title: Chronic activation of endogenous angiotensin-converting enzyme 2 protects diabetic rats from cardiovascular autonomic dysfunction.
abstract: In this study, we evaluated whether the activation of endogenous angiotensin-converting enzyme 2 (ACE2) would improve the cardiovascular autonomic dysfunction of diabetic rats. Ten days after induction of type 1 diabetes (streptozotocin, 50 mg kg(-1) i.v.), the rats were treated orally with 1-[(2-dimethylamino)ethylamino]-4-(hydroxymethyl)-7-[(4-methylphenyl) sulfonyl oxy]-9H-xanthene-9-one (XNT), a newly discovered ACE2 activator (1 mg kg(-1) day(-1)), or saline (equivalent volume) for 30 days. Autonomic cardiovascular parameters were evaluated in conscious animals, and an isolated heart preparation was used to analyse cardiac function. Diabetes induced a significant decrease in the baroreflex bradycardia sensitivity, as well as in the chemoreflex chronotropic response and parasympathetic tone. The XNT treatment improved these parameters by ≈ 76% [0.82 ± 0.09 versus 1.44 ± 0.17 Ratio between changes in pulse interval and changes in mean arterial pressure (ΔPI/ΔmmHg)], ∼85% (-57 ± 9 versus -105 ± 10 beats min(-1)) and ≈ 205% (22 ± 2 versus 66 ± 12 beats min(-1)), respectively. Also, XNT administration enhanced the bradycardia induced by the chemoreflex activation by v 74% in non-diabetic animals (-98 ± 16 versus -170 ± 9 Δbeats min(-1)). No significant changes were observed in the mean arterial pressure, baroreflex tachycardia sensitivity, chemoreflex pressor response and sympathetic tone among any of the groups. Furthermore, chronic XNT treatment ameliorated the cardiac function of diabetic animals. However, the coronary vasoconstriction observed in diabetic rats was unchanged by ACE2 activation. These findings indicate that XNT protects against the autonomic and cardiac dysfunction induced by diabetes. Thus, our results provide evidence for the viability and effectiveness of oral administration of an ACE2 activator for the treatment of the cardiovascular autonomic dysfunction caused by diabetes.
authors.affiliation: Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
authors.forename: Tatiane M
authors.initials: TM
authors.lastname: Murça
authors.forename: Tatiane C S
authors.initials: TC
authors.lastname: Almeida
authors.forename: Mohan K
authors.initials: MK
authors.lastname: Raizada
authors.forename: Anderson J
authors.initials: AJ
authors.lastname: Ferreira
mesh_terms: D000085962:Angiotensin-Converting Enzyme 2; D000818:Animals; D001342:Autonomic Nervous System Diseases / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001919:Bradycardia / Q000188:drug therapy / Q000503:physiopathology; D002318:Cardiovascular Diseases / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000502:physiology; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D006943:Hyperglycemia / Q000188:drug therapy / Q000503:physiopathology; D008297:Male; D010275:Parasympathetic Nervous System / Q000187:drug effects* / Q000503:physiopathology*; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000503:physiopathology*; D013610:Tachycardia / Q000188:drug therapy / Q000503:physiopathology; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D014662:Vasoconstrictor Agents; D007703:Peptidyl-Dipeptidase A; C000705329:Ace2 protein, rat; D000085962:Angiotensin-Converting Enzyme 2