1. The involvement of protein kinase C in the regulation of choline cotransport in Limulus.
- Author
-
Ford BD, Ivy MT, Mtshali CP, and Townsel JG
- Subjects
- Animals, Arachidonic Acids pharmacology, Biological Transport drug effects, Biological Transport physiology, Brain enzymology, Carcinogens pharmacology, Carrier Proteins metabolism, Cholinergic Agents pharmacokinetics, Enzyme Inhibitors pharmacology, Hemicholinium 3 pharmacokinetics, Nervous System enzymology, Organ Culture Techniques, Phorbol 12,13-Dibutyrate pharmacology, Phospholipases A metabolism, Phospholipases A2, Potassium Chloride pharmacology, Quinacrine pharmacology, Staurosporine pharmacology, Tetradecanoylphorbol Acetate pharmacology, Tritium, Choline pharmacokinetics, Horseshoe Crabs enzymology, Protein Kinase C metabolism
- Abstract
The involvement of protein kinase C (PKC) in the regulation of [3H]choline cotransport was studied in Limulus brain hemi-slice preparations. The PKC activators, phorbol 12-myristate 13-acetate (PMA) or phorbol 12,13-dibutyrate (PDBu), significantly decreased [3H]choline cotransport. Conversely, the PKC inhibitors, staurosporine (STAURO) and polymyxin B (PMB), each increased [3H]choline cotransport. These PKC inhibitors prevented the phorbol ester-induced reduction of transport. Both the PMA induced decrease and the STAURO induced increase in [3H]choline cotransport were paralleled by respective and comparable changes in [3H]hemicholinium-3 (HC-3) specific binding. Pre-exposure of brain hemi-slices to elevated potassium chloride (120 mM KCl) resulted in a doubling of [3H]choline cotransport and [3H]HC-3 binding. The enhancement of [3H]choline cotransport by STAURO and antecedent 120 mM KCl treatment were additive. PMA did not significantly alter elevated potassium stimulated transport. Moreover, arachidonyltrifluoromethyl ketone (AACOCF3) and quinacrine (QUIN), both phospholipase A2 (PLA2) inhibitors, markedly decreased enhanced [3H]choline transport and [3H]HC-3 binding induced by antecedent exposure to depolarizing concentrations of potassium. These results suggest that PKC and PLA2 are involved in the regulation of [3H]choline cotransport but at different regulatory sites.
- Published
- 1999
- Full Text
- View/download PDF