Behaviour of regional adrenergic outflow in mild-to-moderate renal failure.
OBJECTIVE
Chronic renal failure is characterized by a marked sympathetic activation. No information exists, however, as to whether the adrenergic overdrive is confined to selected vascular districts or is rather generalized to the whole cardiovascular system.


METHODS
In 15 patients aged 60.5 +/- 2.0 years (mean +/- SEM) with stable chronic renal failure belonging to stage 2-3 of the Kidney Foundation classification and in 12 age-matched healthy controls, we measured arterial blood pressure (Finapres), heart rate (ECG), venous plasma norepinephrine (high-performance liquid chromatography) and postganglionic sympathetic nerve traffic in skeletal muscle and skin areas (microneurography). Muscle and skin nerve traffic measurements were made in a randomized sequence over two periods of 30 min each, spaced by a 20-30-min interval. Measurements also included evaluation of skin sympathetic responses to emotional stimuli.


RESULTS
Muscle sympathetic nerve traffic was markedly and significantly greater in renal failure patients compared with controls (58.2 +/- 3.6 vs. 36.8 +/- 5.7 bursts/100 heart beats, P < 0.01), with this also being the case for plasma norepinephrine (380.6 +/- 63 vs. 210.8 +/- 29 pg/ml, P < 0.05). By contrast, skin sympathetic nerve traffic was superimposable in the two groups (11.5 +/- 0.8 vs. 12.7 +/- 1.7 bursts/minute, P = not significant), this being the case also for the responses to emotional arousal.


CONCLUSIONS
These data provide the first evidence that the sympathetic activation characterizing renal failure is not generalized to the entire cardiovascular system. This may depend on the fact that the two sympathetic districts are governed by mechanisms that are differently affected by the chronic uraemic state.
Grassi
Guido
G
Dipartimento di Medicina Clinica e Prevenzione, Università Milano-Bicocca, Clinica Medica, Ospedale San Gerardo, Monza, Italy. guido.grassi@unimib.it
Seravalle
Gino
G
Arenare
Francesca
F
Buccianti
Gherardo
G
Furiani
Silvia
S
Ilardo
Valeria
V
Bolla
Gianbattista
G
Mancia
Giuseppe
G