Effect of ileocystoplasty on contractile response of the bladder,ileum, and cystoplastic ileal segment

Bladder augmentation or substitution with ileal segments is being used to a greater extent in recent years. The goal of the present study is to characterize the physiologic and pharmacologic changes in the ileal segment that occur following ileal cystoplasty. Four weeks following ileocystoplasty in rabbits, the contractile response of sections of normal terminal ileum, bladder body, and the cystoplastic segment of ileum (ileocystoplasty) was studied in isolated muscle baths. Results were as follows: 1) The ileum responded to a maximal dose of bethanechol with an increase in the amplitude and frequency of phasic contractions whereas the bladder displayed a rapid and sustained increase in basal tension. The cystoplastic ileal segment showed a marked increase in basal tension with superimposed phasic contractions. 2) Maximally effective doses of ATP and methoxamine reduced tension in the normal ileal segments but contracted both the bladder and cystoplastic ileal segments. 3) Isoproterenol reduced tension in all three segments. The pharmacological response of the cystoplastic segment of ileum significantly shifted from that of the ileum toward the response of the bladder. This effect is important as a manifestation of the functional plasticity of smooth muscle.