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Effects of almitrine on the release of catecholamines from the rabbit carotid body in vitro
Author(s) -
Almaraz L.,
Rigual R.,
Obeso A.,
Evrard Y.,
Gonzalez C.
Publication year - 1992
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1992.tb14397.x
Subject(s) - chemoreceptor , carotid body , endocrinology , dopamine , medicine , mechanism of action , chemistry , veratridine , in vitro , biology , pharmacology , biochemistry , stimulation , sodium , receptor , organic chemistry , sodium channel
1 . Almitrine increases ventilation by stimulating the carotid body (CB) arterial chemoreceptors but neither its intraglomic target nor its mechanism of action have been elucidated. 2 . We have tested the hypothesis that chemoreceptor cells are targets for almitrine by studying its effects on the release of 3 H‐catecholamines in an in vitro rabbit CB preparation. 3 . It was found that almitrine (0.3 and 1.5 × 10 −6 m ; i.e. 0.2 and 1 mg l −1 ) increases the resting release of 3 H‐catecholamines from CBs (previously loaded with [ 3 H]‐tyrosine) incubated in a balanced 95% O 2 /5% CO 2 ‐equilibrated solution. 4 . Almitrine at a concentration of 3×10 −6 m (2mg l −1 ) also augmented the release of 3 H‐catecholamines elicited by incubating the CBs in a hypoxic solution (equilibrated with 7% O 2 /5% CO 2 in N 2 ), by high external K + (35 m m ) and by veratridine (2 × 10 −5 m ), but did not modify release induced by dinitrophenol (7.5 × 10 −5 m ). 5 . At the same concentration (3 × 10 −6 m ), almitrine increased the rate of dopamine synthesis and was ineffective in modifying the cyclic AMP levels in either normoxic or hypoxic CBs. 6 . It is concluded that chemoreceptor cells are the intraglomic targets for almitrine. The mechanisms of action of almitrine on chemoreceptor cells are discussed.