Beitrag zur Klinik, Pathophysiologie und Therapie des Bartter-Syndroms im Kindesalter*

Extra- and intracellular potassium concentration and prostaglandin production of skin fibroblasts grown from patients with Bartter's syndrome

In studies on human skin fibroblasts originating from three patients with Bartter's syndrome and in corresponding age and sex matched controls, the bradykinin stimulated release of PGE2, PGI2, PGF2 alpha and of arachidonic acid was examined. The studies were aimed at demonstrating the possible changes of prostaglandin production under the influence of changing extracellular potassium concentrations (0-12 mmol K/l) in the two study groups. Earlier studies were confirmed and extended by one more pair of fibroblast cultures, showing a decreased bradykinin stimulated PGE2 production in fibroblasts from patients with Bartter's syndrome as compared to control. The difference in bradykinin stimulated PGE2 production was significant, irrespective of the extracellular potassium concentrations, to which the cultures were exposed. The bradykinin stimulated PGE2 and PGF2 alpha-production by control fibroblasts was directly proportional to extracellular potassium concentrations, whereas the PG-production of Bartter's syndrome fibroblasts remained uninfluenced by extracellular potassium. Extra- and intracellular potassium concentrations were directly proportional and there was no difference in this relationship between controls and Bartter's syndrome. The direct proportionality between bradykinin stimulated PGE2 production and potassium concentrations in control fibroblasts is, despite the apparent contradiction, in accordance with findings in the literature. The lack of a comparable proportionality in fibroblasts from patients with Bartter's syndrome is interpreted to correspond to an insensitivity to changes of potassium concentrations and thus to an insensitivity to one of the modulators of AA metabolism.

Comparison of prostaglandin production of skin fibroblasts grown from patients with Bartter's syndrome and from age and sex matched controls

Basal and bradykinin stimulated release of prostaglandins (6-oxo-PGF1 alpha, PGF2 alpha, PGE2) and of arachidonic acid (C20:4) from skin fibroblast cultures of two patients with Bartter's Syndrome were compared with age and sex matched controls. PG-formation from 14C-C20:4 was studied, and for PGE2 a radioimmunoassay was also employed. The data show that in basal release, Bartter's Syndrome fibroblasts produce significantly less PGE2 than controls. Stimulated release of 6-oxo-PGF1 alpha was higher, that of PGE2 lower and that of C2O:4 higher in Bartter's Syndrome than in controls, all differences being significant. Despite equal culturing conditions the estimated intracellular potassium was higher in the patients fibroblasts than in controls. In skin fibroblasts from patients with Bartter's Syndrome stimulated prostaglandin production from C2O:4 is mostly depressed, with the exeption of prostacyclin which is enhanced. The permeability of cell membranes for potassium might play a pathogenetic role.