[An electromyographic study of the feline urethral rhabdosphincter in the normal state and after sacral rhizotomy. Part 1. Characteristics of action potentials of the rhabdosphincter and micturition and continence reflexes].

To investigate functional property of the urethral rhabdosphincter, the male feline rhabdosphincter was examined by means of electromyography using fine electrodes. Experiments were performed on 28 normal (N group) and 13 rhizotomized cats under chloralose anesthesia, the latter being further divided into two groups: 4 cats of 1-3 weeks (SR group) and 9 cats of 10-24 weeks (LR group) after complete sacral rhizotomy. Frequency of action potentials of the rhabdosphincter at empty bladder in N, SR and LR group was 1.8 +/- 0.3, 16.4 +/- 2.0, 8.9 +/- 1.4 spikes/sec, respectively, with significant difference between N and the other two groups and also between SR and LR group. Spontaneous discharges of the rhabdosphincter in SR and LR group were not abolished after neuromuscular junction blockade. The duration of action potentials of the rhabdosphincter in N, SR and LR group was 3.34 +/- 0.08, 1.71 +/- 0.07, 1.72 +/- 0.04 ms, respectively, with significant difference between N and the other two groups. Micturition reflex was negative in both SR and LR groups, but in 7 cats of LR group with dorsal roots preserved, activities of the rhabdosphincter increased reflexly by vesicourethral or urethrourethral contraction reflex, while they did not in 2 cats of LR group without preservation of dorsal roots and in SR group. Bulbocavernosus reflex was negative in both SR and LR groups.(ABSTRACT TRUNCATED AT 250 WORDS)