Effects of chronic and acute aminoguanidine treatment on tail artery vasomotion in ageing rats

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Abstract
This study was designed to evaluate the effects of aminoguanidine, a selective inhibitor of the inducible isoform of nitric oxide synthase (iNOS), on the reactivity and intracellular calcium ([Ca2+]i) mobilization induced by noradrenaline in the perfused tail artery from aged WAG/Rij rats. Global mean internal diameter was 350±15 microns and wall thickness 161±3 microns. The influence of the endothelium on these responses was also analysed. The intracellular dye fura‐2 for [Ca2+]i measurements was used. Noradrenaline‐induced vasoconstriction decreased progressively from 3 to 20 and 30 months. Removal of the endothelium attenuated vasoconstriction in 20 and 30 month‐old rats (P−1 day−1, p.o.) to WAG/Rij rats from 20 to 30 months enhanced (P2+]i‐sensitivity of noradrenaline‐induced vasoconstriction. Aminoguanidine (300 μM) in vitro significantly shifted the concentration‐vasoconstriction curve to noradrenaline to the left (PPBritish Journal of Pharmacology (2000) 131, 1227–1235; doi:10.1038/sj.bjp.0703696