Magnesium decreases arterial pressure and inhibits cardiovascular responses induced by N-methyl-D-aspartate and metabotropic glutamate receptors stimulation in rostral ventrolateral medulla.

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.

• 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)

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

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)