Effects of calcium and phosphate on catecholamines, ATP and dopamine beta-hydroxylase of chromaffin medullary granules.
Isolated bovine chromaffin granules lost their catecholamines to a significantly higher degree when incubated in isotonic sucrose-buffer of pH 7.4 containing 10 and 25 mM sodium phosphate, respectively, than during incubatation in sucrose with 4 mM sodium phosphate. 2. In 4mM sodium phosphate-sucrose, CaCl(2) in  a final concentration of 1 and 2 mM, respectively, produced only traces of an amorphous precipitate of calcium phosphate which increased the efflux of catecholamines only to a small degree. The same concentrations of CaCl(2) in 10 and 25 mM sodium phosphate containing sucrose solutions caused larger amounts of calcium phosphate precipitate and simultaneously a very high efflux of catecholamines. Small amounts of exogenous ATP (1 mM) and MgCl(2) (0.3 mM) effectively antagonized the efflux of catecholamines from the granules evolked by calcium phosphate...
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000313:Adrenal Medulla / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology*; D002122:Calcium Chloride / Q000494:pharmacology; D002130:Calcium Phosphates / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D011232:Chemical Precipitation; D003594:Cytoplasmic Granules / Q000378:metabolism*; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D010710:Phosphates / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism
D002130:Calcium Phosphates; D002395:Catecholamines; D010710:Phosphates; D011506:Proteins; D000255:Adenosine Triphosphate; D004299:Dopamine beta-Hydroxylase; D008274:Magnesium; D002122:Calcium Chloride; D002118:Calcium