Central hypertensive effect of ouabain in rats

: Ouabain was infused into the third cerebral ventricle of fully conscious, pentobarbital-anaesthetized or urethane-anaesthetized rats. Convulsive seizures occurred in the freely moving rats. The blood pressure of the pentobarbital-anaesthetized rats rose inconsistently. However, in those animals, anaesthetized with urethane, a consistent cardiovascular response was observed with an initial bradycardia, followed by a progressive increase in both the blood pressure and the heart rate. The hypertension was associated with a rise in the CSF potassium level. Tachyphylaxis to these responses was observed.