Effect of neuropeptide Y on norepinephrine-induced constriction in the rabbit facial artery after carotid artery occlusion

Abstract

Background/Aim. Atherosclerotic-occlusive changes could be observed in orofacial branches of the external carotid artery. Atherosclerosis-induced ischemia caused alteration in production and release of endothelial factors. The aim of this study was to investigate the influence of carotid artery occlusion (10, 30 and 60 min) on vascular effects of norepinephrine (NOR) and neuropeptide Y (NPY) in the isolated glandular branch of the rabbit facial artery, the main feeding artery for the submandibular gland. Method. Changes in isometric tension were recorded in organ bath studies with arterial rings, before and after carotid artery occlusion. Results. Concentrationdependent vasocontractile effect of NOR was significantly augmented after 30 and 60 min of carotid occlusion, but only in the rings with intact endothelium. Given alone, NPY showed no effect in isolated glandular branch of the rabbit facial artery, but enhanced NOR vasoconstriction in all the investigated rings. NOR vasocontractile effect enhancement in the presence of NPY was attenuated after 30 and 60 min of carotid occlusion. Also, enhancement of NOR vasoconstriction by NPY was significantly higher in endothelium-intact rings compared to endotheliumdenuded rings obtained after 30 and 60 min of carotid occlusion. Conclusion. The present investigation provides results of increased vasocontractile effect of NOR and decreased enhancing effect of NPY on NOR vasoconstriction in the rabbit facial artery after carotid occlusion that is related to altered endothelium function.Uvod/Cilj. Pokazano je da se okluzivne promene ateroskleroticne prirode mogu opaziti na orofacijalnim granama spoljne karotidne arterije. Ishemija izazvana aterosklerozom, dovodi do poremecaja stvaranja i oslobadjanja faktora poreklom iz endotela. Cilj ovog istrazivanja bio je da se ispita uticaj okluzije karotidne arterije (10, 30 i 60 min) na vazokontraktilne efekte norepinefrina (NOR) i neuropeptida Y (NPY) na izolovanoj zlezdanoj grani facijalne arterije kunica, glavne dovodne arterije za submandibularnu zlezdu. Metode. U kupatilu za izolovane krvne sudove ispitivane su izometrijske promene tonusa arterijskih preparata, pre i posle okluzije karotidne arterije. Rezultati. Koncentracijski-zavisan vazokontraktilni efekat NOR bio je znacajno veci posle 30 i 60 min karotidne okluzije, ali samo na preparatima sa ocuvanim endotelom. Primenjen u rastucim koncentracijama, NPY nije imao efekta na tonus izolovane zlezdane grane facijalne aterije kunica, ali je povecao vazokontraktilni efekat NOR na svim ispitivanim preparatima. Povecanje vazokontraktilnog efekta NOR u prisustvu NPY bilo je znacajno manje posle 30 i 60 min okluzije. Takodje, efekat NPY posle karotidne okluzije bio je znacajno veci na preparatima sa ocuvanim endotelom u odnosu na preparate sa uklonjenim endotelom. Zakljucak. Ovo istrazivanje pokazalo je povecanje vazokontraktilnog efekta NOR i smanjenje potencirajuceg efekta NPY na vazokonstrikciju izazvanu NOR na facijalnoj arteriji kunica posle okluzije karotidne arterije koje su povezane sa promenjenom funkcijom endotela. PR Projekat Ministarstva nauke Republike Srbije, br. 175021