Pressor effects on blood pressure induced by isovolumic bladder distension and electro-acupuncture stimulations in anesthetized rats.

The pressor effects on blood pressure (BP) elicited by electro-acupuncture (Ea) stimulations and vesico-vascular reflex (VVR) were investigated in anesthetized rats. Twenty adult female Sprague-Dawley rats were used throughout this study. Two acupoints, the Hoku (Li-4) and the Tsusanli (St-36), were tested by a low frequency Ea (LFEa, 2 Hz) and a high frequency Ea (HFEa, 20 Hz) with intensities 20 times that of the motor threshold. Ea at Tsusanli elicited no pressor effects (98.15 +/- 4.10% and 101.43 +/- 3.96% of pre-stimulation control in LFEa and HFEa, respectively) whereas pressor effects could be induced by Ea stimulations at Hoku (126.3 +/- 3.3% and 136.3 +/- 3.8% of pre-stimulation control in LFEa and HFEa, respectively, P < 0.01, n=10). In addition, the patterns of pressor effects elicited by LFEa and HFEa at Hoku were different, i.e., LFEa at Hoku elicited a tonic pressor effect, while HFEa elicited a phasic one. The VVR induced by bladder isovolumic saline distension also elicited a pressor effect on BP (119.2 +/- 2.2%, P < 0.01, n=10) in the same preparations during bladder contractions. The VVR did not modify the Ea-induced pressor responses, and vice versa, when both of them were superimposed. All the results suggested that the pressor effects elicited by the VVR and the Ea stimulation were additive responses. In addition, for future clinical application, our findings may imply that patients should be carefully monitored for signs and symptoms of autonomic dysfunction during clinical acupuncture treatments.