Figure 1. Examples of the short-latency monosynaptic reflex (MSR) and the long-lasting slow ventral root potential (VRP). (A) The dose-dependent inhibition of the MSR produced by N6-(R)-phenylisopropyladenosine (R-PIA). (B) The dose-dependent inhibition of the slow VRP produced by 5'-N-ethylcarbox-amidoadenosine (NECA). The effects of cumulative doses on both responses are reversed to the control levels by theophylline (25 micro Meter) application.