Bradykinin-induced changes in myo-inositol 1,2-(cyclic)phosphate in rabbit papillary collecting tubule cells

Rabbit renal pipillary collecting tubule cells were harvested and grown in primary cultures. When labeled with myo-[2-³H]inositol and extracted under neutral conditions, a metabolite undetected under acidic extraction was observed on resolution by anion-exchange chromatography and which eluted under similar conditions with authentic dl-myo-inositol 1,2-(cyclic)phosphate; the mass spectrum of its pentakis(trimethylsilyl) derivative contains an identical ratio of selected ion fragments to the authentic standard. Bradykinin, demonstrated previously to increase labeling of free inositol polyphosphates, increases labeling of inositol 1,2 cyclic phosphate but over a time course subsequent to the formation of inositol trisphosphate. These observations are consistent with the model that bradykinin induces hydrolysis of phosphatidylinositol 4,5-bisphosphate which precedes hydrolysis of phosphatidylinositol in renal papillary collecting tubule cells.