Effects of dopamine on veins in humans: comparison with noradrenaline and influence of age.
OBJECTIVE
To compare the venoconstricting effect of dopamine with that of noradrenaline and to investigate the influence of age on the responsiveness to dopamine in human subjects.


METHODS
In eight young and eight elderly male subjects, increasing doses of dopamine or noradrenaline were infused into a dorsal hand vein and its diameter was measured using a linear variable differential transformer.


RESULTS
There was no significant difference between the maximum venoconstriction (Emax) for dopamine and that for noradrenaline. The infusion rate to induce 50% of Emax (ED50) for dopamine in the young and elderly subjects was 363 ng x min(-1) and 352 ng min(-1), and the ED50 for noradrenaline was 40.7 ng min(-1) and 43.8 ng x min(-1), respectively. Neither in the Emax nor in the ED50 for these drugs were there significant differences between the young and elderly subjects.


CONCLUSIONS
The venoconstricting effect of dopamine is 5-20 times less than that of noradrenaline, and aging does not influence the responsiveness to dopamine and noradrenaline in human subjects.
Harada
K
K
Department of Clinical Pharmacology, Jichi Medical School, Tochigi, Japan. kahikeko@jichi.ac.jp
Ohmori
M
M
Kito
Y
Y
Fujimura
A
A
D000328:Adult; D000367:Age Factors; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D018592:Cross-Over Studies; D004298:Dopamine / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000008:administration & dosage / Q000494:pharmacology; D013599:Systole; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000494:pharmacology; D014680:Veins / Q000187:drug effects* / Q000502:physiology
D014662:Vasoconstrictor Agents; D004298:Dopamine; D009638:Norepinephrine