Facilitation of the flexor reflex in the cat by intrathecal injection of catecholamines

1. Effects of some alpha- and beta-adrenoceptor stimulants and antagonists were investigated on flexor reflex (FR) in chloralosed cats.2. Noradrenaline (NA) produced facilitation of FR which was dose-dependent and reproducible and was blocked by alpha-adrenoceptor blocking agents.3. Strychnine also produced facilitation of FR but the response was unaffected by alpha-adrenoceptor blocking agents.4. Metaraminol and alpha-methyl-noradrenaline had little effect on FR but blocked the NA response.5. beta-adrenoceptor stimulants and antagonists had neither any effect on FR nor modified the NA response.6. Vasopressin and histamine also failed to modify FR.7. Possibility of alpha-adrenoceptors in the neurones integrating FR is suggested.