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Mechanisms involved in the relaxing effect of midazolam on coronary arteries

Published online by Cambridge University Press:  13 April 2005

A. P. Klockgether-Radke ,
P. Pawlowski ,
P. Neumann  and
G. Hellige
A. P. Klockgether-Radke
Affiliation:
Georg-August University of Göttingen, Centre of Anaesthesiology, Emergency and Intensive Care Medicine, Department of Anaesthesiological Research, Göttingen, Germany
P. Pawlowski
Affiliation:
Georg-August University of Göttingen, Centre of Anaesthesiology, Emergency and Intensive Care Medicine, Department of Anaesthesiological Research, Göttingen, Germany
P. Neumann
Affiliation:
Georg-August University of Göttingen, Centre of Anaesthesiology, Emergency and Intensive Care Medicine, Department of Anaesthesiological Research, Göttingen, Germany
G. Hellige
Affiliation:
Georg-August University of Göttingen, Centre of Anaesthesiology, Emergency and Intensive Care Medicine, Department of Anaesthesiological Research, Göttingen, Germany
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Abstract

Summary

Background and objective: Hypotension, especially in elderly and hypovolaemic patients, is frequently associated with intravenous midazolam administration. The mechanisms are not completely understood. This study was designed to investigate the mechanisms involved in the relaxing effect of midazolam on coronary arteries.

Methods: The substance was studied in isolated porcine coronary artery rings precontracted by either potassium chloride or prostaglandin F2α.

Results: Midazolam caused vasodilatation in a concentration-dependent manner. Relaxation was more pronounced in prostaglandin F2α precontracted segments than in those treated with potassium chloride (P < 0.001). Vasodilatation was unaffected by Nω-nitro-l-arginine, indomethacin and glibenclamide. Tetraethylammonium chloride, an inhibitor of the BKCa K+ channel (a high conductance Ca2+-sensitive K+ channel), dose dependently attenuated the vasodilating effect of midazolam (P < 0.01).

Conclusions: Hyperpolarization of the smooth muscle cell in the vessel wall, elicited by the activation the BKCa K+ channel, may contribute to the vasorelaxing effect of midazolam.

Keywords

ANAESTHETICS, INTRAVENOUS, midazolamARTERIES, coronary vesselsK+ CHANNELS, BKCa channel
Type
Original Article
Information
European Journal of Anaesthesiology , Volume 22 , Issue 2 , February 2005 , pp. 135 - 139
Copyright
2005 European Society of Anaesthesiology

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