Study of the effect of central administration of prostigmine and atropine on the exercise pressor reflex in anesthetized rats

ABSTRACT

This study included 20 rats, exposed to muscular manipulation in the form of static contraction and passive stretch of triceps surae muscle. These manipulations increased e basal MAP and HR [exercise pressor reflex]. Central prostigmine injection had not any effect on the resting MAP and HR. Prostigmine inhibited the contraction evoked responses of the MAP and HR, also it blunted the MAP and HR response to passive stretch. Then the rats were divided into two groups, group I included 10 rats, in this group the rats are left 90-120 min after prostigmine injection, this is considered as a recovery period, the cardiovascular responses to muscular manipulation are returned to normal responses after this recovery period, the muscular manipulation caused a significant increase of both MAP and HR. Group II of ten rats exposed to central administration of atropine [muscurinic antagonist] and one hour later prostigmine was injected centraly, atropine blocked the prostigmine inhibitory effect on the MAP and HR in response to muscular manipulation. Muscular contraction and passive stretch in this group caused a significant increase of MAP and HR. These results suggest that central cholinergic system stimulation could inhibit the exercise pressor reflex in the anesthetized rats