Magnesium sulfate and diphenylhydantoin relax canine middle cerebral artery contracted with the thromboxane-a2 analogue u46619 by different mechanisms: Implications for the management of eclampsia

Michael A. Belfort; George R. Saade; Kenneth J. Moise; Brian Kirshon; Paul M. Vanhoutte

doi:10.3109/10641959409084171

Magnesium sulfate and diphenylhydantoin relax canine middle cerebral artery contracted with the thromboxane-a₂ analogue u46619 by different mechanisms: Implications for the management of eclampsia

Michael A. Belfort, George R. Saade, Kenneth J. Moise, Brian Kirshon, Paul M. Vanhoutte

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

Objectives: To investigate the relaxant effect of MgSO₄ and diphenylhydantoin on isolated canine middle cerebral artery (MCA) rings contracted with the thromboxane-A₂ analogue U46619. Methods: Canine MCA rings, with and without endothelium, were suspended in organ chambers for isometric tension recording. They were contracted with U46619 in the presence of indomethacin, with and without nitro-l-arginine (NLA). Cumulative dose-response curves were performed using MgSQ₄ (10^-8 M to 10^-2 M) and diphenylhydantoin (10^-9 M to 10^-3 M). Main Outcome Measures: Tension at each concentration of the study drug expressed as a percentage of the maximum tension developed with U46619; area under the concentration response curve. Results: Both MgSO₄ and diphenylhydantoin relaxed the MCA rings irrespective of the presence of endothelium. Diphenylhydantoin caused an endothelium-dependent relaxation at concentrations above 3 10^-5 M, unaffected by NLA. Conclusions: MgSO₄ relaxes canine MCA by a direct smooth muscle effect independent of the endothelium. Diphenylhydantoin causes an endothelium-dependent relaxation of canine MCA at concentrations above 3 10^-5 M, unrelated to nitric oxide. MgSO₄ and diphenylhydantoin may both help to prevent seizures in patients with eclampsia by reducing me potential for cerebral vasospasm.

Original language	English (US)
Pages (from-to)	51-60
Number of pages	10
Journal	Hypertension in Pregnancy
Volume	13
Issue number	1
DOIs	https://doi.org/10.3109/10641959409084171
State	Published - 1994
Externally published	Yes

Keywords

Cerebral vasospasm
Diphenylhydantoin
Magnesium sulfate

ASJC Scopus subject areas

Internal Medicine
Obstetrics and Gynecology

Access to Document

10.3109/10641959409084171

Cite this

Magnesium sulfate and diphenylhydantoin relax canine middle cerebral artery contracted with the thromboxane-a₂ analogue u46619 by different mechanisms: Implications for the management of eclampsia. / Belfort, Michael A.; Saade, George R.; Moise, Kenneth J. et al.
In: Hypertension in Pregnancy, Vol. 13, No. 1, 1994, p. 51-60.

Research output: Contribution to journal › Article › peer-review

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title = "Magnesium sulfate and diphenylhydantoin relax canine middle cerebral artery contracted with the thromboxane-a2 analogue u46619 by different mechanisms: Implications for the management of eclampsia",

abstract = "Objectives: To investigate the relaxant effect of MgSO4 and diphenylhydantoin on isolated canine middle cerebral artery (MCA) rings contracted with the thromboxane-A2 analogue U46619. Methods: Canine MCA rings, with and without endothelium, were suspended in organ chambers for isometric tension recording. They were contracted with U46619 in the presence of indomethacin, with and without nitro-l-arginine (NLA). Cumulative dose-response curves were performed using MgSQ4 (10-8 M to 10-2 M) and diphenylhydantoin (10-9 M to 10-3 M). Main Outcome Measures: Tension at each concentration of the study drug expressed as a percentage of the maximum tension developed with U46619; area under the concentration response curve. Results: Both MgSO4 and diphenylhydantoin relaxed the MCA rings irrespective of the presence of endothelium. Diphenylhydantoin caused an endothelium-dependent relaxation at concentrations above 3 10-5 M, unaffected by NLA. Conclusions: MgSO4 relaxes canine MCA by a direct smooth muscle effect independent of the endothelium. Diphenylhydantoin causes an endothelium-dependent relaxation of canine MCA at concentrations above 3 10-5 M, unrelated to nitric oxide. MgSO4 and diphenylhydantoin may both help to prevent seizures in patients with eclampsia by reducing me potential for cerebral vasospasm.",

