Effects of verapamil and amiodarone on sympathoadrenal system and balance of excitatory and inhibitory amino acids in rat medulla oblongata.

Local injection of verapamil into ventrolateral region of the medulla oblongata triggered the release of epinephrine. Verapamil increased the total content of norepinephrine and epinephrine by 560% and decreased the content of serotonin by 46%. Verapamil had no effect on norepinephrine/epinephrine and norepinephrine/(norepinephrine+epinephrine) ratios in normal rats. Blockade of K+-channels in the medulla oblongata by local injection of 0.001 mg amiodarone did not change the levels of epinephrine and norepinephrine and norepinephrine/epinephrine and norepinephrine/(norepinephrine+epinephrine) ratios. In the medulla oblongata, verapamil proportionally increased the levels of norepinephrine, dopamine, and L-DOPA. Similarly, amiodarone increased the levels of L-DOPA and dopamine by 2.6 and 3.2 times, respectively. Amiodarone shifted the ratio of neuroactive amino acids towards inhibitory transmitters.