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Mechanisms of noradrenaline‐induced vasorelaxation in isolated femoral arteries of the neonatal rat
Author(s) -
Nishina H,
Ozaki T,
Hanson M A,
Poston L
Publication year - 1999
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0702641
Subject(s) - femoral artery , medicine , norepinephrine , cardiology , anesthesia , dopamine
Isolated arteries from the femoral circulation of Wistar rats mounted on a small vessel myograph demonstrated age related tension development to noradrenaline (NA, 1×10 −8 –5×10 −5 M ) day 20 greater than day 10 ( P < 0.005); day 100 greater than day 20 ( P < 0.001) and depolarizing potassium (125 m M ) buffer day 20 greater than day 10 ( P < 0.001). NA evoked dilatation in femoral arteries from neonatal rats (10 days) when added to unstimulated vessels or to those preconstricted with the thromboxane mimetic, U46619. Relaxation to NA was inhibited by L ‐NAME (0.1 m M ) ( P < 0.001), endothelial removal ( P < 0.001) and the α 2 ‐adrenoceptor antagonist, yohimbine (0.1 μ M ) ( P < 0.001). α 1 ‐ or β‐adrenoceptor antagonism was without effect. Relaxation was evoked in femoral arteries of the 10‐day‐old rats by the α 2 ‐adrenoceptor agonist UK14304 (1×10 −8 –5×10 −5 M ). This relaxation was also abolished by L ‐NAME (0.1 m M ) ( P < 0.001) or endothelial removal ( P < 0.001). α 2 ‐adrenoceptor‐mediated vasorelaxation was the predominant response to NA stimulation in femoral arteries of the neonatal rat. These responses were endothelium‐dependent and were NO‐mediated. British Journal of Pharmacology (1999) 127 , 809–812; doi: 10.1038/sj.bjp.0702641