Influence of Ageing on Vascular Reactivity and Receptor Expression in Rabbit Aorta: A Complement to Elastocalcinosis and Smooth Muscle Mechanisms
Received 26 October 2019
Accepted for publication 26 February 2020
Published 20 April 2020 Volume 2020:15 Pages 537—545
Checked for plagiarism Yes
Review by Single-blind
Peer reviewer comments 2
Editor who approved publication: Dr Richard Walker
Nelson Ivan Cupitra, Juan C Calderón, Raul Narvaez-Sanchez
Physiology and Biochemistry Research Group-PHYSIS, Faculty of Medicine, University of Antioquia, Medellin, Colombia
Correspondence: Raul Narvaez-Sanchez Carrera 51 D #62-29, Office 203, Medellin, Colombia
Tel +57 42196030
Aim: To contribute to the knowledge about the mechanisms involved in aortic stiffness due to ageing.
Materials and Methods: Aortic rings from young (1.5± 0.5 months, 0.8± 0.2 kg), adult (6± 0.5 months, 2.7± 0.5 kg) and old (28± 8 months, 3.2± 0.8 kg) male New Zealand rabbits were used to evaluate: 1) intima-media thickness by optical microscopy; 2) vascular reactivity (VR) in terms of sensitivity (pD2) and efficacy (Emax) to KCl; phenylephrine (PE); U-46619, a thromboxane A2 receptor agonist, TXA2; carbachol (CCh), isoproterenol and sodium nitroprusside (SNP), using organ bath experiments; and 3) the expression of receptors α 1, β 2 and thromboxane-prostanoids (TP), by immunofluorescence.
Results: Ageing 1) did not change the thickness of tunica; 2) significantly reduced the pD2 to KCl, increased the pD2 to PE and reduced both the pD2 and Emax to TXA2, CCh and isoproterenol, and reduced the pD2 to SNP; and 3) significantly increased the expression of α 1 and β 2 receptors in the intima and adventitia, and the expression of TP only in the adventitia.
Conclusion: Our results suggest that ageing makes the aorta more reactive to α 1 adrenergic contraction, and it could be a compensation for lower responsiveness to prostanoids. The aged aorta is less reactive to endothelium-dependent and non-dependent relaxation, and the vessel seems to try to compensate for that stiffness increasing β 2 receptors, although probably less functional. These results complement the proposed mechanisms of elastocalcinosis and smooth muscle rigidity, expanding the vision that should guide the treatment of aortic stiffness due to aging.
Keywords: ageing, aortic rings, vascular reactivity, vascular smooth muscle, vascular stiffness
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