Effect of protein kinase C activation on Na+-H+ exchange in erythrocytes of frog Rana temporaria.
The treatment of frog erythrocytes incubated in standard nitrate medium with 100 nM phorbol ester (PMA) induced a sharp increase in the 22Na uptake by the cells and intracellular Na(+) concentration. The PMA-induced enhancement in 22Na uptake was stimulated by the addition of 0.1 mM ouabain to the incubation medium and completely blocked by 1 mM amiloride. The time course of 22Na uptake by frog red cells in the presence of PMA showed a lag phase ( approximately 5 min), after which was linear within 5-15 min. The calculated Na(+) influx in erythrocytes treated with PMA was 49.4+/-3.7 mmol l(-1) cells h(-1) as compared with 1.2+/-0.25 mmol l(-1) h(-1) for control cells. 5-(N-ethyl-N-isopropyl)-amiloride, selective blocker of NHE1, caused a dose-dependent inhibition of the PMA-induced Na(+) influx with IC(50) of 0.27 microM. The PMA-induced Na(+) influx was almost completely inhibited by 0.1 microM staurosporine, protein kinase C blocker. Pretreatment of frog red blood cells for 5, 10 or 15 min with 10 mM NaF, non-selective inhibitor of protein phosphatase, led to a progressive stimulation of the PMA effect on Na(+) influx. Both amiloride and NaF did not affect the basal Na(+) influx in frog erythrocytes. The data indicate that the Na(+)-H(+) exchanger in the frog erythrocytes is quiescent under basal conditions and can be markedly stimulated by PMA.
Agalakova
Natalia I
NI
Laboratory of Comparative Biochemistry of Inorganic ions, Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St Petersburg, Russia.
Gusev
Gennadii P
GP
D000584:Amiloride / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002273:Carcinogens / Q000494:pharmacology; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004912:Erythrocytes / Q000201:enzymology*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011896:Rana temporaria; D012964:Sodium / Q000378:metabolism; D012969:Sodium Fluoride / Q000494:pharmacology; D012979:Sodium Radioisotopes; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000889:Anti-Arrhythmia Agents; D002273:Carcinogens; D004791:Enzyme Inhibitors; D012979:Sodium Radioisotopes; D017923:Sodium-Hydrogen Exchangers; D000584:Amiloride; D012969:Sodium Fluoride; D012964:Sodium; D011493:Protein Kinase C; D010749:Phosphoprotein Phosphatases; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; C039614:ethylisopropylamiloride