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Stereoselectivity of extraneuronal uptake of catecholamines in guinea‐pig trachealis smooth muscle cells
Author(s) -
Bryan Lesley J.,
O'Donnell Stella R.
Publication year - 1984
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.1476-5381.1984.tb10815.x
Subject(s) - isoprenaline , trachealis muscle , chemistry , guinea pig , medicine , endocrinology , epinephrine , norepinephrine , catecholamine , stereoselectivity , biology , stimulation , biochemistry , smooth muscle , dopamine , charybdotoxin , catalysis
1 The extraneuronal uptake of the (‐)‐ and (+)‐isomers of three catecholamines, isoprenaline, adrenaline and noradrenaline, were compared in guinea‐pig trachealis smooth muscle cells, by a fluorescence microphotometric method. 2 Preliminary experiments showed that the initial rates of uptake of the (‐)‐isomers were greater than those of the (+)‐isomers in tissues incubated in 25 μ m adrenaline or noradrenaline or 50 μ m isoprenaline. 3 More detailed experiments showed that the K m values of the (+)‐isomers of the amines for extraneuronal uptake were not significantly different from each other, but the K m value of (‐)‐isoprenaline < (‐)‐adrenaline < (‐)‐noradrenaline. Thus, the order of the ratios of the K m values for the (+):(‐)‐isomers was isoprenaline > adrenaline > noradrenaline. 4 The results showed that there is stereoselectivity of the extraneuronal uptake of catecholamines, but it is greatest for isoprenaline (4.9 fold), less for adrenaline (2.5 fold) and almost negligible (1·6 fold) for noradrenaline.