Modulation Influence of p-Chloromercuribenzoate on Plasma Membrane Na+-Ca2+Exchanger of the Secretory Cells of Chironomus Larvae Salivary Gland

Nv, Fedirko; MYu, Kievets; Vv, Man'ko

doi:10.1007/978-1-4615-0667-6_71

Cited by 2 publications

(1 citation statement)

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“…Sulfhydryl and carboxylic (SH and COOH) groups belong to the most important parts of calcium-transport molecules. In particular, it is known that active ("open") SH and COOH groups are localized in catalytic and regulatory centers of Са 2+ -ATPases [9][10][11][12][13] and sodium-calcium exchanger [14,15]. In addition, such active groups were found in the molecular structures of molecules of voltage-dependent, ryanodine-sensitive, and inositol trisphosphate calcium channels [16,17].…”

Section: Introductionmentioning

confidence: 99%

Role of Carboxylic Groups in the Control of Nonspecific Permeability of Mitochondrial Membranes

2010

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Ionized COOH groups are present in molecular structures involved in the process of formation of mitochondrial permeability transition pores (MPTPs), in particular, in the ADP/ATP antiporter and/or voltage-dependent anion channels. In experiments on preparations of isolated mitochondria obtained from rat hepatocytes, we found that, in the case of induction of nonspecific permeability through mitochondrial membranes under the action of Cа 2+ in a relatively low concentration (15 µM), modulation of the activity of COOH groups with the use of 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (1 mM) led to unidirectional effects, namely to acceleration of the processes of formation of MPTPs and transport of incubation solution and Са 2+ through these megachannels, prolongation of the open state of the latter, as well as to increases in the final volume (swelling) of the mitochondria and to a rise in the amount of Са 2+ released from these organelles. In contrast, when calcium was used in a high concentration (100 µM), the directions of the above processes were dissimilar. Slowing down of the flow of incubation solution through MPTPs and the process of their formation was observed; at the same time, Са 2+ release from the mitochondria was accelerated. However, the final volume of the mitochondria and the amount of Са 2+ released from these cellular structures increased. Differences between the effects of the used modulator of the activity of COOH groups on the nonspecific permeability of the mitochondria induced by calcium applied in low and high concentrations are perhaps determined by the following. The process of swelling of the mitochondria is saturable, while Са 2+ release from these organelles shows an unlimited pattern. The latter process (Са 2+ release) probably undergoes calcium-initiated inactivation. The mechanisms of induction of nonspecific permeability of the mitochondrial membranes under the action of low and high calcium concentrations differ from each other. The calcium uniporter in the mitochondria is sensitive to the modulator of the activity of COOH groups. Diffusion of water through the inner mitochondrial membrane and/or other systems provides some contribution to the studied processes; this can lead to changes in the transport of liquids in these organelles.

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