EFFECT OF SUCCINYLCHOLINE, DIAZEPAM, AND DANTROLENE ON THE URETHRAL PRESSURE PROFILE OF ANESTHETIZED, HEALTHY, SEXUALLY INTACT MALE CATS

Effects of the neuromuscular blocking agent succinylcholine (n = 9), t he centrally acting skeletal muscle relaxant diazepam (n = 11), and th e direct-acting skeletal muscle relaxant dantrolene sodium (n = 8) on the urethral pressure profile were evaluated in anesthetized, healthy, sexually intact, adult male cats. Intravenous administration of succi nylcholine (0.075 mg/kg of body weight) significantly decreased mean a bsolute pressure in the prostatic and postprostatic/penile intraurethr al segments by -9.5 and -6.5 mm of Hg, respectively (P = 0.0002 and P = 0.0006, respectively). Dantrolene (1.0 mg/kg, IV) significantly decr eased mean prostatic and postprostatic/penile intraurethral segmental pressures by -3.5 and -2.8 mm of Hg, respectively (P = 0.005 and P = 0 .0181, respectively). Diazepam (0.8 mg/kg, IV) did not significantly a lter mean intrauethral, segmental pressures. None of the drugs caused a change in segmental lengths of the urethra. These results indicate t hat skeletal muscle makes a substantial contribution to intraurethral tone in anesthetized, healthy sexually intact male cats and that skele tal muscle relaxation may be successful in reducing prostatic and post prostatic/penile urethral segmental tone in male cats. These results a lso suggest: that dantrolene sodium may be valuable for the pharmacolo gic management of urethral disorders in male cats.