Pharmacological FMRI: measuring opioid effects upon the BOLD response to hypercapnia
Wise R, Tracey I, Mayhew S, Rogers R, Pattinson K
Oxford University, Oxford University
This study investigated the effect of a mu-opioid agonist remifentanil, upon cerebrovascular CO2 reactivity, using BOLD FMRI. We delivered hypercapnic challenges to human volunteers, while controlling potential opioid-induced respiratory depression. We compared the BOLD signal increase to elevated CO2 before and during remifentanil administration. We have determined that remifentanil does not have a generalised effect on CO2 responsiveness in the cerebral vasculature. This allows us to interpret drug induced changes in BOLD signal with more confidence and we suggest that similar methodology to assess pharmacological influences on vascular reactivity should be used when investigating new compounds with FMRI.