gms | German Medical Science

Peptidergic sensory nerve fibers from the dorsal root ganglia (DRG) provide afferent input to the central nervous system and could also contribute to the regulation of peripheral vascular system opposing the vasoconstrictor effects of the sympathetic nervous system by releasing vasodilatory peptides locally. Axons of DRG neurons of the lower thoracic cord project to resistance vessels in the lower limbs,. We tested the hypothesis, that peptidergic sensory neurons of the DRG in the lower thoracic cord show an altered sensitivity to mechanical stimuli in rat models of secondary hypertension.

Neurones from DRG (Th11 to L1) of rats with two secondary models of hypertension (2 kidney-1 clip hypertensive, 5/6 nephrectomized rats, respective controls) were cultured on coverslips for 2 days.. Whole cell patch recordings were obtained from the cells and current-time relationships established. Cells of all groups were characterised under control conditions and after exposure to hypoosmotic mannitol solution for 5 minutes to induce mechanical stress. Neurons of the same DRG with projections to the kidney were studied for comparison. Different cell populations were distinguished with a specific dye.

Hypoosmotic extracellular medium induced a significant change in conductance of the cells in all groups of rats. In hypertensive rats, responses of cells with non-renal axons were significantly different from normotensive controls: (2 kidney-1 clip hypertensives: delta -351„b52 pA *; 5/6 nephrectomized rats: delta -372„b43 pA * vers pooled normotensives: delta -190„b25 pA ; * p<0,05 vers. control).

Neurons from DRG in the lower thoracic cord with projections to the lower limbs exhibited an increased sensitivity to mechanical stress. We speculate that this observation may indicate an increased activity of these neurons, their axons and neurotransmitters in the control of resistance vessels in secondary hypertension.