Contribution of vascular tissue to the antiplatelet activity of sodium nitroprusside

Cigarette Smoking Is Related to Endothelial Dysfunction of Resistance, but Not Conduit Arteries in the General Population-Results From the Gutenberg Health Study

Aims: Cigarette smoking is one of the most complex and least understood cardiovascular risk factors. Importantly, differences in the tobacco-related pathophysiology of endothelial dysfunction, an early event in atherogenesis, between circulatory beds remain elusive. Therefore, this study evaluated how smoking impacts endothelial function of conduit and resistance arteries in a large population-based cohort.

Methods and results: 15,010 participants (aged 35–74 years) of the Gutenberg Health Study were examined at baseline from 2007 to 2012. Smoking status, pack-years of smoking, and years since quitting smoking were assessed by a computer-assisted interview. Endothelial function of conduit and resistance arteries was determined by flow-mediated dilation (FMD) of the brachial artery, reactive hyperemia index (RHI) using peripheral arterial tonometry, as well as by reflection index (RI) derived from digital photoplethysmography, respectively. Among all subjects, 45.8% had never smoked, 34.7% were former smokers, and 19.4% were current smokers. Mean cumulative smoking exposure was 22.1 ± 18.1 pack-years in current smokers and mean years since quitting was 18.9 ± 12.7 in former smokers. In multivariable linear regression models adjusted for typical confounders, smoking status, pack-years of smoking, and years since quitting smoking were independently associated with RHI and RI, while no association was found for FMD. Overall, no clear dose-dependent associations were observed between variables, whereby higher exposure tended to be associated with pronounced resistance artery endothelial dysfunction.

Conclusions: Cigarette smoking is associated with altered endothelial function of resistance, but not conduit arteries. The present results suggest that smoking-induced endothelial dysfunction in different circulatory beds may exhibit a differential picture.

Nitric oxide-releasing molecules at the interface of inorganic chemistry and biology: a concise overview

The useful aspects of nitric oxide (NO) are nowadays widely known. Due to the need for this molecule in the maintenance of homeostasis, NO-releasing compounds are tested every year to optimize its levels in a patient suffering from low NO production. This manuscript is an update of some important historical concerns about nitrosyl complexes having the ability to act as NO-releasing compounds under the influence of different chemically modified environments. At present, the search for efficient and less harmful NO-releasing molecules at desirable targets and concentrations has gained considerable momentum in nitrosyl chemistry. Iron, ruthenium, and manganese nitrosyls have been investigated elitely to disentangle their electronic transition (excitation) under visible light to act as NO donors without harming the healthy cells of a target. There is much evidence supporting the increase of NO lability if amino acids are used as complexing ligands, the design of a reduction center close to an NO grouping, and the development of porphyrin system-based nitrosyl complexes. From the overall survey, it may be concluded that the desirable properties of such scaffolds need to be evaluated further to complement the biological milieu.

CGRP-mediated cardiovascular effect of nitroglycerin

Organic nitrates, including nitroglycerin, produce vascular relaxation by releasing nitric oxide in vascular tissues near the plasma member of smooth muscle cells of veins and arteries. Calcitonin gene-related peptide (CGRP), a major transmitter in capsaicin-sensitive sensory nerves, is widely distributed in cardiovascular tissues and the release of CGRP is regulated by multiple autacoids including nitric oxide (NO). CGRP exerts complex cardiovascular effects including potent vasorelaxation and protective effects on myocytes and endothelial cells. Nitroglycerin activates sensory nerves fibres to release CGRP by generating NO and increasing cGMP level, and that the cardiovascular effects of nitroglycerin are partly mediated by endogenous CGRP.

eNOS-dependent vascular interaction between nitric oxide and calcitonin gene-related peptide in mice: gender selectivity and effects on blood aggregation

The present study was performed to explore a possible vascular interplay between nitric oxide (NO) and calcitonin gene-related peptide (CGRP). We examined factors affecting CGRP release by the NO donor, nitroglycerin (NTG) and the potential involvement of endothelial NO synthase (eNOS) using eNOS knockout (-/-) vs. wild-type (+/+) mice. In the female eNOS (+/+) mice, but not in males, in vitro NTG (0.73 mM) induced significant increases in the release of CGRP-like immunoreactivity (CGRP-LI) from the aorta and the heart but not from the small intestine. In eNOS (-/-) mice, NTG incubation did not induce any CGRP-LI changes in either gender. These results suggest that NTG-induced CGRP release is eNOS-dependent and tissue- and gender-selective. The functional implication of this NO-CGRP interaction was further examined by testing the anti-aggregatory action of acetylcholine (Ach). Ach-induced platelet inhibition was significantly enhanced by the addition of aorta segments of either gender. However, the female aorta segments exhibited a greater platelet inhibitory effect, which could be reversed by the blockade of either CGRP or eNOS. Our study revealed a novel eNOS-dependent interaction between NO and CGRP, and the possible participation of regulatory peptides in affecting platelet function and possibly cardiovascular protection in females.

Calcitonin gene-related peptide-dependent vascular relaxation of rat aorta. An additional mechanism for nitroglycerin

We investigated the involvement of calcitonin gene-related peptide (CGRP) in the vasodilatory mechanism of action of nitric oxide (NO) donors. The functional role of CGRP in NO donor-induced vasodilation of isolated rat aortic rings was determined by incubating these drugs with and without CGRP(8-37), a selective CGRP receptor antagonist. CGRP(8-37) (0.63 microM) induced rightward shifts in the vasodilatory concentration-response curves for nitroglycerin (NTG), Piloty's acid (PA), and SIN-1 (linsidomine). The EC(50) values for NTG, PA, and SIN-1 were increased by 8.3-, 5.2-, and 2.3-fold, respectively (P < 0.05). The release of CGRP from rat aorta in response to NTG and PA was measured specifically by radioimmunoassay. Thirty-minute incubations of NTG or PA with rat aorta induced 189.5 and 214.6% increases, respectively, in CGRP release when compared with the control (P < 0.05). The concentration-response curves of sodium nitroprusside (SNP), S-nitroso-acetylpenicillamine (SNAP), tetranitromethane (TNM), diethylamine NO complex (DEA-NO), and diethylenetriamine/nitric oxide adduct (DETA NONOate) were not inhibited significantly by CGRP(8-37) co-incubation (P 0.05). NO donors also were incubated with aortic strips, and NTG and PA alone induced significant formation of hydroxylamine, a NO(-) metabolite (232.4 and 364.9%, respectively, P < 0.05). These results indicate that only NTG and PA, and to a lesser extent SIN-1, stimulate the release of CGRP from the rat aorta, which subsequently contributes to the vasodilatory activity of these agents. The hydroxylamine formation suggests a possible link between NO(-) generation and CGRP release from the vascular wall.