title: Intracellular pH and catecholamine synthesis in cultured bovine adrenal medullary cells: effect of extracellular Na+ removal.
abstract: Incubation of cultured bovine adrenal medullary cells in Na+-free sucrose medium or in Na+-free Cs+ medium enhanced the synthesis of 14C-catecholamines from [14C]tyrosine about two- to threefold or sixfold, respectively. The increment of 14C-catecholamine synthesis produced by Na+-free medium was partially dependent on the presence of Ca2+ in the medium. Dibutyryl cyclic AMP also stimulated the synthesis of 14C-catecholamines in adrenal medullary cells, and the effects of Na+ removal and dibutyryl cyclic AMP (5 mM) on the synthesis were almost additive. The intracellular pH measured by using a weak acid 5,5-dimethyloxazolidine-2,4-dione was 7.14 in control cells and when Na+ was replaced by sucrose or Cs+, it shifted down to 6.56 or 5.66, respectively. The fall in intracellular pH and the stimulation of 14C-catecholamine synthesis were similarly dependent on the concentration of Na+ in the medium. The optimal pH of soluble tyrosine hydroxylase was 5.5-6.0 both in control cells and in cells incubated in Na+-free medium. These results suggest that removal of extracellular Na+ increases the synthesis of catecholamines, at least in part, by shifting the intracellular pH toward the optimal pH of tyrosine hydroxylase.
mesh_terms: D000313:Adrenal Medulla / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002395:Catecholamines / Q000096:biosynthesis*; D002417:Cattle; D002478:Cells, Cultured; D002586:Cesium / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D003470:Culture Media; D004298:Dopamine / Q000096:biosynthesis; D004837:Epinephrine / Q000096:biosynthesis; D006863:Hydrogen-Ion Concentration; D008094:Lithium / Q000494:pharmacology; D018021:Lithium Chloride; D009638:Norepinephrine / Q000096:biosynthesis; D012964:Sodium / Q000494:pharmacology / Q000502:physiology*; D013395:Sucrose / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D002395:Catecholamines; D002712:Chlorides; D003470:Culture Media; D002586:Cesium; D014443:Tyrosine; D013395:Sucrose; D003994:Bucladesine; D002217:Carbachol; D008094:Lithium; D012964:Sodium; D014446:Tyrosine 3-Monooxygenase; D018021:Lithium Chloride; C028019:cesium chloride; D002118:Calcium; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine