An implication of novel methodology to study pancreatic acinar mitochondria under in situ conditions.

Mitochondria maintain numerous energy-consuming processes in pancreatic acinar cells, yet characteristics of pancreatic mitochondrial oxidative phosphorylation in native conditions are poorly studied. Besides, it is not known which type of solution is most adequate to preserve functions of pancreatic mitochondria in situ. Here we propose a novel experimental protocol suitable for in situ analysis of pancreatic mitochondria metabolic states.

Genes expression of calcium signaling molecules in salivary glands of Drosophila melanogaster larvae.

Genes expression of the Itp-r-83A, Ca-P60A, olf186-F which encode inositol-1,4,5-trisphosphate receptor, endoplasmic reticulum Ca(2+)-ATPase and Oral protein--component of the store-operated Ca(2+)-entry respectively, was determined in salivary glands of Drosophila melanogaster larvae. For this purpose, the method of reverse transcription-polymerase chain reaction (RT-PCR) was used. Our results suggest that mentioned Ca(2+)-transport systems play an important role in maintaining of Ca(2+)-homeostasis in larval salivary glands of Drosophila melanogaster.

[Effect of temperature and monensin on the level of intracellular sodium and pH in perfused RIF-1 cultured cells].

The direct measurement of temperature in subcutaneously (sc) implanted tumors shows that the actual tumor temperature is by 3-4 degrees C lower than the normal body temperature. Thus, the temperatures usually used for tumor hyperthermia are in fact heating the sc-tumors from 33 to 37 degrees C. The temperature increase during the perfusion of radiation-induced fibrosarcoma (RIF-1) cells from 33 to 37 degrees C caused a reversible increase in intracellular 23Na ([Na+]i) NMR signal intensity by 50-60%.

[Kinetic characteristics of Ca2+, Mg2+-ATPases in cells of the submandibular salivary gland of rats].

Kinetic properties of Ca2+, Mg2+-ATPases membranes from acinar cells of rat submandibular salivary glands have been investigated. It was found that kinetics of ATP hydrolysis dependent on Ca2+, Mg2+-ATPases corresponds to the first-order reaction during first 2 min. It was found that the initial velocity of the reaction (V0), maximal amount of the reaction product (Pmax) and characteristic time of the reaction (T) comprised 1.

[Identification of Ca2+ release channels in salivary glands secretory cells of Chironomus plumosus L].

The presence of two types of well-characterised Ca2+ release channels, namely IP3-receptors (Ins(1,4,5)P3Rs) and ryanodine-receptors (RyRs), was detected in the salivary glands secretory cells of Chironomus plumosus L. For this aim different blockators and activators of these Ca2+ -transport systems were used. The conditions for permeabilization of these cells by saponine were experimentally chosen for their more intensive action.

[Cyclic nucleotide regulation of intracellular Ca2+ release in secretory cells of salivary glands of Chironomus plumosus larvae].

We investigate action of cAMP and cGMP on calcium content in tissue of salivary gland of Chironomus plumosus larvae L. using arsenaso III. In order to permeabilize cells we incubate it in medium with saponin (0.

[Effect of p-chloromercuribenzoic acid and dithiothreitol on the Ca(2+) content of salivary glands and their protein secretion].

It has been shown, less concentrations of p-chlormercuribenzoate (1 and 2.5 mM) increased Ca2+ content in gland tissue and thereby protein secretion level that may occurred mainly by suppression Ca(2+)-pump or/and stimulation of Na(+)-Ca(2+)-exchange (both in cell plasma membrane) through modulation of SH-groups which form part of their molecules. Higher PCMB concentrations markedly decreased Ca2+ content in gland tissue as well as protein secretion.

[Influence of eosin y and orthovanadate on the steady-state of Ca(+)2 entry into secretory cells of exocrine glands and their spontaneous secretion].

