Abstract
Guanethidine in a concentration of 5×10-6 or 10-5 inhibited definitely the sweating axon reflex produced by the optimum concentration of nicotine (10-5); complete inhibition was always observed with guanethidine in 5×10-5. Likewise, the axon reflex response to the optimum concentration of acetylcholine (10-6) was always abolished by guanethidine in 5×10-5. Bretylium also suppressed the axon reflex response elicited by nicotine and acetylcholine: the inhibition was always complete with bretylium in 10-4 for nicotine, and with that in 5×10-4 for acetyl-choline.
In contrast, the sweating axon reflex elicited by the optimum concentration of NaCl (4×10-2) was affected neither by guanethidine nor by bretylium even at a concentration of 10-3.
The results suggest that guanethidine and bretylium belong to competitive blocking agents as far as the swaeting axon reflex is concerned.
