Bladder Smooth Muscle Strip Contractility as a Method to Evaluate Lower Urinary Tract Pharmacology

Abstract

We describe an in vitro method to measure bladder smooth muscle contractility, and its use for investigating physiological and pharmacological properties of the smooth muscle as well as changes induced by pathology. This method provides critical information for understanding bladder function while overcoming major methodological difficulties encountered in in vivo experiments, such as surgical and pharmacological manipulations that affect stability and survival of the preparations, the use of human tissue, and/or the use of expensive chemicals. It also provides a way to investigate the properties of each bladder component (i.e. smooth muscle, mucosa, nerves) in healthy and pathological conditions. The urinary bladder is removed from an anesthetized animal, placed in Krebs solution and cut into strips. Strips are placed into a chamber filled with warm Krebs solution. One end is attached to an isometric tension transducer to measure contraction force, the other end is attached to a fixed rod. Tissue is stimulated by directly adding compounds to the bath or by electric field stimulation electrodes that activate nerves, similar to triggering bladder contractions in vivo. We demonstrate the use of this method to evaluate spontaneous smooth muscle contractility during development and after an experimental spinal cord injury, the nature of neurotransmission (transmitters and receptors involved), factors involved in modulation of smooth muscle activity, the role of individual bladder components, and species and organ differences in response to pharmacological agents. Additionally, it could be used for investigating intracellular pathways involved in contraction and/or relaxation of the smooth muscle, drug structure-activity relationships and evaluation of transmitter release. The in vitro smooth muscle contractility method has been used extensively for over 50 years, and has provided data that significantly contributed to our understanding of bladder function as well as to pharmaceutical development of compounds currently used clinically for bladder management.

Functional and structural changes of the urinary bladder following spinal cord injury; treatment with alpha lipoic acid

“…These changes cause hyperreflexia following the acute areflexic phase. Recently, Kullmann et al 18 emphasized the need for functional studies of the detrusor muscle; and further suggested that data produced from these may contribute to the development of new treatment strategies for the clinical management of neurogenic bladder. 18 In an attempt to provide data on the functional, structural, and biochemical changes that occur in the urinary bladder following SCI, and to elucidate the possible therapeutic effect of LA on these parameters, we conducted the present study.…”

What are the origins and relevance of spontaneous bladder contractions? ICI‐RS 2017

“…Spontaneous contractions are most commonly recorded from strips of bladder wall, cut in longitudinal or circular orientation, with or without the mucosal layer (urothelium and lamina propria). Strips studied with in vitro myography 36 typically develop spontaneous activity during the equilibration phase after being mounted; this activity is typically maintained for several hours during experiments and is not blocked by neuromuscular transmitter receptor antagonists or the nerve blocker, tetrodotoxin, showing its myogenic origin. However, a problem with the use of bladder strips lies with the unique orientation of DSM 37 which does not form discrete layers as per gastro-intestinal or vascular smooth muscle, but comprises bundles of smooth muscle cells that apparently interlock with large spaces between bundles, facilitating expansion for urine storage.…”

Urinary Bladder-Relaxant Effect of Kurarinone Depending on Potentiation of Large-Conductance Ca2+-Activated K+ Channels

“…Isometric tension recording of UBSM experiments was conducted as previously described (dela Peña et al, 2009;Kullmann et al, 2014). Briefly, male Sprague-Dawley rats (300-350 g) were euthanized by CO 2 asphyxiation.…”