THE EFFECT OF ANOXIA AND GLUCOSE-FREE SOLUTIONS ON THE CONTRACTILE RESPONSE OF GUINEA-PIG DETRUSOR STRIPS TO INTRINSIC NERVE-STIMULATION AND THE APPLICATION OF EXCITATORY AGONISTS

Purpose: To study the effects of anoxia and substrate depletion, both separately and combined, on the contractile responses of guinea-pig de trusor smooth muscle strips to activation of intrinsic nerves, applica tion of agonists and depolarization with high potassium solution. Mate rials and Methods: Bladders were opened and the urothelium removed. St rips of detrusor were dissected and mounted for tension recording in s mall organ baths superfused with warmed solutions of known composition . Results: Anoxia caused a small initial reduction of the contractile responses which then remained constant for several hours. Glucose-free solutions resulted in a slow progressive decline in the responses to field stimulation, carbachol and high potassium solution, with substan tial responses still present after five hours. The response to ATP, ho wever, was unaffected. Removal of oxygen and glucose, mimicking ischae mia, caused abolition of all responses within an hour. After reintrodu ction of normal conditions responses reached their maximal extent of r ecovery within an hour. Recovery was almost complete for responses to ATP and carbachol, but less so for high K+ solutions. Very little reco very to stimulation of intrinsic nerves was seen. Conclusions: The res ults demonstrate that phasic contractions can be fuelled almost fully by oxidative phosphorylation or by anaerobic glycolysis, but that in c onditions mimicking ischaemia the intrinsic nerves are more susceptibl e to ischaemic damage than the detrusor smooth muscle.