Rapid adenosine release in the nucleus tractus solitarii during defence response in rats: real-time measurement in vivo

Research output: Contribution to journalArticle

Authors

  • N Dale
  • AV Gourine
  • E Llaudet
  • D Bulmer
  • KM Spyer

Colleges, School and Institutes

Abstract

We have measured the release of adenosine and inosine from the dorsal surface of the brainstem and from within the nucleus tractus solitarii (NTS) during the defence response evoked by hypothalamic stimulation in the anaesthetised rat. At the surface of the brainstem, only release of inosine was detected on hypothalamic defence area stimulation. This inosine signal was greatly reduced by addition of the ecto-5'-nucleotidase inhibitor alpha,beta-methylene ADP (200 muM), suggesting that the inosine arose from adenosine that was produced in the extracellular space by the prior release of ATP. By placing a microelectrode biosensor into the NTS under stereotaxic control we have recorded release of adenosine within this nucleus. By contrast to the brainstem surface, a fast increase in adenosine, accompanied only by a much smaller change in inosine levels, was seen following stimulation of the hypothalamic defence area. The release of adenosine following hypothalamic stimulation was mainly confined to a narrow region of the NTS some 500 mum in length around the level of the obex. Interestingly the release of adenosine was depletable: when the defence reaction was evoked at short time intervals, much less adenosine was released on the second stimulus. Our novel techniques have given unprecedented real-time measurement and localisation of adenosine release in vivo and demonstrate that adenosine is released at the right time and in sufficient quantities to contribute to the cardiovascular components of the defence reaction.

Details

Original languageEnglish
Pages (from-to)149-160
Number of pages12
JournalThe Journal of Physiology
Volume544
Issue number1
Early online date26 Jul 2002
Publication statusPublished - 1 Oct 2002