RESUMEN
Influences of intracerebroventricular(icv) ouabain on cardiovascular system and on pressor response to raised intracranial pressure(ICP) were investigated in urethane-anesthetized rabbits. Intravenous(iv) 40 microgram/kg ouabain did not affect blood pressure of rabbit. Icv ouabain(5, 10, 20 microgram/kg) and digoxin(6.25, 12.5 microgram/kg) produced dose-dependent pressor responses and marked decrease of heart rate. After bilateral vagotomy, the bradycardiac effect of ouabain disappeared, while the pressor effect was significantly potentiated. The ouabain-induced pressor effect was not affected by iv and icy phentolamine or propranolol, and significantly inhibited by icy infusion of lidocaine(0.1 mg/kg/min) and diazepam(0.025 mg/kg/min). The pressor response to raised ICP was not affected by iv 40 microgram/kg ouabain but disappeared by icy 10 microgram/kg ouabain and 6.25 microgram/kg digoxin. These data suggests that ouabain causes pressor effect through direct interaction with a site(s) in central nervous system and bradycardiac effect by direct activation of vagal center, and ouabain blocks central sympathetic stimulation by increase of ICP in rabbits.