Bipolar organic compound phloretin has a marked effect on transport and celular metabolism of glucose, uptake of non-metabolized glucose analogs and epithelial cell growth. We have studied effect of phloretin on Na+ and Rb+ uptake in rat alveolar epithelial type cells. Type cells were isolated by elastase digestion, purified by a differential adherential technique and than cultured on plastic in Dulbeccos medium with 10% fetal bovin serum. 22Na+ and 86Rb+ were used as trasers for Na+ and К+ accumulation in the presence or absence of phloretin (0–250 µM). The ATP content was determined by the adapted fireify luciferase assay.

Incubation of type cells with various concentration of phloretin leads to inhibition of Na and Rb uptake and a reduction of cellular ATP content. The effect is present in the presence and absence of external glucose and maximum inhibition was detected at a concentration of 250 µM. Sodium uptake was decreased from 46.0±2.7 in control up to 5.5+0.8 nmol/mg protein/5 min in the presence of 250 mM of phloretin and rubidium/potassium uptake was decreased from 35.3+2.8 to 1.8 nmol/mg protein /15 min. At the same concentration of drug cellular ATP content was reduced from 0 .9 6+ 0 .1 6 to 0 .0 3± 0 .0 2 nmol/mg protein. The results indicate that phloretin induces a reduction in cellular ATP content which lead to decrease in Na+ and К+ uptake in type 11 epithelial cells.