keywords = "Cerebral vasospasm, Diphenylhydantoin, Magnesium sulfate",

author = "Belfort, {Michael A.} and Saade, {George R.} and Moise, {Kenneth J.} and Brian Kirshon and Vanhoutte, {Paul M.}",

note = "Funding Information: This study was supported in part by a grant from the Women's Fund of Texas. Address correspondence and reprint requests to: Dr. Michael A. Belfort, Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX 77030. Fax: (713) 7900108. Funding Information: The authors would like to acknowledge the Women{\textquoteright}s Fund of Texas for the financial support that made this study possible. Copyright: Copyright 2014 Elsevier B.V., All rights reserved.",

year = "1994",

doi = "10.3109/10641959409084171",

language = "English (US)",

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T1 - Magnesium sulfate and diphenylhydantoin relax canine middle cerebral artery contracted with the thromboxane-a2 analogue u46619 by different mechanisms

T2 - Implications for the management of eclampsia

AU - Belfort, Michael A.

AU - Saade, George R.

AU - Moise, Kenneth J.

AU - Kirshon, Brian

AU - Vanhoutte, Paul M.

N1 - Funding Information: This study was supported in part by a grant from the Women's Fund of Texas. Address correspondence and reprint requests to: Dr. Michael A. Belfort, Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, TX 77030. Fax: (713) 7900108. Funding Information: The authors would like to acknowledge the Women’s Fund of Texas for the financial support that made this study possible. Copyright: Copyright 2014 Elsevier B.V., All rights reserved.

PY - 1994

Y1 - 1994

N2 - Objectives: To investigate the relaxant effect of MgSO4 and diphenylhydantoin on isolated canine middle cerebral artery (MCA) rings contracted with the thromboxane-A2 analogue U46619. Methods: Canine MCA rings, with and without endothelium, were suspended in organ chambers for isometric tension recording. They were contracted with U46619 in the presence of indomethacin, with and without nitro-l-arginine (NLA). Cumulative dose-response curves were performed using MgSQ4 (10-8 M to 10-2 M) and diphenylhydantoin (10-9 M to 10-3 M). Main Outcome Measures: Tension at each concentration of the study drug expressed as a percentage of the maximum tension developed with U46619; area under the concentration response curve. Results: Both MgSO4 and diphenylhydantoin relaxed the MCA rings irrespective of the presence of endothelium. Diphenylhydantoin caused an endothelium-dependent relaxation at concentrations above 3 10-5 M, unaffected by NLA. Conclusions: MgSO4 relaxes canine MCA by a direct smooth muscle effect independent of the endothelium. Diphenylhydantoin causes an endothelium-dependent relaxation of canine MCA at concentrations above 3 10-5 M, unrelated to nitric oxide. MgSO4 and diphenylhydantoin may both help to prevent seizures in patients with eclampsia by reducing me potential for cerebral vasospasm.

AB - Objectives: To investigate the relaxant effect of MgSO4 and diphenylhydantoin on isolated canine middle cerebral artery (MCA) rings contracted with the thromboxane-A2 analogue U46619. Methods: Canine MCA rings, with and without endothelium, were suspended in organ chambers for isometric tension recording. They were contracted with U46619 in the presence of indomethacin, with and without nitro-l-arginine (NLA). Cumulative dose-response curves were performed using MgSQ4 (10-8 M to 10-2 M) and diphenylhydantoin (10-9 M to 10-3 M). Main Outcome Measures: Tension at each concentration of the study drug expressed as a percentage of the maximum tension developed with U46619; area under the concentration response curve. Results: Both MgSO4 and diphenylhydantoin relaxed the MCA rings irrespective of the presence of endothelium. Diphenylhydantoin caused an endothelium-dependent relaxation at concentrations above 3 10-5 M, unaffected by NLA. Conclusions: MgSO4 relaxes canine MCA by a direct smooth muscle effect independent of the endothelium. Diphenylhydantoin causes an endothelium-dependent relaxation of canine MCA at concentrations above 3 10-5 M, unrelated to nitric oxide. MgSO4 and diphenylhydantoin may both help to prevent seizures in patients with eclampsia by reducing me potential for cerebral vasospasm.

KW - Cerebral vasospasm

KW - Diphenylhydantoin

KW - Magnesium sulfate

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