CHARACTERISTICS OF INOSITOL POLYPHOSPHATE METABOLISM IN CULTURED ADRENAL CHROMAFFIN CELLS

1. Nicotine, high K+ and maitotoxin caused the inositol polyphosphate accumulation concomitant with Ca-45(2+) uptake. 2. Angiotensin II (Ang II) and ATP induced the inositol polyphosphate accumulation without C a-45(2+) uptake. 3. Nifedipine-treatment and Ca2+-deprivation inhibite d the high K+-induced inositol polyphosphate accumulation but failed t o inhibit the Ang II-induced inositol polyphosphate accumulation. 4. 1 2-O-tetradecanoylphorbol-13-acetate inhibited the Ang II-induced inosi tol polyphosphate accumulation but failed to inhibit the high K+-induc ed one 5. These results suggest that the formation of inositol polypho sphates may be regulated by two mechanisms, i.e. Ca2+ uptake-dependent mechanisms represented by high K+, and Ca2+ uptake-independent mechan isms represented by Ang II.