Abstract
BackgroundThe reaction of the corpora cavernosa (CC), the corpus spongiosum (CS), the bulbocavernosus (BCM) and ischiocavernosus (ICM) muscles to passage of urine through the urethra during micturition is not known. We investigated the hypothesis that the passage of urine through the urethra stimulates the corporal tissue and cavernosus muscles.MethodsIn 30 healthy men (mean age 42.8 ± 11.7 years), the electromyographic activity (EMG) of the CC, CS, BCM, and ICM were recorded before and during micturition, and on interruption of and straining during micturition. These tests were repeated after individual anesthetization of urethra, corporal tissue, and cavernosus muscles.ResultsDuring micturition, the slow wave variables (frequency, amplitude, conduction velocity) of the CC and CS decreased while the motor unit action potentials of the BCM and ICM increased; these EMG changes were mild and returned to the basal values on interruption or termination of micturition. Micturition after individual anesthetization of urethra, corporal tissue and cavernosal muscles did not effect significant EMG changes in these structures, while saline administration produced changes similar to those occurring before saline administration.ConclusionThe decrease of sinusoidal and increase of cavernosus muscles' EMG activity during micturition apparently denotes sinusoidal relaxation and cavernosus muscles contraction. Sinusoidal muscle relaxation and cavernosus muscles contraction upon micturition are suggested to be mediated through a 'urethro-corporocavernosal reflex'. These sinusoidal and cavernosus muscle changes appear to produce a mild degree of penile tumescence and stretch which might assist in urinary flow during micturition.
Highlights
The reaction of the corpora cavernosa (CC), the corpus spongiosum (CS), the bulbocavernosus (BCM) and ischiocavernosus (ICM) muscles to passage of urine through the urethra during micturition is not known
Electrocavernosogram of the CC and CS Basal slow waves (SWs) were recorded from the electrodes applied to the CC and CS
The smooth muscles surrounding the corporal sinusoids showed in the flaccid phase, a high basal electromyographic activity (EMG) activity indicating that they were in a contracted state [16,17,18,19,20]
Summary
The reaction of the corpora cavernosa (CC), the corpus spongiosum (CS), the bulbocavernosus (BCM) and ischiocavernosus (ICM) muscles to passage of urine through the urethra during micturition is not known. We investigated the hypothesis that the passage of urine through the urethra stimulates the corporal tissue and cavernosus muscles. The mechanism of micturition is intricate and under the control of reflex and voluntary actions [1,2,3,4,5,6,7]. The sinusoids of the corpora cavernosa (CC) and corpus spongiosum (CS) of the penis are contracted and contain a minimal amount of blood in the flaccid phase, while they relax and are full of blood during erection. The bulbo- and ischio-cavernosus muscles (BCM, ICM) contract in the rigid erectile phase [13,14]. The recording of the electric activity of the corporal tissue (CC, CS) was introduced by Wagner and Gerstenberg in 1989 [15] and later studied by other investigators [16,17,18,19,20]
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