Neural and extraneural catecholamine production by rat kidneys

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Abstract
Catecholamine production by innervated kidneys was examined by radioenzymatic assay of norepinephrine (NE), epinephrine (E), and dopamine (DA) in lymph, urine, arterial plasma, and renal venous plasma of hydropenic rats. Denervation reduced NE excretion in urine by 18% and both NE and DA efflux in renal venous plasma by 37 and 30%, respectively. The kidney's handling of E was unaltered by denervation. Renal nerves added 1.0 +/- 0.2 ng/min to the efflux of NE in urine and renal venous plasma. Denervation reduced this efflux to -0.1 +/- 0.2 ng/min. DA efflux from innervated kidneys was 1.4 +/- 0.2 ng/min but only half came from renal nerves, as denervated kidneys released 0.7 +/- 0.1 ng/min. Renal lymph from innervated kidneys contained slightly more NE but less DA than arterial plasma. We conclude that renal nerves release both NE and DA but that half of the renal contribution to urine and renal venous plasma DA efflux comes from extraneuronal tissue. Renal lymph NE and DA concentrations are similar to those in arterial plasma, suggesting that peritubular concentrations are low everywhere except within renal clefts.