PROPERTIES OF CA2-MG2+ ATPASE IN RABBIT BLADDER MUSCLE AND MUCOSA - EFFECT OF URINARY OUTLET OBSTRUCTION()

The contractile response of the smooth muscle of the urinary bladder i s dependent upon both the entrance of extracellular calcium through re ceptor-operated calcium channels and the stimulated release of calcium from the sarcoplasmic reticulum. In addition, partial outlet obstruct ion induces marked alterations in the utilization of intracellular cal cium. Although calcium ATP-ase provides the energy for the translocati on of intracellular free calcium into storage sites within the sarcopl asmic reticulum, very little is known about the properties of this enz yme in bladder muscle and mucosa. As an initial study, divalent ion sp ecific ATP-ase activity was measured in extracts of rabbit bladder mus cle and mucosa from control animals and from rabbits following partial urinary outlet obstruction. In both normal bladder muscle and mucosa, magnesium and calcium ions were equally effective in activating the e nzyme. Seven days following partial urinary outlet obstruction, the AT P-ase activity in both bladder muscle and mucosa was significantly dep ressed by over 70%. The degree of the decreased enzyme activities obse rved within the muscularis and mucosa would indicate that specific mem brane functions supported by divalent-ion-ATP-ase are dysfunctional. T his hypothesis is supported by marked alterations in the utilization o f intracellular calcium following partial outlet obstruction and the m arked dysfunctions in both mucosal permeability and bacterial adherenc e to mucosa observed following partial outlet obstruction. (C) 1996 Wi ley-Liss, Inc.