The significance of smooth and striated muscles in the sphincter function of the urethra in healthy women

Thind, Peter

doi:10.1002/nau.1930140602

Cited by 63 publications

(47 citation statements)

References 144 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In the pig, the striated muscle plays little role in generating the resting pressure profile of the urethra (Bridgewater et al 1993;Greenland et al 1996) since the striated muscle is distal to the high pressure zone, and neuromuscular blockade has little effect on the peak urethral pressure. In the human, however, elimination of striated muscle tone causes a marked reduction in peak urethral pressure (for review see Thind, 1995), and most authors believe that urethral striated muscle contributes significantly to resting urethral pressure. This is supported by the EMG studies described above (Fowler & Fowler, 1987).…”

Section: Striated Musclementioning

confidence: 99%

“…In this species, provided the blood pressure is maintained, blockade of a-adrenoceptors reduces the urethral pressure (Macneil et al 1991) but does not abolish it, suggesting that the myogenic tone of the urethral smooth muscle also contributes to the resting pressure. In humans, in vivo studies of the effects on urethral pressure of administration of cholinoceptor and adrenoceptor agonists and antagonists have had variable results, but suggest that there is a tonic effect of the sympathetic system, whereas cholinergic stimulation has little effect on intraurethral pressure (Thind, 1995). The variability of the results may stem from the fact that systemically applied drugs will affect both the longitudinal and the circular smooth muscles, and these may have opposite effects on the urethral pressure.…”

Section: Smooth Musclementioning

confidence: 99%

See 1 more Smart Citation

The physiology of the mammalian urinary outflow tract

Brading¹

1999

Experimental Physiology

View full text Add to dashboard Cite

SUMMARYUrinary outflow from the mammalian bladder occurs through the urethra. This outflow tract is a complicated structure composed of striated and smooth muscle and vascular urothelium. It is controlled by somatic and autonomic nerves and has several functions: it generates sustained tone to prevent urinary leakage during bladder filling; it generates transient reflex increases in pressure to prevent opening of the .lumen when abdominal pressure rises; it undergoes relaxation preceding micturition and can generate urethral opening and shortening during micturition. A urethral pressure profile shows a peak pressure of 2 100 cmH,O. The outermost coat is striated muscle, the striated or external sphincter. The fibres are predominantly circularly oriented. The extent varies in different species and between sexes. In the human female it extends the length of the urethra, and is composed mainly of slow twitch fibres. In the male, the sphincter extends from the membranous urethra over the base of the prostate and has nearly equal numbers of slow and fast twitch fibres. In both sexes, the posterior border may be deficient in striated muscle, and filled by circularly oriented smooth muscle. Activity in the slow twitch fibres through somatic nerves may be continuous during bladder filling. Outer circular and inner longitudinal smooth muscle is present Strips from either layer will generate sustained tone particularly if dissected from the high pressure zone. This tone is myogenic, and may be achieved in the absence of action potentials, but relies on influx of calcium through L-type calcium channels. Both layers receive sympathetic and parasympathetic excitatory innervation and nitrergic inhibitory innervation. Normal urethral pressure requires blood flow to the urothelium (lamina propria). Striated and smooth muscles are both thought to contribute to the resting urethral pressure in the human. The precise role of the smooth muscles during micturition is as yet unresolved. INTRODUCTIONThe urethra, which connects the bladder to the exterior, is a highly complex organ. This is true whether one considers its function, its structure or the mechanisms involved in its control, and it applies both to the male and the female. Nevertheless the majority of normal humans are probably totally unaware of the complexities of the system. However, when something goes wrong, the importance of a perfectly functioning outflow tract is immediately apparent, and the considerable difficulties both for the patient and the clinician in improving the function lead to an appreciation of just how complex the system is, and how little we really understand it.*

show abstract

Section: Striated Musclementioning

confidence: 99%

Section: Smooth Musclementioning

confidence: 99%

The physiology of the mammalian urinary outflow tract

Brading¹

1999

Experimental Physiology

View full text Add to dashboard Cite

show abstract

“…[1][2][3][4] Urethral pressure reflectometry (UPR) is a novel technique for simultaneous measurements of pressure and CA in the female urethra. 3 The technique only involves the insertion of a very thin plastic bag.…”

Section: Introductionmentioning

confidence: 99%

Urethral pressure reflectometry and pressure profilometry in healthy volunteers and stress urinary incontinent women

Klarskov

Lose

2008

Neurourology and Urodynamics

View full text Add to dashboard Cite

show abstract

“…Such experiments have been carried out in normal humans, mostly women, and the results described and discussed in an excellent review [1]. To summarise, systemic administration of noradrenaline has relatively little effect on the urethral pressure, and α 1 -adrenoceptor antagonists such as prazosin usually result in a small but significant drop in the maximal urethral pressure.…”

Section: Storage Of Urinementioning

confidence: 99%

“…There remains the question in the human as to the role of the striated muscle in generating urethral pressure. Most experiments suggest that unlike the pig, neuromuscular blocking drugs do substantially reduce urethral pressure, although they do not abolish it [1]. Continuous electromyographic activity can be recorded during filling in human subjects [8]supporting a role of the urethral striated muscle during filling.…”

Section: Storage Of Urinementioning

confidence: 99%