Objective: To investigate the efficacy of intravesical liposomes against dimethyl sulphoxide (DMSO), and pentosan polysulphate (PPS) in reducing chemically induced bladder hyperactivity in rats.
Materials and methods: Bladder reflex activity of female Sprague-Dawley rats was evaluated by continuous cystometry under urethane anaesthesia (1.0 g/kg). After obtaining a control cystometrogram (CMG) with normal saline (0.04 mL/min) for 2 h, bladder hyperactivity was then induced by 1 h infusion of protamine sulphate (10 mg/mL) followed by a 1-h infusion of KCl (500 mm). Six rats each were then infused with KCl-based preparations containing either 50% DMSO, PPS (6 mg/mL), or liposomes (2 mg/mL) for 2 h. The variables measured included the intercontraction interval (ICI), pressure threshold (PT) and baseline pressure (BP).
Results: Sequential infusion of protamine sulphate/KCl induced hyperactive bladder with no significant difference in ICI, PT or BP among groups before initiating treatment. ICI was significantly increased after infusion of PPS (58.1% increase) and liposomes (156.8% increase) but there was no increase with DMSO. PT was not significantly affected by liposome infusion but slightly increased with PPS (12.4% increase). There was a large and significant increase in PT and BP with DMSO (116.5% increase) and BP largely remained unchanged after instillation with liposomes or PPS.
Conclusions: Intravesical liposomes and PPS have a beneficial effect in a bladder hyperactivity rat model, while acute instillation of DMSO does not. Intravesical liposomes were effective in doubling the ICI compared with PPS, and might be a new treatment option for bladder hyperactivity.