Regulation of Anterior Pituitary D2 Dopamine Receptors by Magnesium and Sodium Ions |
| |
Authors: | Masayuki Watanabe Susan R George† Philip Seeman |
| |
Institution: | Department of Pharmacology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada;Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada |
| |
Abstract: | At D2 3,4-dihydroxyphenylethylamine (dopamine) receptors in anterior pituitary tissue, magnesium ions shifted receptors to agonist high-affinity states, but decreased the affinity of the antagonist 3H]spiperone. Conversely, sodium ions shifted the receptors to agonist low-affinity states, but increased the affinity of 3H]spiperone. Magnesium is proposed to stabilize the hormone-receptor-guanine nucleotide regulatory protein complex, whereas sodium appears to destabilize this ternary complex. Thus, magnesium and sodium appear to mediate their regulatory effects via a common component at the D2 dopamine-receptor ternary complex. |
| |
Keywords: | D2 dopamine-receptors-Anterior pituitary Ternary complex Magnesium ions Sodium ions |
|
|