Entity

Time filter

Source Type


Koltsova S.V.,Center Hospitalier Of Luniversite Of Montreal Chum Technopole Angus | Akimova O.A.,Center Hospitalier Of Luniversite Of Montreal Chum Technopole Angus | Kotelevtsev S.V.,Moscow State University | Grygorczyk R.,Center Hospitalier Of Luniversite Of Montreal Chum Technopole Angus | And 2 more authors.
Canadian Journal of Physiology and Pharmacology | Year: 2012

In the present work, we compared the outcome of hyperosmotic and isosmotic shrinkage on ion transport and protein phosphorylation in C11-MDCK cells resembling intercalated cells from collecting ducts and in vascular smooth muscle cells (VSMC) from the rat aorta. Hyperosmotic shrinkage was triggered by cell exposure to hypertonic medium, whereas isosmotic shrinkage was evoked by cell transfer from an hypoosmotic to an isosmotic environment. Despite a similar cell volume decrease of 40%-50%, the consequences of hyperosmotic and isosmotic shrinkage on cellular functions were sharply different. In C11-MDCK and VSMC, hyperosmotic shrinkage completely inhibited Na +, K +-ATPase and Na +, P i cotransport. In contrast, in both types of cells isosmotic shrinkage slightly increased rather than suppressed Na +, K +-ATPase and did not change Na +, P i cotransport. In C11-MDCK cells, phosphorylation of JNK1/2 and Erk1/2 mitogen-activated protein kinases was augmented in hyperosmotically shrunken cells by ~7- and 2-fold, respectively, but was not affected in cells subjected to isosmotic shrinkage. These results demonstrate that the data obtained in cells subjected to hyperosmotic shrinkage cannot be considered as sufficient proof implicating cell volume perturbations in the regulation of cellular functions under isosmotic conditions.


Koltsova S.V.,Center Hospitalier Of Luniversite Of Montreal Chum Technopole Angus | Koltsova S.V.,Russian Academy of Medical Sciences | Trushina Y.A.,Moscow State University | Akimova O.A.,Center Hospitalier Of Luniversite Of Montreal Chum Technopole Angus | And 4 more authors.
Pathophysiology | Year: 2011

Numerous studies have demonstrated heightened Na+/Li+ countertransport (NLCT) activity in erythrocytes of patients with essential hypertension or diabetic nephropathy. The same carrier also contributes to the therapeutic action of lithium salt, widely used in the treatment of psychiatric disorders. However, the molecular origin of NLCT remains unknown. This study examined the role of major ion transporters in NLCT by comparative analysis of its activity and that of ion transporters providing inwardly directed 86Rb, 22Na and 32P fluxes. NLCT was below the detection limit in rat erythrocytes and ∼50-fold higher in rabbits compared to humans. Unlike NLCT, the activities of Na+,K+-ATPase, Na+,K+,2Cl- cotransporter and anion exchanger were somewhat similar in the erythrocytes of these species, whereas Na+,Pi cotransport was in 1:2:6 proportion in rats, humans and rabbits, respectively. Loading of erythrocytes with Li+ for NLCT measurement did not affect the activity of Na+,Pi cotransporter. Keeping in mind that NLCT is much higher in rabbits vs humans and rats, we compared the set of membrane proteins in these species using 2-dimensional gel electrophoresis. This approach revealed 174 common spots, whereas 132 proteins were detected only in human and rabbit erythrocyte membranes. Among these proteins, we found 17 spots whose expression was higher by more than 5-fold in rabbit compared to human erythrocytes. Thus, our results argue against the involvement of major ion transporters in NLCT. They also show that comparative proteomics is a potent tool to identify the molecular origin of this carrier. © 2011 Elsevier Ireland Ltd.

Discover hidden collaborations