Effect of DHLA on response of isolated rat urinary bladder to repetitive field stimulation

Lipoic acid is an essential coenzyme in the oxidation of pyruvate and alpha-ketoglutarate. It is easily converted to its reduced form, dihydrolipoic acid (DHLA), in vivo thereby forming a redox pair. DHLA is important in the maintenance and integrity of specific neuronal and subcellular membranes. In the present study we investigated the effect of DHLA on the response of isolated rat bladder strips to repetitive field stimulation (FS), a method used to exhaust synaptic stores of acetylcholine resulting in nerve and synaptic damage. Isolated strips of rat urinary bladders were separated into 4 groups. Group 1 strips were incubated with choline + acetyl-CoA; Group 2 strips with choline, acetyl-CoA + DHLA; and Group 3 with DHLA. Group 4 strips were controls. All strips in Groups 1-3 were subjected to 2 h of repetitive FS followed by 2 h of recovery. DHLA had no effect on the progressive decrease in contractile response observed during repetitive stimulation. However, strips incubated in the presence of DHLA showed a significantly greater degree of recovery than strips incubated in the absence of DHLA. We believe that the protection of the contractile response is related to DHLA's ability to protect nerve and/or muscle membranes from oxidative damage.