Introduction:
There are two types of phenylalanine, one of the essential amino acids, D-Type and L-type. Phenylalanine in itself has shown no clear analgesic effect in human beings, however, as we reported previously, D-type phenylalanine (DPA) when administered prior to acupuncture analgesia in human beings lengthens the analgesic effects of acupuncture. At this time then, using volunteers in whom acupuncture analgesia failed to raise the pain threshold (PT) we experimentally studied whether or not DPA has any influence.
Methods:
Subjects were divided into an acupuncture anesthesia effective group (a rise in PT was observed due to acupuncture) and an acpuncture anesthesia ineffective group (no rise in PT). 4.0g. DPA was administered orally in both groups 30 minutes prior to acupuncture anesthesia. For acupuncture anesthesia right and left LI-4 and right and left ST-36 were used with low frequency electric current administered for 50 minutes. For the determination of PT a radiant heat pain meter was used. The PT was measured when DPA was administered, during acupuncture anesthesia and at every 30 minutes for 3 hours after the needles were withdrawn.
Results:
In the acupuncture anesthesia effective group, a rise in the PT was observed in 4 of the 5 cases and, the rise was much faster than when acupuncture anesthesia was used alone. In the acupuncture anethesia ineffective group, there were cases in which a remarkable rise in PT was observed or in which no rise in the PT occured during acupuncture stimulation but occured after the discontinuation of the acupuncture and some cases in which no rise occured during or after anesthesia.
Discussion:
1. In the acupuncture anesthesia effective group due to DPA pre-medication, the rate of PT rise quickened.
2. After operations the PT rise was lengthened.
3. The individuality of the acupuncture effectiveness in human beings was partially eliminated.