Extracellular Uridine Nucleotides-Induced Contractions Were Increased in Femoral Arteries of Spontaneously Hypertensive Rats

<b><i>Introduction:</i></b> Femoral arterial dysfunction including abnormal vascular responsiveness to endogenous ligands was often seen in arterial hypertension. Extracellular nucleotides including uridine 5′-diphosphate (UDP) and uridine 5′-triphosphate (UTP) play important roles for homeostasis in the vascular system including controlling the vascular tone. However, responsiveness to UDP and UTP in femoral arteries under arterial hypertension remains unclear. The aim of this study was to investigate if hypertension has an effect of vasoconstrictive responsiveness to UDP and UTP in femoral arteries of spontaneously hypertensive rats (SHRs) and Wistar-Kyoto rats (WKYs) after 7 and 12 months old. <b><i>Methods:</i></b> Organ baths were conducted to determine vascular reactivity in isolated femoral arterial rings. <b><i>Results:</i></b> In femoral arteries obtained from 12-month-old rats, augmented contractile responses to UDP and UTP were seen in femoral arteries of SHR than in those of WKY under situations not only intact but also nitric oxide synthase inhibition, whereas no difference of extracellular potassium-induced vasocontraction was seen in both SHR and WKY groups. Similar contraction trends occurred in femoral arteries obtained from 7-month-old rats. Moreover, contractions induced by UDP and UTP were increased in endothelium-denuded arteries. Cyclooxygenase inhibition decreased the contractions induced by these nucleotides and abolished the differences in responses between the SHR and WKY groups. <b><i>Conclusions:</i></b> This study demonstrates the importance of regulation of extracellular uridine nucleotides-induced contractions in hypertension-associated peripheral arterial diseases.