Ca(2+)-pump blocators in low concentrations (eozyn Y up to 5 mM and ortovanadate up to 40 mM) essentially increases of Ca2+ content in salivary gland of Chironomus plumosus larvae's and spontaneous protein secretion. It was shown that eozyn Y much more effectively suppresses of plasma membrane Ca(2+)-pump then ortovanadate. Eozyn Y and ortovanadate in higher concentrations essentially decrease of Ca2+ content in glands and spontaneous protein secretion.

[Effect of chlorpromazine on the Ca2+-transport system of secretory cell membrane in Chironomus plumosus L. larval salivary glands].

Effect of chlorpromasine (specific blocking agent of calmoduline) on Na(+)-Ca(2+)-exchanger functioning, Ca(2+)-pump and potential dependent Ca(2+)-channels in plasmatic membrane of isolated salivary glands in Chironomus plumosus L. larvae was investigated. Addition of chlorpromasine in different concentrations to the incubation medium with physiological Na+ and K+ concentration increased Ca2+ content in the gland tissue and secretion of general protein by gland cells.

[The demonstration of steady-state Ca2+ influx into the cells of the salivary glands in Chironomus plumosus L. larvae and its role in basal secretion].

Ca2+ content in Chironomus plumosus salivary gland tissue we determined using Ca(2+)-sensitive dye arsenazo III and protein concentration in medium--by Lowry method. It was showed correlation between increasing of Ca2+ content in gland and basal secretion. So, basal secretion is Ca(2+)-dependent process.

[The modification of potential-dependent calcium channels in the membrane of secretory cells in a calcium-free medium].

Effect of modification of potential-dependent calcium channels in cells of the upper lobe of the salivary gland in Chironomus larva has been ascertained in the Ca-free medium containing Ca-binding substances (EGTA or EDTA). It is shown that the inward current depends on the sodium transmembrane gradient. The amplitude of the inward sodium current decreases under the influence of verapamil as well as with an increase of external concentration of Ca2+ ions.

[Characteristics of potential-dependent calcium channel current of the secretory cell membrane].

The parameters of inward current of potential-dependent calcium channels in cells of the upper and lower lobes of the salivary glands in Chironomus larvae have been studied. The current activation thresholds in cells of both types are near -60 mV, but in cells of the upper lobe the current reaches its maximum values at -20 mV, while in cells of the lower lobe at -10 mV. The current density in cells of the upper lobe is approximately 1.

[The identification and properties of chloride potential-dependent channels in the membrane of secretory cells].

Outward current of the salivary gland cells membrane of chironomus larva activated by the displacement of the membrane potential to the region of positive values has been registered by the voltage-clamp method under conditions of intracellular dialysis in the presence of the chloride transmembrane gradient. Activation threshold of the current is about +20 mV. Subsequent displacement of the membrane potential to the region of positive values causes an increase of the current.

[The demonstration of potential-dependent potassium channels in the plasma membrane of secretory cells].

Outward current of the salivary gland cells membrane of chironomus larva activated by the displacement of the membrane potential to the region of positive values has been registered by the voltage-clamp method under conditions of intracellular dialysis in the presence of only the potassium transmembrane gradient. Activation threshold of the current is about +10 mV. Subsequent displacement of the membrane potential to the region of positive values causes an increase of the current.

[Identification of depolarization-activated calcium flow in the secretory cell membrane].

The inward depolarization-activated current of the salivary gland cell membrane of the chironomus larva has been registered by the voltage-clamp method under conditions of the intracellular dialysis in the presence of the calcium transmembrane gradient only. An activation threshold of the current is about -50 mV, the current maximum is under -10 mV, reversion up to +10 mV leads to the current reduction. An increase in the extracellular Ca2+ concentration causes current amplification; the current decreases under the influence of verapamil, chlorpromazine, Mn2+ and Co2+.

[Effect of protein-modifying factors on sodium and potassium leakage currents of the secretory cell membranes].

Potassium and sodium leakage currents decrease when pH of the surroundings is lowering. Dicyclohexylcarbodiimide, a specific reagent of the COOH-groups does not change leakage currents. Trypsin, chymotrypsin, papain and pronase increase the sodium leakage current, not altering the potassium one.