STRUCTURE AND FUNCTION OF THE BAND 3 CL~-/HCO_3~- TRANSPORTER IN CHRONIC RESPIRATORY FAILURE PATIENTS

摘要

Objective. To study red blood cell (RBC) membrane band 3 protein structure and anion transport function in cor pulmonale patients with respiratory failure. Patients and Methods. Blood samples were obtained from 80 cases of cor pulmonale and 37 normal subjects (control group). The patients were divided into type Ⅰ respiratory failure (Group Ⅰ, n = 40) and type Ⅱ respiratory failure (Group Ⅱ, n = 40). The anion permeability of the erythrocyte membrane (Pcl), PO_2 and PCO_2 in 12 of the patients with type Ⅱ respiratory failure were observed in acute stage (AS), chronic stage (CS) and recovery stage (RS). Membrane protein was analyzed by polyacrylamide electrophoresis in SDS. 55-KDa membrane domain was fractionated on 10% NaDodSO4 polyacrylamide gel column and purified further with a sephadax G-25 column. The composition of amino acids was analyzed on a Beckman 6300 Gold system amino acid analyzer. The Pcl was determined by the hypoisotonic hemolysis method. Results. The relative content of band 3 protein erythrocytic membrane, anion permeability coefficient of the erythrocyte membrane and plasma chloride in the patients with cor pulmonale with type Ⅱ respiratory failure were significantly lower than those in the patients with type Ⅰ respiratory failure and the control. The number of residues in the anion transport domain of the trypsin fragment of 55 000 daltons of band 3 protein showed no significant difference among the three groups. Conclusions. The structure of anion transport sites remains intact and so the reduction of the anion transport function of band 3 protein in patients with cor pulmonale with type Ⅱ respiratory failure may be due to the decrease of the relative content of band 3 protein, the decrease of extraerythrocytic chloride and hypoxia.