We studied the effect of unilateral sympathectomy on rat quadriceps and
gastrocnemius muscle concentrations of endogenous dihydroxyphenylalanine
(DOPA), dopamine (DA), and norepinephrine (NE) and assessed the
relationships between these catecholamines in several rat tissues.
Catecholamines were measured by reverse-phase high-performance liquid
chromatography with electrochemical detection. Sympathectomy decreased NE
and DA concentrations of muscles to approximately 10% of control values,
whereas the DOPA concentration tended to increase. Relatively high
concentrations of DOPA were found in the gastrointestinal tract, kidney,
and spleen. No correlations were obtained between the tissue concentration
of DOPA and NE. A DA-to-NE ratio approximately 1% was observed in liver,
muscle, pancreas, spleen, and heart, whereas we found exponentially
increasing DA values with increasing NE concentration in tissues obtained
from stomach, small and large intestine, kidney, and lung. In conclusion,
endogenous DOPA in muscle tissue is not located in sympathetic nerve
terminals but probably in muscle cells. DA concentrations in the
gastrointestinal tract and in the kidneys were greater than could be
ascribed to its role as a precursor in the biosynthesis of NE.
E. Eldrup, E. A. Richter and N. J. Christensen
Department of Internal Medicine and Endocrinology, Herlev University Hospital, Denmark.
Am J Physiol Endocrinol Metab 256: E284-E287, 1989;