ERYTHROCYTE PASSIVE POTASSIUM FLUX IS INCREASED IN PATIENTS WITH ISCHEMIC CORONARY-DISEASE (ICD) AND IN SUBJECTS WITH FAMILY HISTORY OF ICD

Background. It has been proposed that ischemic coronary disease (ICD) associated potassium loss could be due to modifications of potassium p ermeability. We investigated whether a positive family history of ICD can influence this parameter. We have compared potassium permeability in erythrocytes from ICD patients and from positive family history sub jects (FICD) with control subjects. Methods. All patients and subjects were carefully selected for the absence of hypertension and dysmetabo lic pathologies. ICD group: 24 patients (19 males, 5 females; ages 43 to 69) all affected by ischemic coronary disease, under no drug treatm ent; FICD group: 18 subjects (all males, ages 27 to 42) with a verifie d positive ICD family history, without hypertensive family history and cardiovascular pathology; control group: 16 subjects (11 males, 5 fem ales; ages 28 to 48) without positive family history of ICD. Passive p otassium efflux (PPE) was spectrophotometrically measured in K-free me dium containing ouabain and bumetanide. The kinetic constant was calcu lated by dividing PPE by the erythrocyte potassium concentration. Resu lts. No statistically significant differences were noted between the i ntracellular potassium content of the three groups. However, (1) the p assive potassium permeability of the ICD group was significantly highe r (kK=0.055 +/- 0.021 h(-1), n = 24) than that of the control group (k K = 0.023 +/- 0.008 h(-1), n = 16; p<0.00001), (2) the FICD group was higher (kK=0.036 +/- 0.012 h(-1), n = 18) than the control group (p<0. 001), and (3) the ICD group was higher than the FICD group (p<0.001). Conclusions. Our results suggest an inheritability of ICD, paralleling the familial aggregation of the pathology. Erythrocyte potassium perm eability could represent an early marker of ischemic coronary disease and be used as a prophylactic tool.