Purpose
 We assessed the effect of Electroacupuncture (EA) at Zusanli (ST36) acupoint on cardiac perfor-mance of spontaneously hypertensive rat (SHR), analyzing left ventricular pressure-volume (PV) relationship.
Methods
 SHR and Wistar-Kyoto rat (WKY) were anesthetized with isoflurane (1%). Conductance catheter (SPR-838, Millar instruments, Houston, Texas) was inserted into left ventricle via carotid artery. Steady state was maintained for at least 5 min before EA was started.
 EA stimulation point was set on the right anterior side of hindlimb, corresponding to Zusanli (ST36) acupoint in humans. SHR and WKY underwent EA stimulation in a frequency of 2Hz and intensity of 6mA with a pulse generator (Han’s Healthronics Likon, Taipei, Taiwan) for 15 min. PV relationship was measured at baseline, 10min after the start of EA stimulation and at 0, 5, 10, 15 min after the end, then analyzed to obtain parameters for cardiac performance.
Result
 In the basic state before EA stimulation, ESP, SW, PVA, Ea, dp/dtmax, dp/dtmin, Pmax, ESPVR and EDPVR in SHR was significantly higher than those in WKY(ESP, 109.6±8.3 vs. 175.0±14.6mmHg, p<0.01 ; SW, 5.7±1.6 vs. 8.8±3.7mmHg·ml, p<0.05 ; PVA, 11.7±4.0 vs. 19.3±6.4mmHg· ml, p<0.01 ; Ea, 1804.2±382.4 vs. 2625.3±629.3 mmHg/ml, p<0.01 ; dp/dtmax, 7512.9±1628.8 vs. 13406.3±1771.4mmHg/s, p<0.01 ; dp/dtmin, -7159.7±1236.8 vs. -12082.5±1280.2 mmHg/s, p<0.01 ; Pmax, 116.7±6.8 vs. 176.8±14.6mmHg, p<0.01 ; ESPVR, 1013.8±320.3 vs. 1520.1±494.8mmHg/ml, p<0.05 ; EDPVR 70.0±39.3 vs. 178.3±130.2 mmHg/ml, p<0.05, respectively), indicating increased systolic function and decreased diastolic function in SHR.
 Significant change in parameters of WKY could not be observed after EA stimulation. In SHR, ESP, EDP, Ea, dp/dtmax, dp/dtmin, Pmax was significantly decreased at 10 min after EA started. ESPVR was not significantly affected by EA in both WKY and SHR, however, ESPVR tended to be increased in WKY and decreased in SHR at 10min after the start of EA stimulation.
Conclusion
 EA decreased indicators of systolic function in SHR that is significantly higher than WKY. This study suggests that EA improved enhanced systolic function in SHR, compared with WKY.