title: Differential regulation of the nitric oxide-cGMP pathway exacerbates postischaemic heart injury in stroke-prone hypertensive rats.
abstract: Using a working perfused heart model, we investigated the hypothesis that alterations in the NO-cGMP pathway may exacerbate postischaemic mechanical dysfunction in the hypertrophied heart. Ischaemia for 25 min followed by reperfusion for 30 min produced marked cardiac mechanical dysfunction in both stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar Kyoto rats (WKY). Exogenous treatment with S-nitroso-N-acetyl-dl-penicillamine (SNAP), a NO donor, had beneficial effects on the cardiac dysfunction induced by ischaemia-reperfusion (I/R) in the WKY heart, but the cardioprotective effect of SNAP was eliminated by guanylyl cyclase inhibitor. Cardiac cGMP levels were increased by SNAP or ischaemia in WKY. In contrast, in SHRSP hearts, SNAP could not alleviate the cardiac dysfunction caused by I/R. Pre-ischaemia, the cardiac cGMP level was significantly higher in SHRSP than in WKY; however, no significant difference was found after SNAP and ischaemia. The myocardial Ca(2+)-dependent NO synthase (NOS) activity increased at the end of ischaemia in WKY. Conversely, the Ca(2+)-independent NOS activity and protein levels were upregulated by I/R in the SHRSP myocardium. In the SHRSP hearts, non-selective NOS and selective Ca(2+)-independent NOS inhibitors or antioxidant treatment alleviated cardiac dysfunction caused by I/R. Moreover, mRNA expression and Western blotting analysis of cGMP-dependent protein kinase type I showed more deterioration of SHRSP hearts compared with WKY. These results suggest that: (1) the NO-dependent cardioprotective effect is depressed; and (2) overproduction of NO derived from Ca(2+)-independent NOS contributes to postischaemic heart injury in the hypertrophied heart of hypertensive status.
authors.affiliation: Department of Drug Safety Evaluation, Developmental Research Laboratories, Shionogi & Co., Ltd, 3-1-1 Futaba-cho, Toyonaka, Osaka, 561-0825, Japan. tetsuji.itoh@shionogi.co.jp
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Itoh
authors.forename: Masao
authors.initials: M
authors.lastname: Haruna
authors.forename: Kohji
authors.initials: K
authors.lastname: Abe
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism; D006973:Hypertension / Q000150:complications; D017379:Hypertrophy, Left Ventricular / Q000209:etiology / Q000628:therapy*; D019157:Ischemic Preconditioning, Myocardial / Q000009:adverse effects*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D015428:Myocardial Reperfusion Injury / Q000209:etiology / Q000378:metabolism* / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D016277:Ventricular Function, Left / Q000187:drug effects; D017725:Ventricular Pressure / Q000187:drug effects
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D006152:Cyclic GMP; D002118:Calcium