Effect of calcium on dopamine uptake in rat striatal synaptosome

• Published in: Japanese Journal of Pharmacology 1994, Vol.64 (suppl.1), p.122-122
• Main Authors: Uchikawa, Tomovoshi, Kiuchi, Yuji, Nakachi, Noriyuki, Yamazaki, Yukako, Yokomizo, Chie, Oguchi, Katsuji
• Format: Article
• Language: eng ; jpn
• ISSN: 0021-5198
• DOI: 10.1016/S0021-5198(19)50132-9

Dopamine (DA) uptake to neuronal terminals is known to be affected by extracelluler calcium concentration. In this study, we attempted to clarify underlying mechanisms in this phenomenon.The uptake experiment was performed on a crude synaptosomal fraction prepared from reserpine-pretreated male Sprague-Dawley rats (7 weeks old). The synaptosome was preincubated for 0-30 min at 37℃ in a modified Krebs-Ringer medium (KR) containing 0-10 mM CaCl_2 . The incubation was routinely continued in the presence of 50 nM 「^^3 H」DA for 3 min. Preincubation increased 「^^3 H」DA uptake with time up to 10 min. After 10 min preincubation, the uptake in KR with 0, 0.5, 1, 5 and 10 mM CaCl_2 increased 1.2, 1.9, 2.4, 2.1 and 1.3 times, respectively, compared to those without preincubation. This increase was mainly attributed to that of Vmax in a DA uptake process. On the other hand, ionomycin immediately inhibited the uptake intensely. Calcium and preincubation time-dependent increase in the uptake was reversed by H-7, an antagonist of protein kinase. These results indicate that calcium may regulate DA uptake in the striatal synaptosome through a protein kinase-dependent mechanism.