[Activation of Na/H exchange by thrombin in peritoneal mast cells].
Using the fluorescent probe, BCECF, the changes in intracellular pH (pHi) in rat peritoneal mast cells were studied. alpha-Thrombin (0.1 nM) induced biphasic changes in pHi which consisted in a temporary decrease in pH with its subsequent steady increase due to the Na/H exchange activation which was inhibited by EIPA and controlled by extracellular Na+. The biphasic changes in pHi induced by DIP-alpha-thrombin (0.1 pM-1 nM), a catalytically inactive form with an intact recognition site, were similar to those of alpha-thrombin, whereas beta/gamma-thrombin (10-1000 pM), a catalytically active form characterized by structural disturbances in the recognition site, was able to induce only the initial phase of acidification. The thrombin recognition site modulators, alpha 1-thymosin and heparin, blocked the ability of the enzyme to induce the alkalinization of pHi. Nigericin stimulated the Na/H-exchange in mast cells. The rate of the Na/H-exchange activation determined with nigericin, decreased with an increase in the alpha-thrombin dose from 0.1 pM up to 10 nM. Activation of protein kinase C (PKC) in mast cells by PMA used at 1 nM and 10 nM led to the alkalinization of the cytoplasm as a result of the Na/H-exchange activation blocked by EIPA. The PKC inhibitor, H-7, suppressed the pHi increase induced by both PMA and alpha-thrombin. The alpha-thrombin-induced acidification of the cytoplasm was completely blocked by SITS in Ca(2+)-free media, whereas in media with Ca2+ SITS inhibited the pHi decline. Acidification of the cytoplasm by thrombin seems to be due to both Ca2+ influx and activation of Cl- fluxes. It is concluded that the observed activation of the Na/H-exchange by thrombin is induced by a cascade of intracellular reactions involving PKC.
Strukova
S M
SM
Khlagatian
S V
SV
Pinelis
V G
VG
Dugina
T N
TN
Kudinov
Iu V
IuV
Berzhets
V M
VM
Markov
Kh M
KhM
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D004789:Enzyme Activation; D005452:Fluoresceins; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007546:Isoquinolines / Q000494:pharmacology; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism*; D009550:Nigericin / Q000494:pharmacology; D010529:Peritoneal Cavity / Q000166:cytology; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D012964:Sodium / Q000378:metabolism*; D013917:Thrombin / Q000494:pharmacology*
D005452:Fluoresceins; D007546:Isoquinolines; D010879:Piperazines; D006859:Hydrogen; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D012964:Sodium; D011493:Protein Kinase C; D013917:Thrombin; D009550:Nigericin
Aktivatsiia trombinom Na/H obmena v peritoneal'nykh tuchnykh kletkakh.