The stimulant cathine from Khat causes tachycardia indirectly in the rat

Leaves of the Khat plant are widely consumed in the Horn of Africa, Yemen and the Jazan region of Saudi Arabia. I have investigated the mode of cardiovascular and autonomic actions of the stimulant cathine from Khat in terms of direct or indirect adrenergic actions in anaesthetised male and female rats, and in isolated tissues. Male and female rats were anaesthetised with pentobarbitone and changes in diastolic blood pressure and cardioaccelerator responses were examined in vehicle-treated or chemically sympathectomised rats. Cathine produced marked tachycardia and smaller blood pressure responses in vehicle-treated animals, with significant rises in heart rate occurring at cathine (0.1 mg/kg). In sympathectomised rats, cardiac actions were greatly attenuated in both male and female animals, with no differences between male and female rats. Although pressor responses to cathine were relatively small, sympathectomy significantly reduced these responses in female, but not male, rats. In rat aorta and spleen, cathine produced almost no direct contractions. It is concluded that cathine acts predominantly indirectly, presumably by the release of noradrenaline, in both male and female rats to produce cardiovascular actions. This may have implications for adverse cardiovascular actions of consumption of the plant Khat, particularly with dried Khat, in which actions of cathine may predominate over those of cathinone.