Enhanced inhibition by melatonin of alpha-adrenoceptor-induced aortic contraction and inositol phosphate production in vascular smooth muscle cells from spontaneously hypertensive rats
Abstract
To test the hypothesis that the enhanced inhibition by melatonin of the norepinephrine-induced vasoconstriction and formation of inositol phosphate in spontaneously hypertensive rats are mediated by its antioxidant effect Aortic rings from spontaneously hypertensive rats and age-matched Wistar-Kyoto rats were used for measuring vascular contraction forces. Cultured aortic smooth muscle cells were prelabelled with myo-[2-3H]-inositol for evaluation of formation of inositol phosphate after exposure to agonist or antagonist Basal or forskolin-induced formation of cyclic AMP was evaluated using a [3H]-cyclic AMP assay system. Oxygen-derived free radicals were generated with a hypoxanthine and xanthine oxidase system. The inhibition of the norepinephrine-induced aortic contraction by melatonin was more potent in spontaneously hypertensive than it was in Wistar-Kyoto rats. The inhibition of the norepinephrine-induced formation of inositol phosphate by 0.3-300 micromol/l melatonin was also greater in smooth muscle cells from spontaneously hypertensive rats than it was in those cells from Wistar-Kyoto rats. In contrast, the inhibition of the norepinephrine-induced formation of inositol phosphate in smooth muscle cells from spontaneousl...Continue Reading
References
Increased inositol monophosphate production in cardiovascular tissues of DOCA-salt hypertensive rats
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