Altered bladder function in transgenic mice expressing rat elastin

The elasticity of tissues subjected to repeated deformation is provided by the presence of elastic fibers in the extracellular matrix (ECM). The most abundant component of elastic fibers is elastin, whose soluble precursor is tropoelastin. To establish the role elastin plays in the bladder, this stu dy describes the biosynthetic, histologic, and physiologic consequences of expression of an isoform of rat tropoelastin in transgenic mouse bladder. T he polymerase chain reaction (PCR) was used to determine expression of a ra t tropoelastin minigene in transgenic mice. Histochemical methods were used to demonstrate changes in elastic fibers in frozen sections of bladder. Cy stometric analysis was carried out in transgenic and non-transgenic mice, p rior to and after 3 weeks of partial outlet obstruction. The PCR assay demo nstrated that bladder tissue of transgenic mice expressed rat tropoelastin mRNA, whereas non-transgenes did not. Increased deposition of elastic fiber s was demonstrated with the Verhoeff-van Gieson stain. Bladders of transgen ic animals were more compliant than bladders of their non-transgenic litter mates. Partial outlet obstruction resulted in increased bladder volume and more compliant bladders in non-transgenic mice. In contrast, the bladder vo lume and compliance in transgenes was almost unchanged by obstruction. This study demonstrates that normal elastic fiber assembly is prerequisite for the compliant properties of the bladder wall. Moreover, the response of the bladder to obstruction is critically influenced by elastin synthesis. Neur ourol. Urodynam. 18:55-68, 1999. (C) 1999 Wiley-Liss, Inc.