Oxotremorine-induced hypertension in the anaesthetized rat

1. Oxotremorine exerts an action on peripheral cholinoceptors in the anaesthetized rat. After the blockade of peripheral cholinoceptors with the quaternary atropine derivative, atropine methylbromide, oxotremorine produced a rise in arterial blood pressure and tachycardia.2. The rise in arterial pressure and tachycardia was absent in rats that had been pithed or had undergone high spinal cord transection.3. A non-quaternary atropine derivative antagonized these cardiovascular effects.4. Drugs which inhibit activity of the sympathetic nervous system antagonized the oxotremorine-induced hypertension and tachycardia.5. It is concluded that the rise in arterial pressure and tachycardia seen in the anaesthetized rat treated with a quaternary derivative of atropine is due to an action of oxotremorine on the central nervous system at a supraspinal level, resulting in an increase in activity of the efferent sympathetic nervous system.