On the role of alpha-methyldopamine in the antihypertensive effect of alpha-methyldopa.
In renal hypertensive rats the cerebral concentration of alpha-methyldopa, alpha-methyldopamine, alpha-methylnoradrenaline, dopamine and noradrenaline as well as the blood-pressure were determined simultaneously. The antihypertensive effect followed a time course identical to that of the increase in the cerebral concentration of alpha-methyldopamine and of the decrease in the concentration of dopamine, whereas lowering of blood pressure on the one hand, and changes in the levels of alpha-methylnoradrenaline and noradrenaline, on the other, were not related to each other. Dose-response relationships showed the same correlations and lack of correlations, respectively. These results suggest that non-betat-hydroxylated catecholamines play a major role in mediating the antihypertensive effect of alpha-methyldopa or, alternatively, that only the newly biosynthesized alpha-methyl-noradrenaline is effective in lowering blood pressure.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001923:Brain Chemistry / Q000187:drug effects*; D003846:Deoxyepinephrine / Q000032:analysis / Q000502:physiology*; D004298:Dopamine / Q000031:analogs & derivatives* / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D006977:Hypertension, Renal / Q000503:physiopathology; D008297:Male; D008750:Methyldopa / Q000032:analysis / Q000494:pharmacology*; D009638:Norepinephrine / Q000032:analysis; D051381:Rats; D009435:Synaptic Transmission / Q000187:drug effects; D013997:Time Factors
D008750:Methyldopa; D003846:Deoxyepinephrine; D004298:Dopamine; D009638:Norepinephrine