特异性单克隆抗体对地高辛抑制家兔红细胞膜Na~+,K~+-ATP酶活性的拮抗作用

本文研究结果表明抗地高辛特异性MAb可有效地拮抗地高辛引起的RRBC膜Na~+,K~+-ATP酶活性抑制。1.8×10~4倍稀释的FD8 MAb腹水,在试管内可使4ng/ml浓度地高辛引起的酶活性抑制恢复达50％。给地高辛中毒兔iv FD8 MAb 腹水后,被抑制的RRBC膜Na~+,K~+-ATP酶活性迅速恢复,酶抑制造成的RRBC内Na~+,K~+浓度异常也随之得到恢复。本研究从受体水平证实了特异性MAb解除地高辛毒性的作用机理

Antagonism to digoxin-induced inhibition of rabbit erythrocyte Na~+ ,K~+ -ATPase by specific monoclonal antibody

A study on the interaction among digoxin, specific anti-digoxin monoclonal antibody (MAb) and Na+,K+-ATPase was performed with rabbit red blood cell (RRBC) membrane. In vitro experiment with pooled RRBC membrane preparation showed that the Na+, K+-ATPase activity was highly sensitive to digoxin and the IC50 was 95.4pM in our testing system. This inhibition was effectively antagonized by the specific anti-digoxin MAb FD8 (immunoglobulin subclass IgGl, affinity to digoxin hapten being 4.05×108M-1). MAb FD8 ascites of 1.8×104 fold dilution could lead to 50% recovery of the Na+,K+-ATPase activity inhibited by digoxin of 4 ng/ml concentration. After transfusion of MAb FD8 ascites to rabbits which had been given digoxin 1 mg/kg intravenously, the advanced inhibition of RRBC membrane Na+,K+-ATPase was soon recoveredand the degree of recovery was related to the dose of MAb given. The increase of intracellular Na+ concentration and decrease of intracellular K+ concentration caused by Na+,K+ -ATPase inhibition were also returned to about normal after venoclysis of MAb FD8. Results of radioimmu-noassay showed that the amount of free digoxin in the plasma of those rabbits was significantly reduced by MAb treatment. This work indicates that specific anti-digoxin MAb is a highly effective antagonist to digoxin and also suggests that the antidigoxin MAb's of high affinity combat with digoxin toxic ity by enhancing dissociation of digoxin -Na+,K+-ATPase complex.