CHANGES OF RAT URINARY-BLADDER DURING ACUTE-PHASE OF SPINAL-CORD INJURY

Spinal cord injury (SCI) at Th13 was induced in female Wistar rats, an d changes in the urinary bladder were examined during the acute phase of SCI. Wet weights of the spinal bladders increased twofold over cont rols by 7 days after SCI. Intravesical volumes increased sixfold over control values by day 3, and then decreased 7 days after the injury. M aximal pressure within the bladder decreased in all spinal rats compar ed with controls. Smooth muscle cells were isolated from the urinary b ladder, and their total protein and DNA content were measured by multi parametric cytofluorometry. DNA content of isolated smooth muscle cell s decreased by day 3 and remained 7 days after the spinal injury. Tota l protein content of isolated smooth muscle cells was decreased 1 day after and increased 7 days after the spinal injury, just when spinal r eflex of the bladder recovered. These findings suggest that hypertroph y of smooth muscle cells in urinary bladder is related to the activity of peripheral autonomic nerve and that smooth muscle cells already be gin to hypertrophy during the spinal shock period to adjust themselves to the new state, that is, the spinal bladder.