| 12559396 |
Matsumoto S, Ikeda M, Nishikawa T, Yoshida S, Kadoi J, Tanimoto T, Saiki C, Takeda M: Effects of acetazolamide and 4-aminoprydine on the responses of deflationary slowly adapting pulmonary stretch receptors to CO2 inhalation in the rat. Life Sci. 2003 Feb 28;72(15):1757-71.
The inhibitory effect of CO (2) on deflationary slowly adapting pulmonary stretch receptors (deflationary SARs) was investigated before and after administration of acetazolamide, a carbonic anhydrase (CA) inhibitor, or 4-aminopyridine (4-AP), a K (+) channel blocker, in anesthetized, artificially ventilated rats after unilateral vagotomy. CO (2) inhalation (maximum tracheal CO (2) concentration ranging from 9 to 12%) for approximately 60 s decreased the impulse activity of deflationary SARs but had no significant effect on tracheal pressure (P (T)) as an index of bronchomotor tone. Acetazolamide treatment (20 mg/kg) diminished the inhibitory response of deflationary SARs to CO (2) inhalation. 4-AP (0.7 and 2.0 mg/kg) dose-dependently attenuated the decrease in deflationary SAR activity induced by CO (2) inhalation. When comparing the maximum attenuation due to 4-AP (2.0 mg/kg) and acetazolamide (20 mg/kg) in CO (2)-induced deflationary SAR inhibition, blockade of K (+) channels had a more pronounced effect. These results suggest that inhibition of deflationary SARs by CO (2) inhalation may be largely mediated by the stimulating action of 4-AP-sensitive K (+) currents in the nerve terminals of the receptors. |
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