An increase in intracellular concentration of free Ca 2+ ([ Ca 2+ ] i ) in the cytoplasm of different cell types is responsible for may pivotal processes, such as triggering proliferation, contractility, secretion, and other types of physiological activity [1,2]. Calcium ions enter the cytoplasm from extracellular matrix and intracellular Ca 2+ stores. Due to initially low permeability of plasma membranes for Ca 2+ and active Ca 2+ uptake against electrochemical gradient, which is mediated by Ca 2+ -ATPases contained in plasma membranes and membranes of intracellular Ca 2+ stores, [ Ca 2+ ] i is maintained at low levels. The reversible Na + -Ca 2+ -exchanger, responsible for passive Ca 2+ transfer, also plays an important role in the regulation of [ Ca 2+ ] i [3]. Plasma membranes of electrically nonexcitable cells contain several types of Ca 2+ -channels differing in structure and mechanisms of regulation of their activity. The latter include the receptor-operated Ca 2+ -channels (ROCs), secondary messenger-operated Ca 2+ -channels (SMOCs), and intracellular store-operated Ca 2+ -channels (SOCs) [4]. Ca 2+ -channels of the last type have been studied the most intensively; these are ubiquitous channels that are present even in nonexcitable cells, where they are predominant [5]. Store-operated Ca 2+ -channels open when Ca 2+ level in the lumens of intracellular Ca 2+ stores drop, which results from Ca 2+ release from the stores to the cytoplasm through Ca 2+ -channels. The latter are components of the receptor for inositol 1,4,5-trisphosphate (Ins P 3 ) [2][3][4][5]. The depletion of Ca 2+ stores is accompanied by a change in the conformation of the Ins P 3 receptor; according to current notion, the latter physically contacts with SOC proteins, thereby facilitating their activation [6].Thiols are among the most widespread and reactive compounds in all biological systems. Modification of cellular thiols with disulfides was accompanied by changes in physiological activity and suppression of cell division [7,8]. Diallyl disulfide (DADS), the main liposoluble component of the garlic, is classified with natural organic disulfides [9]. A great interest of researchers to DADS is determined by its ability to effectively suppress proliferation of human tumor cells [10,11]. The anticarcinogenic effect of DADS is apparently based on the induction of apoptosis, related to an increase in [ Ca 2+ ] i , ç 2 é 2 production, and activation of caspase 3 [11].The goal of this work was to study the effect of DADS on [ Ca 2+ ] i in human leucosis promyelocytes (HL-60 cells).
MATERIALS AND METHODSThapsigargin, ionomycin, digitonin, EGTA, Fura-2/AM, ATP, and DMSO were obtained from Sigma (United States).Diallyl disulfide (DADS) was isolated from garlic homogenate by extraction with CO 2 in a supercritical state at high temperatures. Extraction was performed at a pressure of 250 atm at 90 ° C for 30 min. DADS was separated from other sulfur-containing components using preparative gas chromatography on a PAKhV-08 chromatograph. Separation...
