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.