Midazolam depresses carotid body chemoreceptor activity.

Abstract

BACKGROUND:

Although the contribution of the gamma-aminobutyric acid (GABA) receptor system in peripheral chemosensation is unclear, immunohistochemistry has demonstrated the presence of GABA-ergic receptors in mammalian carotid bodies. We hypothesized that an activation of the carotid body GABA receptors would counteract the depolarizing effect of hypoxia.

METHODS:

The carotid body with arterial supply and the carotid sinus nerve was removed en bloc from New Zealand White rabbits and placed in a perfusion chamber. The carotid body preparation was perfused via the cut common carotid artery with a modified Tyrode's solution at a rate of 3.5-4.5 ml/min with a constant pressure of 45 cmH2O. The carotid sinus nerve firing frequency (Hz) was recorded at two different oxygen tension levels during perfusion with midazolam of 1, 10 and 100 microg/l.

RESULTS:

The frequency was decreased by midazolam in a dose-dependent manner (n = 8). Firing frequencies (mean +/- SEM) at the low oxygen tension level decreased from 643.13 +/- 67.2 Hz in the control to 554.5 +/- 67.7 Hz (P = 0.054 vs. control), 509.01 +/- 100.5 Hz (P < 0.012 vs. control) and 422.6 +/- 77.3 Hz (P < 0.001 vs. control) during perfusion with midazolam of 1, 10 and 100 microg/l, respectively.

CONCLUSION:

Midazolam depresses carotid body chemoreceptor activity in a dose-dependent manner.

• Authors: C Kim, Y Shvarev, S Takeda, A Sakamoto, S G E Lindahl, L I Eriksson
• Journal: Acta anaesthesiologica Scandinavica (Acta Anaesthesiol Scand) Vol. 50 Issue 2 Pg. 144-9 (Feb 2006) ISSN: 0001-5172 [Print] England
• PMID: 16430533 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anesthetics, Intravenous
• Receptors, GABA
• Carbon Dioxide
• Sodium
• Midazolam
• Potassium
• Oxygen

Topics

• Action Potentials (drug effects)
• Analysis of Variance
• Anesthetics, Intravenous (pharmacology)
• Animals
• Carbon Dioxide (metabolism)
• Carotid Body (drug effects)
• Carotid Sinus (drug effects, innervation)
• Chemoreceptor Cells (drug effects)
• Hypoxia (chemically induced)
• In Vitro Techniques
• Male
• Midazolam (pharmacology)
• Oxygen (metabolism)
• Potassium (metabolism)
• Rabbits
• Receptors, GABA (drug effects)
• Sodium (metabolism)
• Time Factors