Age-related differences in the β-adrenergic vasodilator response in rat aortic rings

Maria Del Carmen Castillo-Hernandez, Noemi Meraz-Cruz, Gustavo Guevara-Balcazar, Jorge Lopez-Canales, Oscar Lopez-Canales, Norma Galindo, Carlos Castillo-Henkel

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Abstract

Mechanisms underlying age-dependent changes in vasodilator responses to β-adrenergic drugs are poorly understood. The aim of the current study was to compare responses to isoproterenol (a non-selective β-adrenergic receptor agonist) in phenylephrine or KCl precontracted aortic rings from 3 week and 3 month old male Wistar rats. Both the mechanism and the subtype of β-adrenergic receptor underlying the response to isoproterenol in the both age groups were examined. Endothelial removal, pre-contraction with KCl (40 mM), pre-treatment with tetraethylammonium or with Nω-Nitro-L-arginine methyl ester inhibited the vasodilator response to isoproterenol only in aortic rings from older rats. The inhibition was total when TEA and L-NAME were administered together. In both age groups the response to isoproterenol was unaffected by the β 1-adrenergic antagonist CGP20712A, but was significantly inhibited by ICI 118551 (a β 2- adrenergic-antagonist) and to a greater extent by SR 59230A (a non-selective β 3-adrenergic antagonist), the inhibition being more evident in the older rats. Unlike younger rats, in older animals the response to isoproterenol was partially dependent on endothelial nitric oxide and on K + channels. In both age groups, β 2- and β 3-, but not β 1- adrenergic receptors were involved. The degree of relative participation of β 2 and β 3 adrenergic receptors may change with age and explain the differences in response to isoproterenol.

Original languageEnglish
Pages (from-to)29-32
Number of pages4
JournalProceedings of the Western Pharmacology Society
Volume53
StatePublished - 2010

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