In vivo release of non-neuronal acetylcholine from the human skin as measured by dermal microdialysis: effect of botulinum toxin.
1.--Acetylcholine is synthesized in the majority of non-neuronal cells, for example in human skin. In the present experiments, the in vivo release of acetylcholine was measured by dermal microdialysis. 2.--Two microdialysis membranes were inserted intradermally at the medial shank of volunteers. Physiological saline containing 1 muM neostigmine was perfused at a constant rate of 4 microl min(-1) and the effluent was collected in six subsequent 20 min periods. Acetylcholine was measured by high-pressure liquid chromatography (HPLC) combined with bioreactors and electrochemical detection. 3.--Analysis of the effluent by HPLC showed an acetylcholine peak that disappeared, when the analytical column was packed with acetylcholine-specific esterase, confirming the presence of acetylcholine. 4.--In the absence of neostigmine, 71+/-51 pmol acetylcholine (n=4) was found during a 120 min period. The amount increased to 183+/-43 pmol (n=34), when the perfusion medium contained 1 microM neostigmine. 5.--Injection of 100 MU botulinum toxin subcutaneously blocked sweating completely, but the release of acetylcholine was not affected (botulinum toxin treated skin: 116+/-70 pmol acetylcholine/120 min; untreated skin: 50+/-20 pmol; n=4). 6.--Quinine (1 mM), inhibitor of organic cation transporters, and carnitine (0.1 mM), substrate of the Na(+)-dependent carnitine transporter OCTN2, tended to reduce acetylcholine release (by 40%, not significant). 7.--Our experiments demonstrate, for the first time, the in vivo release of non-neuronal acetylcholine in human skin. Organic cation transporters are not predominantly involved in the release of non-neuronal acetylcholine from the human skin.
Schlereth
Tanja
T
Department of Neurology, Johannes-Gutenberg-University Mainz, Reisinger Weg, Langenbeckstrasse 1, D-55101 Mainz, Germany. schleret@uni-mainz.de
Birklein
Frank
F
an Haack
Katrin
K
Schiffmann
Susanne
S
Kilbinger
Heinz
H
Kirkpatrick
Charles James
CJ
Wessler
Ignaz
I
D000109:Acetylcholine / Q000378:metabolism*; D000328:Adult; D001905:Botulinum Toxins / Q000008:administration & dosage / Q000494:pharmacology*; D002331:Carnitine / Q000494:pharmacology; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D017551:Microdialysis; D027701:Organic Cation Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D011803:Quinine / Q000494:pharmacology; D012867:Skin / Q000187:drug effects* / Q000378:metabolism; D000074058:Solute Carrier Family 22 Member 5; D013545:Sweat Glands / Q000187:drug effects / Q000378:metabolism
D027701:Organic Cation Transport Proteins; C492020:SLC22A5 protein, human; D000074058:Solute Carrier Family 22 Member 5; D011803:Quinine; D001905:Botulinum Toxins; D000109:Acetylcholine; D002331:Carnitine