ELASTIC WALL PROPERTIES AND COLLAGEN CONTENT IN THE URETER - AN EXPERIMENTAL-STUDY IN PIGS

We used an impedance planimetric method to look at elastic wall proper ties of ureter in ten anaesthetized pigs. A balloon was stepwise infla ted and deflated in the ureteropelvine junction, in the mid-ureter, an d in the intramural part of the ureter at the ureterovesical junction with pressures up to 70 cmH2O, while the pressure and balloon cross-se ctional area (Bcsa) were measured simultaneously. The elastic wall par ameters were calculated from these measurements. At sacrifice, tissue samples were collected for analysis of collagen content of the uretera l wall. A non-linear clockwise relation (hysteresis loops) between Bcs a and balloon pressure was demonstrated. At maximal inflation of the b alloon, the Bcsa, wall tension, and compliance were 35.28 +/- 3.52, 38 .44 +/- 3.23, and 61.36 +/- 8.09 MM2, 230.71 +/- 12.82, 242.38 +/- 10. 49, and 302.17 +/- 20.03 cmH2O x m, and 0.167 +/- 0.047, 0.124 +/- 0.0 02, and 0.182 +/- 0.040 mm2 X cmH2O-1 in the intramural part of the ur eter, middle part, and ureteropelvine junction, respectively. The coll agen content was 0.3249 +/- 0.0077, 0.3301 +/- 0.0066, and 0.3457 +/- 0.0060 mg x mg-1 dry defatted weight in the intramural part, in the mi ddle, and in the ureteropelvine junction, respectively. The collagen c ontent of the ureteropelvine junction was significantly higher than th at of the middle of ureter (P < 0.02) and than that of the intramural part (P < 0.05). No significant correlations were found between the el astic parameters at maximal inflation of the balloon and the collagen content (P > 0.10). In conclusion the elastic wall properties were sig nificantly different in the three ureteral segments and the collagen c ontent of the ureteropelvine junction differed from that of the two di stal locations. However, no relationship between the wall properties a nd the collagen content was found. (C) 1994 Wiley-Liss, Inc.