AJP - Renal Physiology, Vol 252, Issue 2 240-F245, Copyright © 1987 by American Physiological Society
Increased release of norepinephrine and dopamine from canine kidney during bilateral carotid occlusion
T. Bradley, P. Hjemdahl and G. F. DiBona
The renal overflow of norepinephrine (NE) and dopamine (DA) to plasma from
the innervated kidney was studied at rest and during sympathetic nervous
system activation by bilateral carotid artery occlusion (BCO) in
vagotomized dogs under barbiturate or barbiturate/nitrous oxide anesthesia.
BCO elevated arterial pressure and the arterial plasma concentrations of
NE, DA, and epinephrine (Epi). Renal vascular resistance (renal arterial
pressure kept constant) increased by 15 +/- 7% (P less than 0.05) and the
net renal venous outflows (renal venoarterial concentration difference X
renal plasma flow) of NE and DA were enhanced (P less than 0.05). To obtain
more correct estimates of the renal contribution to the renal venous
catecholamine outflow, we corrected for the renal extraction of arterial
catecholamines, assessed as the extractions of [3H]NE, [3H]DA, or
endogenous Epi. The [3H]NE corrected renal NE overflow to plasma increased
from 144 +/- 40 to 243 +/- 64 pmol X min-1 (P less than 0.05) during BCO,
which, when compared with a previous study of the [3H]NE corrected renal NE
overflow to plasma evoked by electrical renal nerve stimulation,
"corresponds" to a 40% increase in nerve impulse frequency from
approximately 0.6 Hz. If the renal catecholamine extraction was not taken
into account the effect of BCO was underestimated. The renal DA overflow to
plasma was about one-fifth of the NE overflow both at rest and during BCO,
indicating that there was no preferential activation of noradrenergic or
putative dopaminergic nerves by BCO.
