Lack of involvement of the kallikrein-kinin system in the depressor effect of alpha-methyldopa in normotensive rats.
1. We evaluated the involvement of circulating kinins in the hypotensive effect of the antihypertensive drug alpha-methyldopa (alpha-MD) in normotensive rats. 2. The alpha-MD effects were more pronounced in urethane-anesthetized rats than in unanesthetized animals. 3. Treatment with alpha-MD did not affect the circulating levels of kininogen, the bradykinin precursor. 4. Pretreatment with captopril that potentiates the depressor effects of bradykinin did not potentiate the hypotension to alpha-MD. 5. The lack of changes in kininogen levels and the failure of captopril to potentiate the depressor effects of alpha-MD rules out an involvement of the circulating kallikrein-kinin system in the response to alpha-MD.
Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Brazil.
F L
FL
Lebrun
I
I
Lebrun
F M
FM
Corrêa
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001920:Bradykinin / Q000494:pharmacology; D002216:Captopril / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D006168:Guinea Pigs; D007610:Kallikreins / Q000502:physiology*; D007704:Kininogens / Q000097:blood; D007705:Kinins / Q000502:physiology*; D008297:Male; D008750:Methyldopa / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D007704:Kininogens; D007705:Kinins; D008750:Methyldopa; D002216:Captopril; D007610:Kallikreins; D001920:Bradykinin