title: The effects of cellular hypoxia on contraction and extracellular ion accumulation in isolated human detrusor smooth muscle.
abstract: OBJECTIVE
  The effect of cellular hypoxia on the phasic isometric contraction of isolated preparations of human detrusor muscle was measured and the influence of the accumulation of extracellular H+ and K+ on the inotropic effects ascertained.
  
  
  METHODS
  Strips of human detrusor smooth muscle were field stimulated and superfused with an HCO3-/CO2 medium. Cellular hypoxia was generated by superfusion with 1) a low PO2 (approximately 5 kPa) solution; 2) 5 mM. Na azide; or 3) 10 mM. 2-deoxyglucose and omission of glucose and Na pyruvate. Extracellular pH or [K+] was simultaneously measured with ion-selective microelectrodes placed in the muscle strip.
  
  
  RESULTS
  Interventions produced a reversible contractile decay in the steady state, but the decay was preceded by a transient increase of force in most preparations. A small rise of the extracellular [K+] was also measured, but the effect was significantly smaller with 2-deoxyglucose. Extracellular acidosis was recorded with low PO2 and Na azide, but was absent with 2-deoxyglucose. The extracellular acidosis was usually preceded by a transient extracellular alkalosis.
  
  
  CONCLUSIONS
  Part of the contractile changes under these conditions could result from an extracellular acidosis generated via glycolysis; the accumulation of extracellular K+ was insufficient to exert inotropic effects.
authors.affiliation: Institute of Urology and Nephrology, University College London, United Kingdom.
authors.forename: P J
authors.initials: PJ
authors.lastname: Thomas
authors.forename: C H
authors.initials: CH
authors.lastname: Fry
mesh_terms: D001386:Azides / Q000494:pharmacology; D015687:Cell Hypoxia; D005110:Extracellular Space / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D001743:Urinary Bladder / Q000378:metabolism*
chemical_list: D001386:Azides; D011188:Potassium