sympathoexcitatory reflexes during electroacupuncture in cats. Am J

puncture (EA) causes prolonged suppression of reflex elevations in blood pressure for 1–2 h in anesthetized preparations. A long-loop pathway involving the arcuate nucleus (ARC), ventrolateral periaq-ueductal gray, and rostral ventrolateral medulla (rVLM) is involved in sympathoinhibitory cardiovascular EA effects. However, the mecha-nisms and locations of the prolonged EA inhibition are unknown. We hypothesized that this effect is mediated through a long-loop pathway involving opioid, nociceptin, and -aminobutyric acid (GABA) re-ceptor activation in the rVLM. In anesthetized, ventilated cats appli-cation of bradykinin to the gallbladder every 10 min induced consis-tent reflex increases in blood pressure. Bilateral EA stimulation at the cardiovascular acupoints P5–6 overlying the median nerves reduced the reflex responses for at least 80 min. Bilateral blockade with kynurenic acid in the ARC 60 min after onset of EA inhibition reversed the cardiovascular response, suggesting a role for the ARC i