HNO/cGMP-dependent antihypertrophic actions of isopropylamine-NONOate in neonatal rat cardiomyocytes: potential therapeutic advantages of HNO over NO˙

Abstract

RH. HNO/cGMP-dependent antihypertrophic actions of isopropylamine-NONOate in neonatal rat cardiomyocytes: potential therapeutic advantages of HNO over NO˙. Am J Physiol Heart Circ Physiol 305: H365-H377, 2013. First published May 31, 2013 doi:10.1152/ajpheart.00495.2012 is a redox congener of NO˙. We now directly compare the antihypertrophic efficacy of HNO and NO˙donors in neonatal rat cardiomyocytes and compare their contributing mechanisms of actions in this setting. Isopropylamine-NONOate (IPA-NO) elicited concentrationdependent inhibition of endothelin-1 (ET1)-induced increases in cardiomyocyte size, with similar suppression of hypertrophic genes. Antihypertrophic IPA-NO actions were significantly attenuated by L-cysteine (HNO scavenger), Rp-8-pCTP-cGMPS (cGMP-dependent protein kinase inhibitor), and 1-H-(1,2,4)-oxodiazolo-quinxaline-1-one [ODQ; to target soluble guanylyl cyclase (sGC)] but were unaffected by carboxy-PTIO (NO˙scavenger) or CGRP8-37 (calcitonin gene-related peptide antagonist). Furthermore, IPA-NO significantly increased cardiomyocyte cGMP 3.5-fold (an L-cysteine-sensitive effect) and stimulated sGC activity threefold, without detectable NO˙release. IPA-NO also suppressed ET1-induced cardiomyocyte superoxide generation. The pure NO˙donor diethylamine-NONOate (DEA-NO) reproduced these IPA-NO actions but was sensitive to carboxy-PTIO rather than L-cysteine. Although IPA-NO stimulation of purified sGC was preserved under pyrogallol oxidant stress (in direct contrast to DEA-NO), cardiomyocyte sGC activity after either donor was attenuated by this stress. Excitingly IPA-NO also exhibited acute antihypertrophic actions in response to pressure overload in the intact heart. Together these data strongly suggest that IPA-NO protection against cardiomyocyte hypertrophy is independent of both NO˙and CGRP but rather utilizes novel HNO activation of cGMP signaling. Thus HNO acutely limits hypertrophy independently of NO˙, even under conditions of elevated superoxide. Development of longer-acting HNO donors may thus represent an attractive new strategy for the treatment of cardiac hypertrophy, as stand-alone and/or add-on therapy to standard care. cardiac hypertrophy; cGMP-dependent protein kinase; nitric oxide; nitroxyl; superoxide CURRENT PHARMACOTHERAPY FOR heart failure tends to delay, but not reverse, cardiac hypertrophy. We have previously shown that NOṡ ignaling is an important antihypertrophic mechanism in the heart (44). NO˙is, however, yet to be realized as a pharmacotherapy for cardiac hypertrophy, largely a consequence of limitations at the level of myocardial asymmetric dimethylarginine (ADMA) and NO synthase (NOS; Ref. 57). HNO, a redox sibling of NO˙, is a novel regulator of cardiovascular function (26,38). NO˙and HNO share several common cardiac and vascular protective actions, ranging from potent vasodilator (2, 10, 12-14, 22, 23, 59) and antiplatelet actions (3, 4) to, more recently, antihypertrophic actions in cardiomyocytes (31). These actions are all mediated predominantly via sGC (10...

Chronic Administration of the Nitroxyl Donor 1-Nitrosocyclo Hexyl Acetate Limits Left Ventricular Diastolic Dysfunction in a Mouse Model of Diabetes Mellitus In Vivo

“…22,23,28 We have previously shown that Angeli salt and IPA-NO suppress cardiomyocyte ROS production in response to hypertrophic stimuli in cultured cardiomyocytes. 18,19 In the current study, the ability of diabetes mellitus to stimulate NADPHdriven LV superoxide generation (on lucigenin-enhanced chemiluminescence, confirmed on PEG-SOD-sensitive dihydroethidium fluorescence) was absent in 1-NCAtreated mice. This trend was reproduced on LV mitochondrial uncoupling protein 3 expression.…”

“…In the current study, all markers of diabetes mellitus-induced cardiomyocyte hypertrophy were attenuated by 1-NCA, consistent with previous short-term findings with classical HNO donors in isolated cardiomyocytes. 18,19 To our knowledge, this is the first evidence to demonstrate antihypertrophic actions of HNO in a chronic setting in vivo. The clear, diabetes mellitus-induced cardiomyocyte hypertrophy was accompanied by a trend for increased profibrotic connective tissue growth factor expression, which was absent in 1-NCA-treated diabetic mice.…”

“…9,12 Moreover, HNO enhances LV systolic and diastolic function, which persists in the failing heart and is independent, at least in part, from soluble guanylyl cyclase (sGC)-mediated vasodilator actions. 8,11,[13][14][15][16][17] Moreover, HNO exhibits antihypertrophic and superoxide-suppressing actions in the myocardium, 18,19 but these have yet to be extended to an in vivo setting. HNO donors may thus offer favorable actions in a range of cardiac pathologies.…”

“…Although sGC (in its reduced, Fe 2+ -containing form) is regarded as the receptor for NO•, 5,6 , HNO is an equipotent sGC stimulator. 19 HNO suppression of cardiomyocyte ROS production is mediated via sGC-dependent downregulation of NADPH oxidase. 18,19 Insufficient mouse LV tissue precluded determination of LV cGMP content here.…”

“…19 HNO suppression of cardiomyocyte ROS production is mediated via sGC-dependent downregulation of NADPH oxidase. 18,19 Insufficient mouse LV tissue precluded determination of LV cGMP content here. Unlike NO•, HNO is resistant to ROS scavenging, does not develop tolerance to its actions, and may target oxidized sGC.…”