicular transport inhibitor brefeldin A, which inactivates arf proteins, inhibited activation of store-dependent
Ca2+ entry but did not alter this mechanism once being initiated. These data are compatible with the
sectretion-like coupling model for store-dependent Ca2+ entry in macrophages based on a reversible
trafficking and coupling of Ca2+ store with the plasma membrane.
Key words: peritoneal macrophages, store-dependent Ca2+ entry, microfilaments, vesicular
transport inhibitor brefeldin A
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