Instillation of liposomes vs dimethyl sulphoxide or pentosan polysulphate for reducing bladder hyperactivity

Abstract

To investigate the efficacy of intravesical liposomes against dimethyl sulphoxide (DMSO), and pentosan polysulphate (PPS) in reducing chemically induced bladder hyperactivity in rats. 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). 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. 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.