The effect of oxotremorine on blood pressure and plasma catecholamines in conscious and anesthetized rats

Oxotremorine causes a pressor response in conscious rats which is associated with a large increase in circulating catecholamines. This effect is reduced by urethane and abolished by pentobarbital anesthesia. Atropine methyl nitrate antagonises the initial brady-cardia and hypotension induced by oxotremorine and reduces significantly the rise in plasma norepinephrine but not that of epinephrine. Oxotremorine appears to activate the sympathetic nervous system by at least two mechanisms: reflexly through baroreceptors, and directly by stimulation of muscarinic receptors in the central nervous system.