Activation of potassium channels in erythrocytes of marine teleost Scorpaena porcus.
To assess the possibility of stimulating Ca2+-activated K+ channels, marine fish erythrocytes were incubated at 20-22 degrees C in saline containing a Ca2+-ATPase inhibitor (orthovanadate), a Ca2+ ionophore (A23187), propranolol or Pb2+. Incubation of the cells for up to 2 h under control conditions or in the presence of 5 mM NH4VO3 and 1 mM Ca2+ did not affect the intracellular K+ and Na+ concentrations. About 50% cellular K+ was lost from erythrocytes incubated in the presence of 0.01 mM A23187, 1 mM EGTA and 0.4-1.0 mM Ca2+. There was a significant loss of cellular K+ after the addition of 0.05-0.2 mM propranolol to the incubation medium. The stimulatory effect of propranolol on the K+ efflux was independent of external Ca2+. Blockers of Ca2+ transport, verapamil and Co2+, caused only a small decrease in the K+ loss induced by propranolol. The treatment of erythrocytes with 1-2 microM Pb2+ led to a minor K+ loss, but at a Pb2+ concentration of 20-50 microM, about 70% cellular K+ was lost. The K+ efflux induced by propranolol or Pb2+ was completely blocked by 1 mM quinine. The induced K+ loss from the erythrocytes was accompanied by a slight increase in the intracellular Na+ concentration. These data indicate the possibility of inducing Ca2+- and Pb2+-activated potassium channels in erythrocytes of S. porcus. A distinctive feature of the cells is a high sensitivity to propranolol, which activates K+ channels in the absence of external Ca2+.
Silkin
Y A
YA
Karadag Natural Reserve, Ukrainian Academy of Sciences, Feodosia, Crimean Region.
Silkina
E N
EN
Sherstobitov
A O
AO
Gusev
G P
GP
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism*; D005399:Fishes / Q000097:blood*; D006801:Humans; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D007476:Ionophores / Q000494:pharmacology; D007854:Lead / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000097:blood*; D011433:Propranolol / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism; D014638:Vanadates / Q000494:pharmacology
D007476:Ionophores; D015221:Potassium Channels; D007854:Lead; D000001:Calcimycin; D014638:Vanadates; D012964:Sodium; D011433:Propranolol; D011188:Potassium