EFFECT OF PARTIAL OUTLET OBSTRUCTION OF THE RABBIT URINARY-BLADDER ONRYANODINE BINDING TO MICROSOMAL-MEMBRANES

1. Partial outlet of obstruction of the rabbit urinary bladder results in a significant increase in the ability of ryanodine to inhibit fiel d stimulated contraction. The current study determined the effect of o utlet obstruction on ryanodine binding to microsomal membranes. 2. The results demonstrate: (i) Ryanodine binding is linear showing one set of ryanodine binding sites (B-max = 28 +/- 3.5 fmol/mg protein; K-d = 4.2 nM). (ii) Total ryanodine binding was slightly increased at 1 and 3 day following obstruction. (iii) Binding increased approx 4-fold at 5 and 7 days post obstruction. (iv) No change in the K(d)s were noted at any time period. 3. The results of these studies indicate that smoo th muscle hypertrophy secondary to partial outlet obstruction induces a marked increase in the role of intracellular calcium in the mediatio n of the contractile response to field stimulation.