system
Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Animals, Electric Stimulation, Guinea Pigs, Male, Muscle Relaxation, Muscle, Skeletal, Nitric Oxide, Urethra.
user
Is urethral relaxation after electrostimulation in the guinea pig independent of nitric oxide? Context: To investigate whether the relaxation of the striated urethral sphincter in guinea pigs is mediated by nitric oxide. After sacrifice, urethral rings were cut between the bladder neck and the penile crura and mounted in an in vitro bath. Maximal isometric tension obtained at 1, 3, 10 and 25 Hz electrical stimulation (Tmax) for 5 to 30 sec was measured. Tmax at 25 Hz was not changed by pretreatment with 10(-4)M nitroprusside or 10(-4)M NG-nitro-L-arginine. In urethral tissue precontracted with 10(-4)M noradrenaline, a significant relaxation of 16-25% was found at 10 Hz. This relaxation could not be prevented by pretreatment with 10(-4)M NG-nitro-L-arginine and was not enhanced by the presence of 10(-3)M L-arginine.
assistant
Noradrenaline-precontracted urethral rings of male guinea pigs exhibit a maximal relaxation at 10 Hz, which does not depend on nitric oxide. Final Decision: yes