In the landmark paper discussed in this chapter, published in 1982, LaMotte et al. investigated the contribution of different cutaneous nerve fibres to heat pain and heat hyperalgesia in both psychophysical (humans) and electrophysiological studies (human and primates), using identical thermal test and conditioning stimuli; the findings from the two sets of experiments were then correlated. In non-human primates, neuronal activity was recorded from mechanoheat-sensitive A- and C-fibres (AMHs and CMHs, respectively) and warm and cold fibres, whereas, in conscious human volunteers, activity from CMHs was recorded. The authors found that pain is mediated by activity in CMHs and that sensitization of CMHs after a mild burn injury accounts for the increased heat pain after such injury. The combination of psychophysical experiments in human and correlative electrophysiological studies in non-human primates provides an important experimental approach for unravelling the contribution of different classes of afferents to pain.
Assessment of Drug Delivery Kinetics to Epidermal Targets In Vivo
