Midazolam depresses carotid body chemoreceptor activity

• Published in: Acta anaesthesiologica Scandinavica 2006-02, Vol.50 (2), p.144-149
• Main Authors: Kim, C., Shvarev, Y., Takeda, S., Sakamoto, A., Lindahl, S. G. E., Eriksson, L. I.
• Format: Article
• Language: English
• Subjects: Action Potentials - drug effects; Analysis of Variance; Anesthetics, Intravenous - pharmacology; Animals; Carbon Dioxide - metabolism; carotid body; Carotid Body - drug effects; Carotid Sinus - drug effects; Carotid Sinus - innervation; Chemoreceptor Cells - drug effects; GABA; Hypoxia - chemically induced; In Vitro Techniques; Male; Medicin och hälsovetenskap; midazolam; Midazolam - pharmacology; nAChR; Oxygen - metabolism; oxygen tension; Potassium - metabolism; Rabbits; Receptors, GABA - drug effects; Sodium - metabolism; Time Factors
• ISSN: 0001-5172; 1399-6576
• DOI: 10.1111/j.1399-6576.2005.00896.x

Background:  Although the contribution of the γ‐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 µg/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