EFFECTS OF NALOXONE ON REGIONAL NOREPINEPHRINE CONTENT OF THE RABBIT URINARY-BLADDER AFTER ELECTRICAL PELVIC FLOOR SIMULATION

Objectives. Effect of opioid blockade on regional norepinephrine conte nt of the rabbit urinary bladder was investigated under electrical pel vic floor stimulation. Methods. Norepinephrine content of the bladder body and base of the rabbit was estimated by high-performance liquid c hromatography in the following four subgroups: control group; group 1, treated by electrical stimulation; group 2, treated by naloxone alone ; and group 3, treated by electrical stimulation and naloxone. Results . Intravenous administration of naloxone (group 2) caused depletion of norepinephrine content in the bladder body (P < 0.001). Norepinephrin e content in the bladder base was also reduced, although this differen ce was not statistically significant. Electrical stimulation to the pe lvic floor musculature (group 1) increased norepinephrine content both in the bladder base and the body (P < 0.01). Such a norepinephrine el evation disappeared in the rabbit treated by electrical stimulation pl us naloxone (group 3). Norepinephrine content of this group was almost the same as those treated by naloxone alone. Conclusions. Opioid bloc kade appeared to block the hypogastric nerve activation induced by ele ctrical pelvic floor stimulation.