TY - JOUR T1 - Insoluble Solid Complexes of Norepinephrine and Adenosine Triphosphate JF - Molecular Pharmacology JO - Mol Pharmacol SP - 88 LP - 94 VL - 8 IS - 1 AU - E. W. MAYNERT AU - B. H. MOON AU - V. S. PAI Y1 - 1972/01/01 UR - http://molpharm.aspetjournals.org/content/8/1/88.abstract N2 - Dilution with H2O of aqueous solutioins 0.5 M in norepinephrine HCl and 0.125 M in ATP (pH range, 3-7) yielded precipitates in 5-10% yield. In contrast, the products obtained by lyophilization of either the concentrated solutions or the filtrates from the precipitates readily dissolved in the original volume of H2O. The insoluble solid obtained at pH 7 had the proper elementary composition and infrared and 1H nuclear magnetic resonance spectra for a 4:1 norepinephrine·ATP complex. The precipitate produced at pH 3 was composed mostly of the 3:1 complex but appeared to contain a small amount of the 4:1 complex. In the preparation of these solids, ATP could be used as the 2Na+, Mg++, or 2(CH3)4N+ salt, but no precipitates were observed when norepinephrine bitartrate or the hydrochlorides of epinephrine or a variety of other phenethylamines were substituted for norepinephrine HCl. The maximum solubility of the complexes in H2O was estimated at 0.2 mM. This value was approximately doubled in 1.5% NaCl or KCl, and increased about 50 times in MgCl2 or CaCl2 of the same concentration. Dilution of aqueous solutions containing norepinephrine and ADP precipitated a 3:1 complex at pH 7, and a 2:1 complex at pH 3. AMP also formed an insoluble complex. The 4:1 norepinephrine·ATP complex was recovered unchanged upon neutralization of a solution in 0.1 N HCl. However, longer exposure to acidic conditions yielded the 3:1 norepinephrine·ADP complex. The 4:1 norepinephrine·ATP complex was more resistant to hydrolysis in 0.1 N HC1 than was ATP or a mixture of norepinephrine and ATP. Insoluble complexes of catecholamines and ATP could account for the calculated hypertonicity and the nondiffusibility of the amines in adrenal medullary granules. ER -