Growth resistance-sized arteries in response to bladder hypertrophy in the rat: Time-course, DNA-synthesis and LDH-isoform pattern

Bladder growth was induced by partial urethral obstruction. Bladder hypertrophy was evident at 53 h after obstruction and continued over a 6 weeks period, Small bladder arteries were taken from fixed anatomical locations of the bladder circulation. mounted in a small vessel myograph and the optimal diameter for maximal isometric force development was determined (L(max), K+ = 125 mM stimulation). Bladder hypertrophy was associated with an enlarged L(max) from 53 h onward (compared with sham-operated controls) and L(max) continued to increase until 10 days after urethral obstruction. Between 10 days and 6 weeks no further increase of the diameter was observed. Increased diameters in vitro were accompanied by a transiently increased [H-3]Thymidine uptake in the small arteries which peaked al 53 h after obstruction but was still above background at 10 days. At this time point. small arterial growth was associated with a significant relative increase in the M isoform of LDH as determined with agarose electrophoresis on tissue homogenates. Thus organ growth induced small vessel growth in the rat is characterized by a rapid onset, increased but transient DNA-turnover and LDH-isoform changes. The latter mimic changes seen in other types of smooth muscle growth.