[Activation of specific membrane mechanisms in the myocardium cells on early stages of ischemia].
Electron probe microanalysis was employed to determine the elemental concentration (K,Na,Cl) in a myocyte on cryosections of the papillary muscle of the isolated rat (Wistar) heart. Protocols of global ischemia and ischemic conditions under glucose-free anoxic perfusion were applied. It was shown that global ischemia induces potassium deficiency (94 +/- 2 mM) in the myocyte and an increase in the level of sodium (72 +/- 4 mM) and chlorine (42 +/- 1 mM) in the cytoplasm compared with intact cell (122 +/- 2; 36 +/- 1; 24 +/- 1 mM). Glucose-free anoxic perfusion leads to a smooth fall of potassium concentration in the cell up to 54 +/- 2 mM with the retention of intracellular sodium (40 +/- 1 mM) and chlorine (26 +/- 1 mM) level. The present finding suggest that, in early ischemia, specific membrane mechanisms of ion transport are activated. Among these are KNa channel, Hi(+)-Nao+ exchange, KATP channel, lactate transport from the cell, associated either with potassium efflux to the extracellular space or chlorine influx into the myocyte. It is assumed that Na/K-ATPase is also activated under ischemic conditions.
Pogorelov
A G
AG
Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia.
Pogorelova
V N
VN
Dubrovkin
M I
MI
Demin
I P
IP
Khrenova
E V
EV
D000818:Animals; D015687:Cell Hypoxia; D002462:Cell Membrane / Q000378:metabolism; D002713:Chlorine / Q000378:metabolism; D003080:Cold Temperature; D004577:Electron Probe Microanalysis; D005629:Frozen Sections; D005947:Glucose / Q000172:deficiency; D066298:In Vitro Techniques; D007511:Ischemia / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D010210:Papillary Muscles / Q000378:metabolism / Q000648:ultrastructure; D011188:Potassium / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism
D002713:Chlorine; D012964:Sodium; D005947:Glucose; D011188:Potassium