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 permeability. 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 subjects (FICD) with control subjects. METHODS: All patients and subjects were carefully selected for the absence of hypertension and dysmetabolic pathologies. ICD group: 24 patients (19 males, 5 females; ages 43 to 69) all affected by ischemic coronary disease, under no drug treatment; FICD group: 18 subjects (all males, ages 27 to 42) with a verified positive ICD family history, without hypertensive family history and cardiovascular pathology; control group: 16 subjects (11 males, 5 females; ages 28 to 48) without positive family history of ICD. Passive potassium efflux (PPE) was spectrophotometrically measured in K-free medium containing ouabain and bumetanide. The kinetic constant was calculated by dividing PPE by the erythrocyte potassium concentration. RESULTS: No statistically significant differences were noted between the intracellular potassium content of the three groups. However, (1) the passive potassium permeability of the ICD group was significantly higher (kK=0.055 +/- 0.021 h(-1), n=24) than that of the control group (kK=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 permeability could represent an early marker of ischemic coronary disease and be used as a prophylactic tool.