Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
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The lower urinary tract is a complex system of smooth muscles and skeletal muscles which act together to ensure continence in rest and under stress conditions (Fig. 1).

Fig. 1: 3D model of the lower urinary tract of the human. Only muscles which are common in both sexes are shown. (1) M. detrusor vesicae, (2) M. sphincter vesicae, (3) M. sphincter urethrae glaber, (4) M. sphincter urethrae transversostriatus, (5) urethra, (6) M. dilatator urethrae.

The tonus of the smooth urethral sphincter (3) provides continence in rest, while in stress the striated part of the external sphincter (4) contracts by a spinal reflex. In the male the internal sphincter (2) prevents retrograde ejaculation. The longitudinal smooth muscle at the ventral urethra (6) is supposed to have the function of opening the urethra and the internal muscle (2) during micturition.

These complex functions are coordinated via sympathetic, parasympathetic and NANC-innervation of the different muscles. The objective of our investigations was to characterize the physiological properties and signal transduction in the different smooth muscles of the lower urinary tract at a cellular basis.

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