Detrusor muscle contractility and compliance are impacted by diet in Ossabaw miniature pigs with metabolic syndrome (MetS)

Abstract

The etiology of diabetic bladder dysfunction is not understood. Previous work suggests that MetS Ossabaw pigs have detrusor muscle that is stiffer than bladder muscle from lean pigs. The purpose of the current study was to determine if the loss of bladder muscle compliance is exacerbated in pigs manifesting robust MetS. Detrusor muscle strips from Ossabaw pigs maintained on either an excess kcal atherogenic diet or a control diet were mounted initially at slack length in muscle baths. Following equilibration, muscle strips were stimulated with supramaximal electrical field stimulation (EFS: 20 V, 60 Hz, AC, 10 sec). Following relaxation, strips were stretched in 0.5–1.5 mm increments. The cycles of incremental stretches followed by EFS‐induced contractions were repeated every 5 minutes until maximum total tension was achieved or the tissue yielded. Normalized passive and active length‐tension (L‐T) curves were generated. Due to small sample sizes (n=3/group), no statistical analyses are reported. However, both mean passive and active L‐T curves for bladder muscle from MetS pigs are elevated above the respective control curves indicating that MetS results in increased contractility in addition to decreased compliance of the bladder muscle. Stiffer bladders that are hypercontractile could explain both the incomplete voiding and increased urinary frequency experienced in diabetes which is characteristic of metabolic syndrome.(R Sharma is an APS Undergraduate Summer Research Fellow; B Harden was an Indy Project Seed Scholar; Support: NIH RR013223, HL062552)