OBJECTIVETo observe different effects of moxibustion on extracellular potassium ion in acupoint under physiological and pathological status and provide experimental evidence for exploring action mechanism of moxibustion on acupoint local.

METHODSForty female SD rats were randomly divided into a blank group, a blank-moxibustion group, a model group and a model-moxibustion group, 10 cases in each one. The complete Freund's adjuvant(CFA) was adopted to establish model of adjuvant arthritis (AA) in the model group and model-moxibustion group. No treatment was given in the blank group and model group while moxibustion was applied at "Zusan-li" (ST 36) for 30 min in the blank-moxibustion group and model-moxibustion group. The tissue fluid in "Zusanli" (ST 36) was collected with microdialysis and real-time analyzed by electrolytic analyzer. The change of concentration of potassium ion in "Zusanli" (ST 36) was observed.

RESULTS(1) Under physiological status, the concentration of extracellular potassium ion in the blank group was not changed within 150 min (P > 0.05); before the moxibustion, the concentration of extracellular potassium ion in the blank-moxibustion group was (1.21 +/- 0.31) mmol/L, and after treatment it was gradually increased and reached its peak at (2.38 +/- 0.42) mmol/L after 60 min (P < 0.05), then it was reduced. 150 min after the treatment, concentration of potassium ion was slightly higher than that before moxibustion as well as that in the blank group. The concentration in the blank-moxibustion group at 60 min was statistically significant compared with that in the blank group (P < 0.05). (2) Under pathological status, the concentration of extracellular potassium ion in the model group was not changed within 150 min, differences of which at each time point was not statistically significant (all P > 0.05). Before the moxibustion, the concentration of extracellular potassium ion was (1.09 +/- 0.12) mmol/L in the model-moxibustion group, and it was immediately increased to (1.96 +/- 0.18) mmol/L after moxibustion. 60 min and 90 min after the moxibustion, it still maintained a higher level, which was (1.87 +/- 0.29) mmol/L and (1.59 +/- 0.16) mmol/L respectively (both P < 0.05). The differences of each time point after moxibustion in the model-moxibustion group were statistically significant compared with those in the model group (all P < 0.05).

CONCLUSIONThe moxibustion could increase the concentration of potassium ion in rat's acupoint local under physiological status but time of effect is short; with moxibustion at "Zusanli" (ST 36) under pathological status, the concentration of local potassium ion is obviously increased and maintains for a long time.