Potentiation by neuropeptide Y of 5HT2A receptor-mediated contraction in porcine coronary artery

Updated Role of Neuropeptide Y in Nicotine-Induced Endothelial Dysfunction and Atherosclerosis

Cardiovascular disease is the leading cause of death worldwide. Endothelial dysfunction of the arterial vasculature plays a pivotal role in cardiovascular pathogenesis. Nicotine-induced endothelial dysfunction substantially contributes to the development of arteriosclerotic cardiovascular disease. Nicotine promotes oxidative inflammation, thrombosis, pathological angiogenesis, and vasoconstriction, and induces insulin resistance. However, the exact mechanism through which nicotine induces endothelial dysfunction remains unclear. Neuropeptide Y (NPY) is widely distributed in the central nervous system and peripheral tissues, and it participates in the pathogenesis of atherosclerosis by regulating vasoconstriction, energy metabolism, local plaque inflammatory response, activation and aggregation of platelets, and stress and anxiety-related emotion. Nicotine can increase the expression of NPY, suggesting that NPY is involved in nicotine-induced endothelial dysfunction. Herein, we present an updated review of the possible mechanisms of nicotine-induced atherosclerosis, with a focus on endothelial cell dysfunction associated with nicotine and NPY.

Contribution of thromboxane a₂ in rat common carotid artery response to serotonin

Serotonin is a vasoactive substance that in different blood vessels mostly induces vasoconstriction. Considering the important role of common carotid artery in brain blood supply, the aims of this study were to investigate the effect of serotonin on isolated rat common carotid artery and also to examine participation of intact endothelium, cyclooxygenase products, Ca⁺⁺ channels and 5-HT₂ receptors in serotonin-evoked action. Endothelium was mechanically removed from some vascular rings. Circular artery segments were placed in organ baths containing Krebs–Ringer bicarbonate solution. Cumulative concentration-contraction curves for serotonin were obtained in rings previously equilibrated at basal tone. Serotonin produced concentration-dependent contraction, which was unaltered by endothelial denudation. Serotonin-induced effect was notably and comparably reduced by indomethacin (cyclooxygenase inhibitor) or OKY–046 (thromboxane A₂-synthase inhibitor) on intact or denuded rings. Nifedipine (Ca⁺⁺ channel blocker) or ketanserin (5-HT₂ receptor antagonist) strongly reduced serotonin-evoked effect. Our results suggest that serotonin produced concentration-dependent and endothelium-independent contraction of carotid artery, which was initiated by activation of 5-HT₂ receptors located on smooth muscle cells and mediated via L-type Ca⁺⁺ channels. Thromboxane A₂ from smooth muscle cells notably contributed to the overall contraction of carotid artery induced by serotonin.

Sarpogrelate protects against high glucose-induced endothelial dysfunction and oxidative stress

This study was designed to investigate the effect of sarpogrelate hydrochloride on impaired endothelium-dependent relaxation (EDR) induced by high glucose in isolated rat aorta. Both acetylcholine-induced EDR and sodium nitroprusside-induced endothelium-independent relaxation (EIR) were measured after the rings were exposed to high glucose in the absence and presence of sarpogrelate hydrochloride. Co-incubation of aortic rings with high glucose for 24h resulted in a significant inhibition of EDR, but had no effects on EIR. After incubation of the rings in the co-presence of sarpogrelate hydrochloride with high glucose for 24h, sarpogrelate hydrochloride significantly attenuated impaired EDR. This protective effect of sarpogrelate hydrochloride was abolished by N(G)-nitro-L-arginine methyl ester. Sarpogrelate hydrochloride significantly decreased superoxide anion (O(2)(-)) production and increased superoxide dismutase (SOD) activity and the nitric oxide (NO) release. These results suggest that sarpogrelate hydrochloride can restore impaired EDR induced by high glucose in isolated rat aorta, which may be related to scavenging oxygen free radicals and enhancing NO production.

Serotonin (5-HT) in veins: not all in vain

The circulatory system consists of veins and arteries. Compared with arteries, veins have been neglected in cardiovascular research. Although veins are significantly less muscular than similarly sized arteries, the contribution of veins to cardiovascular homeostasis cannot be left un-noted because veins accommodate 70% of the circulating blood. Circulating blood platelets contain the majority of systemic 5-HT (5-hydroxytryptamine; serotonin). Similar to venous function, the physiological role of 5-HT in the cardiovascular system is not well understood. Here, we present not only a review on 5-HT and veins but ways in which these two topics might intersect in a physiologically relevant manner. Here we show the novel findings that veins exhibit higher amounts of intracellular 5-HT than arteries. Moreover, we also show evidence that, similar to arteries, veins have the ability to uptake 5-HT. In this review, we introduce the venous system as a reservoir for 5-HT in the periphery, suggesting that veins, in addition to arteries, may represent an important target for drugs that interfere with the serotonergic system. In addition, the serotonergic system from synthesis to metabolism, 5-HT receptor activation and venous diseases will also be discussed.