Selective destruction of renal afferent versus efferent nerves in rats

Previous anatomic studies demonstrated that afferent projections from the left kidney of the rat passed predominantly through the dorsal roots of spinal segments T10-L1. Selective destruction of renal afferent nerves, without damaging renal efferent nerves, was attempted by severing the dorsal roots carrying the afferent fibers. In anesthetized rats, the dorsal left side of the spinal cord was exposed through a partial laminectomy at vertebral sections T10-L1; and the dorsal roots were carefully isolated and cut. Four to ten days after surgery, arterial pressure and hindquarter vascular resistance were maximally reduced by 14 +/- 2 mmHg and 42 +/- 1%, respectively, during electrical stimulation of renal afferent fibers in sham-operated rats. In rats with selective dorsal rhizotomy no significant changes in arterial pressure or hindquarter vascular resistance were observed after renal afferent nerve stimulation. Renal vasoconstrictor responses to electrical stimulation of the left greater splanchnic nerve or posterior hypothalamic area were not different between sham and rhizotomized rats. These data demonstrate that severing dorsal roots T10-L1 cause a functional afferent denervation of the kidney, without impairing renal efferent nerve function.