Functional Innervation of Rat Mesenteric Arteries Is Regulated by Thyroid Hormones

Abstract

Thyroid hormones (THs) have been shown to affect cardiovascular function, and we previously demonstrated the modulatory action of THs on the function of rat aorta through different endothelial factors. On the other hand, innervation regulates the function of mesenteric arteries, which contribute to the control of peripheral vascular resistance. In view of these data, the aim of this study was to investigate whether THs influence the function of adrenergic and nitrergic innervations. For this purpose, endothelium‐denuded mesenteric artery segments from control and thyroidectomized male Wistar rats (4 months‐old) were used to analyze: (i) the contractile response induced by electrical field stimulation (EFS); (ii) the effect of the alpha‐adrenergic receptor antagonist, phentolamine, or the nitric oxide (NO)‐synthase inhibitor, L‐NAME, on the EFS‐induced response; (iii) the vasomotor response induced by noradrenaline (NA) and by the NO donor, sodium nitroprusside (SNP); and (iv) the basal and EFS‐induced NO release. The results showed that hypothyroidism increased the EFS‐ and NA‐induced contraction, while it did not modify the reduced EFS‐induced response after phentolamine incubation. Regarding nitrergic innervation, hypothyroidism reduced the EFS‐induced NO release as well as its vasodilator action, and L‐NAME failed to modify the EFS‐induced contraction. These findings suggest a preventive role of THs on noradrenergic and nitrergic function of rat mesenteric artery.Support or Funding InformationSupportedby grants (to M.F.) from the Fondo de Investigaciones Sanitarias (PI1100406), Comunidadde Madrid (S2013/ABI‐2783, “INSPIRA1‐CM”) and Fondo Europeo de DesarrolloRegional.