In Vivo Time-Course Changes in Ethanol Levels Sampled With Subcutaneous Microdialysis
Alcoholism: Clinical and Experimental Research (OnlineEarly Articles) 22 Jan 2008

The objective of this study was to determine time-course changes in in vivo ethanol (EtOH) concentrations using a novel subcutaneous (s.c.) microdialysis sampling technique. The hypothesis to be tested was that EtOH concentrations in the s.c. fluid would reflect blood EtOH concentrations. If this is the case, then s.c. microdialysis could allow a more detailed analysis of changes in in vivo levels of EtOH under different drinking paradigms.

In vivo probe recovery (extraction fraction) obtained using the alcohol clamp method was 69 ± 3%, and was comparable to the in vitro recovery of 73 ± 2%. For the EtOH dose–response experiment, rats injected i.p. with 0.5, 1.0, or 2.0 g/kg EtOH showed a clear dose–response effect in the s.c. dialysate samples. Peak concentrations (70, 123, and 203 mg%, respectively) were reached by 15 minutes after injection. In an experiment comparing levels of EtOH in s.c. dialysis and arterial blood samples in rats administered 1.0 g/kg EtOH, similar time-course changes in in vivo EtOH concentrations were observed with both i.g. and i.p. EtOH administration. In P rats drinking 15% EtOH during a 1-hour scheduled access period, EtOH levels in s.c. microdialysates rose rapidly over the session and peaked at approximately 50 mg% at 60 to 80 minutes.

Overall, these experiments indicate that s.c. EtOH and blood EtOH concentrations follow a similar time course. Moreover, s.c. microdialysis can be useful as an experimental approach for determining detailed time-course changes in in vivo EtOH concentrations associated with alcohol drinking episodes.

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