Effect of Electroacupuncture on 99mTc-Sodium Pertechnetate Uptake and Extracellular Fluid Free Molecules in the Stomach in Acupoint ST36 and ST39

Abstract

Electroacupuncture (EA) is a therapeutic modality in which the electrical stimulation is integrated with concepts of acupuncture to treat diseases. This study was designed to evaluate the connection between the electro-acupuncture induced increase in Na^99mTcO4 uptake in the stomach wall, and the ionic molecule levels in the extracellular fluid in the acupoints. Wistar rats were treated by 2 or 100 Hz EA at Zusanli (ST 36) and Xiajuxu (ST 39) bilaterally for 60 minutes. The accumulation of Na^99mTcO4 in the gastric wall and the free ions, including Ca²⁺, K⁺, Na⁺, and Cl^-, in the acupoints were measured every 60 minutes. The radioactivity uptake in the stomach was significantly increased during EA, reaching peak at 180 minutes after the EA. The concentration of extracellular ions was also significantly increased during EA. The Ca²⁺ level continued to rise until 60 minutes after EA, then started to decrease at 120 minutes post-EA. The results suggest this up-regulatory effect of EA on gastric activity might be triggered by the increase of the extracellular ion levels, this effect lasts longer than stimulating the release of transmembrane Ca²⁺ flow alone. This might aid in providing a better understanding of the long-lasting effect claimed in acupuncture treatment.

Figure 1

Flow chart of our experiment.

Figure 2

Extracellular Ca²⁺ levels at acupoint ST 36 under electroacupunture. The Ca²⁺ level at acupoint ST 36 increased significantly during 2Hz-EA (p = 0.003 vs. pre-EA). The Ca²⁺ level continued to increase till 60 minutes after EA, and then started to decrease in post-EA at 120 minutes (p = 0.04 vs. EA). Similar to the situation under 2 Hz, the extracellular Ca²⁺ concentrations also increased significantly under high frequency (100 Hz) EA, and the increase started to decrease 120 minutes after EA. The difference between low and high frequencies (2 vs 100 Hz) did not reach significance. Compared with extracellular Ca²⁺ levels during EA, *p < 0.05, **p < 0.01, Two-way ANOVA followed by Duncan post hoc tests.

Figure 3

As compared with before EA group (A), the radioactivity uptake in the stomach was significantly increased during 2 Hz EA (B). The level of stomach Na^99mTcO4 uptake did not reached the peak until 180 min after EA (C), and then started to decrease 240 min after EA (D).

Figure 4

Compared with pre-EA, the radioactivity uptake in the stomach was significantly increased during 2 Hz-EA. The up-regulation escalated gradually and did not reach the peak until 180 minutes after the EA. The stomach uptake started to decrease 3 hours after 2 Hz EA at ST 36. 100 Hz-EA appeared to induce more radioactivity uptake than did 2 Hz EA in the stomach; however, no significance was reached in comparison of the two groups. Compared with radioactivity uptake in the stomach during EA, *p < 0.05, **p < 0.01, Two-way ANOVA followed by Duncan post hoc tests.