Blood pressure response to Ro15-1788, a benzodiazepine antagonist

The effects of Ro15-1788, a benzodiazepine antagonist, on heart rate and blood pressure were studied in chloralose anesthetized cats. In previously untreated controls, Ro15-1788 lowered both systolic and diastolic arterial pressure about 15 mm Hg, and slightly decreased heart rate. In cats that had been given a single acute dose of diazepam or flurazepam, Ro15-1788 increased blood pressure about 40 mm Hg. A similar increase was measured in cats that were tolerant and physically dependent after 5 weeks of chronic flurazepam treatment. High spinal (C-1) section abolished all Ro15-1788 effects. It is suggested that the observed drug actions occur within the CNS rather than in the periphery, and that it might be useful to study further the cardiovascular actions of benzodiazepine agonists and antagonists.