Abstract 156: The Nitroxyl Donor Angeli's Salt Elicits Concomitant Concentration-Dependent Coronary Vasodilatory and Inotropic Actions in the Intact Rat Heart
Nitroxyl (HNO) is a novel redox sibling of NO• that elicits vasodilator, antihypertrophic and superoxide-suppressing actions. HNO is however resistant to scavenging by superoxide, and has high reactivity with thiols (enabling potent enhancement of LV function). In the present study, hearts from adult male Sprague-Dawley rats were Langendorff-perfused at constant pressure. Dose-response curves to the HNO donor Angeli’s salt were performed following preconstriction with U46619 to ∼50% of baseline coronary flow (CF). Angeli’s salt (10pmol-10µmol, n=6) elicited significant dose-dependent increases in left ventricular systolic pressure (LVSP), LV developed pressure (LVDP), LV end-diastolic pressure (LVEDP), LV±dP/dt, and CF. The effects of the highest dose of Angeli's salt studied on LV function are shown in the Table; these were significantly inhibited by co-administration of the HNO scavenger L-cysteine (4mM, n=6) or the soluble guanylyl cyclase inhibitor ODQ (10µM, n=5). The EC50 for Angeli's salt-induced vasodilatation was increased from -8.6±0.3mol to -7.5±0.2mol (p<0.01) and -7.6±0.3mol (p<0.05) by L-cysteine and ODQ, respectively. Although CGRP is a putative mediator of HNO actions, both the inotropic and vasodilator actions of Angeli's salt were insensitive to the CGRP antagonist CGRP8-37 (0.1µM, n=5). The vehicle for Angeli’s salt, 0.01M NaOH, had no effect on any of these parameters (n=3, results not shown). Our results demonstrate that the cardiac effects of Angeli’s salt are thiol-sensitive, and mediated by HNO and cGMP, but not CGRP. HNO donors represent potential therapy for the failing heart, alone or in addition to standard care.
- © 2012 by American Heart Association, Inc.