EXPERIMENTAL STUDIES ON THE NEUROGENIC BLADDER

XVIII. On the contraction response of the urinary bladder evoked by electro-stimulation of the ventral rami of the lower lumbar nerves in the dog

Abstract

To clarify the physiological innervation of the lower lumbar spinal cord to the urinary bladder of the dog, a selective electro-stimulation (monophasic, 5V, 2msec, 10Hz, 5sec) of the ventral rami of the L_5.6.7 lumbar nerves was performed, and the change of the intravesical pressure, as a response of the bladder to the stimulus, was observed with the isometric cystometry technique.
In addition, various nervous pathways to the urinary bladder from the lower spinal cord, including the ventral rami of the L_5.6.7 lumbar nerves, were cut off systematically, and its effects on the vesical response were examined.
The results obtained were as follows:
1. The selective electro-stimulation of each of the ventral rami of the L_5.6.7 lumbar nerves evoked vesical contraction response.
2 a The selective centrifugal electro-stimulation of the ventral rami of the L_5.6.7 lumbar nerves, which had been severed proximally produced no vesical response. But the selective centripetal electrostimulation of the ventral rami of the L_5.6.7 lumbar nerves, which had been cut distally, caused vesical contraction response.
3. The vesical contraction response induced by the unilateral centripetal electro-stimulation of each ventral ramus of the distally cut L_5.6.7 lumbar nerves was remained after the additional and individual or successive section of the nervous pathways, e. g., the transection of the spinal cord at the level of Th_10-11, cutting of the contralateral ventral rami of the L_5.6.7 lumbar nerves, bilateral cutting of the hypogastric nerve, bilateral L₇ ganglionectomy of the sympathetic trunk, and bilateral cutting of the pudendal nerve.
4. The vesical contraction response, whose appearance was confirmed in advance after cutting various nerves as described above, disappeared after the additional transection of the spinal cord at the level of L₇-S₁, or bilateral cutting of the pelvic nerve.
5. From the results obtained above, it was assumed that the lower half of the lumbar spinal cord of the dog posess a certain functional mechanism, which receives the centripetal stimuli via the ventral rami of the lower lumbar spinal nerves, mediates it to the efferent system in the sacral cord via some intraspinal descending systems, and makes the urinary bladder contract via the pelvic nerve.