Figure 4. Temporal effects of CGS-21680 in a carotid body sham control animal 24 hours after C2 hemisection are shown. (A) The total absence of respiratory-related activity in the LPN is indicative of a functionally complete hemisection, whereas activity in the RPN is evident. (B) Ten minutes after administration of CGS-21680, there is no induced activity in the LPN; there is, however, mild onset of tonic activity that increases progressively, and by 30 minutes after administration (C), is rather obvious. Administration of the peripherally specific adenosine antagonist 8-(p-sulphophenyl)theophylline (10 mg/kg; based on previous studies) obviated the CGS-21680–induced tonicity approximately 15 minutes after administration (D), indicating that the enhanced tonic effect after CGS-21680 is mediated by A2 receptors located in the periphery.
