Objective To investigate the contributions of nitric oxide (NO) and prostaglandins (PGs) to the increase in local muscle blood flow (MBF) observed following manual acupuncture (MA). Methods Male Sprague-Dawley rats (n=112; 250-310 g) were injected intraperitoneally with a non-selective NO synthase inhibitor (NG-nitro-Larginine methyl ester hydrochloride: L-NAME; 10, 50 or 500 mg/kg), a non-selective cyclooxygenase inhibitor (indomethacin; 10, 50 or 500 mg/kg), a combination of L-NAME and indomethacin (500 mg/kg each) or saline only under urethane anaesthesia (1.2 g/kg). We used the sparrow pecking technique for 1 min with a stainless steel acupuncture needle (0.20×30 mm) as the acupuncture stimulation method. The stimulus point was on the right tibialis anterior muscle.
51Chromium-labelled microspheres were used for MBF measurement. Results MA increased MBF in the saline-injected group ( p<0.001). This increase was partially inhibited by L-NAME in a dose-dependent manner ( p>0.05, p<0.05 and p<0.001 for 10, 50 and 500 mg/kg, respectively). On the other hand, indomethacin did not suppress the increase ( p>0.05 each for 10, 50 and 500 mg/kg). No significant difference was observed between the inhibitory effects of combined administration of L-NAME and indomethacin and single administration of L-NAME ( p>0.05). Conclusions These results suggest that NO is a major factor in the MA-induced increase in MBF, while PGs do not contribute significantly to this increase. As complete inhibition was not achieved by administration of L-NAME±indomethacin, it appears that non-NO and non-PG vasodilators are additionally involved.
BACKGROUNDAcupuncture induces analgesia and functional improvement in various types of