Ji. Sudo et al., HIGHER DOPAMINE LEVEL IN LYMPH FROM THE CERVICAL LYMPH TRUNK THAN IN PLASMA FOLLOWING INTRAVENOUS BOLUS INJECTION OF L-DOPA IN RATS, Biological & pharmaceutical bulletin, 18(4), 1995, pp. 610-614
To clarify the mechanism(s) responsible for nausea and vomiting induce
d by L-dopa administration, dopamine levels in the plasma and lymph of
rats were investigated in the 60-min period following an intravenous
bolus of L-dopa (2.5 mg/kg body weight). The dopamine level in plasma
from the femoral artery was the highest at 5 min immediately after the
L-dopa injection, and was eliminated thereafter. Shelving the same te
ndency as the plasma, the lymph from the thoracic duct showed a maxima
l increase of dopamine at 0 to 10 min, and a rapid decrease later. In
contrast, the dopamine level in the lymph from the cervical lymph trun
k increased, peaked at 10 to 20 min, and fell gradually thereafter. Th
e dopamine level in the cervical lymph was higher than that in the tho
racic lymph. When these data were kinetically analyzed, the cervical l
ymph had a larger area under the dopamine concentration-time curve tha
n the thoracic lymph. Both the cervical lymph and the thoracic lymph h
ad longer values of dopamine mean residence time than the plasma. Our
findings revealed that when L-dopa was administered with an intravenou
s bolus, dopamine was higher and remained longer in the cervical lymph
than in the rest of the body.