Effects of intravenous magnesium infusion on in vivo release of acetylcholine and catecholamine in rat adrenal medulla

详细信息    查看全文

• 作者：Fumiaki Komaki ; Tsuyoshi Akiyama ; Toji Yamazaki ; Hirotoshi Kitagawa ; Syuichi Nosaka ; Mikiyasu Shirai
• 关键词：Anesthetized rats ; Microdialysis technique ; Magnesium ; Acetylcholine ; Norepinephrine ; Epinephrine
• 刊名：Autonomic Neuroscience
• 出版年：2013
• 出版时间：October, 2013
• 年：2013
• 卷：177
• 期：2
• 页码：123-128
• 全文大小：258 K

文摘

We applied microdialysis technique to the left adrenal medulla of anesthetized rats and examined the effects of intravenous Mg^2 + infusion on presynaptic acetylcholine (ACh) release and postsynaptic catecholamine release induced by electrical stimulation of splanchnic nerves. The dialysis probes were perfused with Ringer's solution containing neostigmine. Low-dose MgSO₄ (25 ¦Ìmol/kg/min for 30 min i.v.) increased mean plasma Mg^2 + concentration to 2.5 mM; the administration suppressed norepinephrine (NE) release by approximately 30 % and epinephrine (Epi) release by approximately 20 % , but did not affect ACh release. High-dose MgSO₄ (50 ¦Ìmol/kg/min for 30 min i.v.) increased mean plasma Mg^2 + concentration to 3.8 mM; the administration suppressed ACh release by approximately 25 % , NE release by approximately 60 % and Epi release by approximately 45 % . Administration of Na₂SO₄ (50 ¦Ìmol/kg/min for 30 min i.v.) did not change the release of ACh, NE or Epi. Local administration of nifedipine (200 ¦ÌM) suppressed NE release by approximately 40 % and Epi release by approximately 30 % , but did not affect ACh release. In the presence of nifedipine, low-dose MgSO₄ did not suppress the release of ACh, or further suppress NE or Epi compared to nifedipine alone, but high-dose MgSO₄ suppressed ACh release by approximately 25 % and further suppressed NE release by approximately 60 % and Epi release by approximately 50 % compared to nifedipine alone. In conclusion, intravenous administration of Mg^2 + inhibits both presynaptic ACh release and postsynaptic catecholamine release in the adrenal medulla, but L-type Ca^2 + channel-controlled catecholamine release may be more sensitive to Mg^2 + than non-L-type Ca^2 + channel-controlled ACh release.