Abstract | OBJECTIVE:
Magnesium sulfate (MgSO4) is widely used for the treatment of eclampsia. However, effects of Mg2+ in central cardiovascular regulation remain unclear. In the present study, the role of Mg2+ on cardiovascular regulation in the rostral ventrolateral medulla (RVLM) of rats was examined. METHODS: Adult male Wistar rats were anesthetized with urethane, and artificially ventilated. The ventral surface of the medulla was exposed, and the RVLM was identified by microinjection (50 nl) of l-glutamate (l-Glu; 2 nmol). Then, MgSO4 (1, 3, 10 nmol, n = 7 for each dose) and magnesium chloride (MgCl2; 10 nmol, n = 7) were microinjected into the RVLM. l-Glu (2 nmol), N-methyl-D-aspartate ( NMDA; 20 pmol), alpha-amino-3-hydroxy-5-methyl isoxazole-4-propionic acid ( AMPA; 5 pmol) and (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid [(1S,3R)-ACPD, metabotropic glutamate receptor agonist; 1 nmol] were also microinjected with or without pretreatment of MgSO4 (10 nmol; n = 7 for each drug). RESULTS: MgSO4 dose-dependently decreased mean arterial pressure (MAP) and heart rate (HR). The high dose of MgSO4 (10 nmol) significantly decreased MAP and HR (-25 +/- 4 mmHg and -43 +/- 6 bpm). Similarly, MgCl2 decreased MAP and HR (-27 +/- 4 mmHg and -30 +/- 6 bpm). The pressor response evoked by NMDA or (1S,3R)-ACPD was significantly attenuated by the pretreatment with MgSO4. In contrast, pressor response caused by l-Glu or AMPA was not affected by pretreatment with MgSO4. CONCLUSIONS: These results suggest that Mg2+ has an inhibitory role on the RVLM neurons, and inhibits cardiovascular responses induced by NMDA and metabotropic glutamate receptor agonists.
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Authors | S Kagiyama, T Tsuchihashi, M I Phillips, I Abe, K Matsumura, M Fujishima |
Journal | Journal of hypertension
(J Hypertens)
Vol. 19
Issue 12
Pg. 2213-9
(Dec 2001)
ISSN: 0263-6352 [Print] England |
PMID | 11725166
(Publication Type: Journal Article)
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Chemical References |
- Excitatory Amino Acid Agonists
- Receptors, Metabotropic Glutamate
- Receptors, N-Methyl-D-Aspartate
- Magnesium Chloride
- Cycloleucine
- 1-amino-1,3-dicarboxycyclopentane
- Glutamic Acid
- N-Methylaspartate
- Magnesium Sulfate
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
- Magnesium
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Topics |
- Animals
- Blood Pressure
(drug effects)
- Cardiovascular Physiological Phenomena
(drug effects)
- Cycloleucine
(analogs & derivatives, pharmacology)
- Dose-Response Relationship, Drug
- Excitatory Amino Acid Agonists
(pharmacology)
- Glutamic Acid
(pharmacology)
- Heart Rate
(drug effects)
- Magnesium
(pharmacology)
- Magnesium Chloride
(pharmacology)
- Magnesium Sulfate
(pharmacology)
- Male
- Medulla Oblongata
(drug effects, physiology)
- N-Methylaspartate
(pharmacology)
- Rats
- Rats, Wistar
- Receptors, Metabotropic Glutamate
(physiology)
- Receptors, N-Methyl-D-Aspartate
(physiology)
- alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
(pharmacology)
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