LOW AND HIGH-FREQUENCY ELECTROACUPUNCTURE AT HOKU ELICITS A DISTINCT MECHANISM TO ACTIVATE SYMPATHETIC NERVOUS-SYSTEM IN ANESTHETIZED RATS

To address the effect of electroacupuncture (Ea) on autonomic nerve ac tivity, the responses of rhythmic micturition contraction (RMC), urine excretion (UE), blood pressure (BP), renal sympathetic nerve activity (RNA) and pelvic parasympathetic nerve activity (PNA) to Ea were inve stigated in urethane-anesthetized rats. The acupoint Hoku (Li-4) was t ested with two different stimulation frequencies (2 Hz and 20 Hz). Elo ngation of the RMC cycle and an increase in UE associated with the ele vation of BP and RNA was elicited during Ea at Hoku. However, the pres ser response induced by low frequency Ea (LFEa) was different from tha t by high frequency Ea (HFEa), i.e. a tonic effect was elicited by LFE a, while a phasic one was induced by HFEa. These results imply that: ( 1) Ea at Hoku may selectively activate the sympathetic, but not the pa rasympathetic nervous system, (2) Ea at Hoku with a different stimulat ion frequency may elicit a distinct mechanism to activate the sympathe tic nervous system and (3) Ea at Hoku may ameliorate the hyperactive b ladder in clinical therapy. (C) 1998 Published by Elsevier Science Ire land Ltd.