HYPERTENSIVE EFFECT OF L-DOPA AND RELATED COMPOUNDS IN THE RAT

Publisher Website
Google Scholar
Abstract
The amino acid dihydroxyphenyl-alanine ("dopa"), given intraperiton. or intraven. in a dose of 12 mg./kg., causes a marked and sustained rise of the blood pressure of the rat. Similar rises are observed after hypophysectomy, or in renally hypertensive rats. Adrenalec-tomy abolishes the response initially, but not after the animals are maintained for 2 wks. with desoxycorticosterone. Bilateral nephrectomy enhances the magnitude and duration of the response. L-dopa differs in action from its corresponding amine (hydroxytyramine) both in vivo and in vitro. It could not be shown conclusively whether l-dopa exerts its pressor action by decarboxylation to a related amine, or by virtue of its reducing properties, or as a competing substrate for those enzymes which destroy epineph-rine. Catechol and acetaldehyde produce similar pressor responses in comparable doses, while chloracetocatechol results in mixed responses. The natural l-dopa is twice as active as dl-dopa. The blood pressure response of rats to l-dopa cannot be used as a measure of the decarboxylase content of the tissues, nor as an indicator of intrarenal O2 tension. Unless it can be shown that dopa has an entirely different mechanism of pressor action in man, it cannot be assumed that clinical responses to its intraven. injn. bear any relationship to the functional state of the kidneys.

This publication has 4 references indexed in Scilit: