Female pig urethral tone is dependent on Rho guanosine triphosphatases and Rho-associated kinase

Ulf Malmqvist, Petter Hedlund, Karl Swärd, Karl Erik Andersson

Research output: Contribution to journalArticlepeer-review


Purpose: Circular smooth muscle of the urethra generates spontaneous myogenic tone of relevance for the maintenance of continence. We tested if Rho guanosine triphosphatases (GTPases) and Rho-associated kinase (ROK) are involved in the generation of urethral tone. Materials and Methods: Small circular strips of female pig urethra were dissected out and mounted for recording isometric force. The effect of pharmacological agents known to modulate the activity of Rho GTPases or ROK was examined. The intracellular calcium concentration was measured using fura-2. Results: Urethral tone was abolished by removing extracellular calcium or by adding the calcium antagonist felodipine. The decrease in force was closely related to a decrease in intra-cellular calcium concentration, indicating that tone depends on membrane associated mechanisms. Toxin B, which inactivates Rho GTPases, and Y 27632, which inhibits ROK, completely abolished tone in the female pig urethra. The latter effect occurred without any change in the intracellular calcium concentration. Conclusions: The results suggests that urethral tone depends on activity in G-protein coupled pathways and inhibition of this activity is sufficient for urethral tone relaxation. Thus, to our knowledge a new pathway in the generation of urethral tone, which might be acted on by autonomic nerves during micturition, has been identified.

Original languageEnglish
Pages (from-to)1955-1958
Number of pages4
JournalJournal of Urology
Issue number5
Publication statusPublished - May 2004


  • GTP-binding proteins
  • Muscle, smooth
  • Rho-associated kinase
  • Swine
  • Urethra

ASJC Scopus subject areas

  • Urology


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