RESUMO
The effects of gossypol-acetic acid (a male contraceptive) on transmembrane fluxes of sodium and potassium in human red cells were studied, in comparison with the effects of ouabain (an inhibitor of Na+-K+-ATPase) and furosemide (an inhibitor of Na+, K+ cotransport). It was found that gossypol may be an inhibitor of outward (Na+, K+) cotransport in human red cells but has no significant effect on (Na+, K+)-ATPase. The results provide new evidence for elucidating the mechanism of hypokalemia caused by gossypol.
Assuntos
Membrana Eritrocítica/metabolismo , Gossipol/análogos & derivados , Potássio/farmacocinética , Sódio/farmacocinética , Gossipol/farmacologia , HumanosAssuntos
Cardiomiopatias/enzimologia , Mitocôndrias Cardíacas/enzimologia , Selênio/deficiência , Adenosina Trifosfatases/análise , Cálcio/análise , Cardiomiopatias/metabolismo , Cardiomiopatias/patologia , Complexo IV da Cadeia de Transporte de Elétrons/análise , Humanos , Fluidez de Membrana , Mitocôndrias Cardíacas/análise , Succinato Desidrogenase/análiseRESUMO
Na2SeO3 supplementation in the ageing medium could protect aged erythrocyte ghosts from decreases in lipid fluidity, Na, K-ATPase activity, and sensitivity to ouabain. Results also showed that Se could obviously prevent the dissociation of spectrin from the erythrocyte membrane. Furthermore, Se could markedly promote the reassociation of spectrin with the spectrin-stripped inside out membrane vesicles(IOVs) of erythrocytes. The protective action of Se on biomembranes is generally interpreted in terms of the activity of Se-containing glutathione peroxidase (GSHPx). However, since GSHPx is mainly distributed in the cytoplasm of erythrocytes, the stabilizing effect of Se on erythrocyte membranes might not be related to the activity of this enzyme.
Assuntos
Envelhecimento Eritrocítico/efeitos dos fármacos , Membrana Eritrocítica/efeitos dos fármacos , Selênio/farmacologia , Membrana Eritrocítica/enzimologia , Membrana Eritrocítica/ultraestrutura , Humanos , Cinética , Fluidez de Membrana/efeitos dos fármacos , Ouabaína/farmacologia , Ácido Selenioso , ATPase Trocadora de Sódio-Potássio/sangueRESUMO
During the ageing of erythrocyte membrane, the spectrin content, Na,K-ATPase activity as well as the lipid fluidity are obviously decreased. However, supplementation of a trace amount of Na2SeO3 in the medium could prevent the dissociation of spectrin from membrane and delay the changes of Na,K-ATPase activity and lipid fluidity. The effectiveness is proportional to Se concentration within the range of 0.1-1.0 ppm. Similar effect of supplementation of Se on the intact erythrocytes during ageing has been also observed. The protective action of Se on biomembranes is generally interpreted in terms of the activity of Se-containing glutathione peroxidase (GSHPx). However, GSHPx mainly distributes in the cytoplasma of erythrocytes, therefore it seems that the protective action of supplemented Se on the isolated erythrocyte membrane might not be related to the activity of GSHPx.
Assuntos
Envelhecimento Eritrocítico/efeitos dos fármacos , Membrana Eritrocítica/efeitos dos fármacos , Compostos de Selênio , Selênio/farmacologia , Membrana Eritrocítica/enzimologia , Humanos , Fluidez de Membrana/efeitos dos fármacos , Óxidos de Selênio , ATPase Trocadora de Sódio-Potássio/metabolismoRESUMO
The content of binding-Se in erythrocyte membrane may affect its structure and function. Decrease in Se content will lead to a lower activity of Na, K-ATPase and lipid fluidity in ghosts, and a marked increase in Na, K-ATPase activity as well as lipid fluidity of erythrocyte membrane was observed by supplementation of low concentration of Na2SeO3 (0.03-0.3 ppm Se), in vitro. This effect was obvious only when the ghosts were incubated with Se at 0-4 degrees C for at least half an hour prior to assay.
