ACE gene dosage determines additional autonomic dysfunction and increases renal angiotensin II levels in diabetic mice.

OBJECTIVES: The present study aimed to investigate cardiovascular autonomic modulation and angiotensin II (Ang II) activity in diabetic mice that were genetically engineered to harbor two or three copies of the angiotensin-converting enzyme gene. METHODS: Diabetic and non-diabetic mice harboring 2 or 3 copies of the angiotensin-converting enzyme gene were used in the present study. Animals were divided into 4 groups: diabetic groups with two and three copies of the angiotensin-converting enzyme gene (2CD and 3CD) and the respective age-matched non-diabetic groups (2C and 3C). Hemodynamic, cardiovascular, and autonomic parameters as well as renal Ang II expression were evaluated. RESULTS: Heart rate was lower in diabetic animals than in non-diabetic animals. Autonomic modulation analysis indicated that the 3CD group showed increased sympathetic modulation and decreased vagal modulation of heart rate variability, eliciting increased cardiac sympathovagal balance, compared with all the other groups. Concurrent diabetes and either angiotensin-converting enzyme polymorphism resulted in a significant increase in Ang II expression in the renal cortex. CONCLUSION: Data indicates that a small increase in angiotensin-converting enzyme activity in diabetic animals leads to greater impairment of autonomic function, as demonstrated by increased sympathetic modulation and reduced cardiac vagal modulation along with increased renal expression of Ang II.

ACE gene dosage determines additional autonomic dysfunction and increases renal angiotensin II levels in diabetic mice

OBJECTIVES: The present study aimed to investigate cardiovascular autonomic modulation and angiotensin II (Ang II) activity in diabetic mice that were genetically engineered to harbor two or three copies of the angiotensin-converting enzyme gene. METHODS: Diabetic and non-diabetic mice harboring 2 or 3 copies of the angiotensin-converting enzyme gene were used in the present study. Animals were divided into 4 groups: diabetic groups with two and three copies of the angiotensin-converting enzyme gene (2CD and 3CD) and the respective age-matched non-diabetic groups (2C and 3C). Hemodynamic, cardiovascular, and autonomic parameters as well as renal Ang II expression were evaluated. RESULTS: Heart rate was lower in diabetic animals than in non-diabetic animals. Autonomic modulation analysis indicated that the 3CD group showed increased sympathetic modulation and decreased vagal modulation of heart rate variability, eliciting increased cardiac sympathovagal balance, compared with all the other groups. Concurrent diabetes and either angiotensin-converting enzyme polymorphism resulted in a significant increase in Ang II expression in the renal cortex. CONCLUSION: Data indicates that a small increase in angiotensin-converting enzyme activity in diabetic animals leads to greater impairment of autonomic function, as demonstrated by increased sympathetic modulation and reduced cardiac vagal modulation along with increased renal expression of Ang II.

Interaction between Na-K-ATPase and Bcl-2 proteins BclXL and Bak.

In silico analysis predicts interaction between Na-K-ATPase (NKA) and Bcl-2 protein canonical BH3- and BH1-like motifs, consistent with NKA inhibition by the benzo-phenanthridine alkaloid chelerythrine, a BH3 mimetic, in fetal human lens epithelial cells (FHLCs) (Lauf PK, Heiny J, Meller J, Lepera MA, Koikov L, Alter GM, Brown TL, Adragna NC. Cell Physiol Biochem 31: 257-276, 2013). This report establishes proof of concept: coimmunoprecipitation and immunocolocalization showed unequivocal and direct physical interaction between NKA and Bcl-2 proteins. Specifically, NKA antibodies (ABs) coimmunoprecipitated BclXL (B-cell lymphoma extra large) and BAK (Bcl-2 antagonist killer) proteins in FHLCs and A549 lung cancer cells. In contrast, both anti-Bcl-2 ABs failed to pull down NKA. Notably, the molecular mass of BAK1 proteins pulled down by NKA and BclXL ABs appeared to be some 4-kDa larger than found in input monomers. In silico analysis predicts these higher molecular mass BAK1 proteins as alternative splicing variants, encoding 42 amino acid (aa) larger proteins than the known 211-aa long canonical BAK1 protein. These BAK1 variants may constitute a pool separate from that forming mitochondrial pores by specifically interacting with NKA and BclXL proteins. We propose a NKA-Bcl-2 protein ternary complex supporting our hypothesis for a special sensor role of NKA in Bcl-2 protein control of cell survival and apoptosis.

Influência da integridade dos barorreceptores nos ajustes morfofuncionais cardíacos à hipertensão espontânea em ratos / Influence of baroreceptor integrity on cardiac morpho-functional adjustments to spontaneous hypertension in rats

Tem sido demonstrado que a redução da sensibilidade do barorreflexo é um marcador independente de risco de mortalidade. O barorreflexo arterial tem um papel importante na manutenção e na estabilidade da pressão arterial (PA) momento a momento. Embora a variabilidade da pressão arterial (VPA) seja conhecida como contribuinte para a morbidade e mortalidade, os mecanismos pelos quais a VPA causa lesões de órgãos alvo ainda não estão bem entendidos. No presente estudo, testamos a hipótese de que o prejuízo do barorreflexo, com ou sem o aumento da PA, pode induzir o remodelamento cardíaco e da artéria pulmonar por alterar a modulação autonômica comandada pelos barorreceptores arteriais sobre coração e vasos. Para tanto, foi investigado em ratos normotensos e hipertensos o efeito da disfunção barorreflexa (10 semanas após desnervação sinoaórtica- DSA) nas alterações hemodinâmicas, no remodelamento cardíaco e no remodelamento da artéria pulmonar. A função e a morfologia cardíaca de ratos machos Wistar e SHR (GN e GH) foram avaliadas pelo ecocardiograma e por histologia. A pressão arterial foi gravada diretamente. A hipertrofia ventricular foi expressa pela relação entre peso doventrículo esquerdo (VE) e peso do ventrículo direito (VD) pelo peso corporal do rato (PC). A VPA foi avaliada pelo domínio do tempo e da freqüência. A expressão gênica pela quantificação do mRNA do peptídio natriurérito (ANP), da alfa-actina esquelética (-actina), do colágeno tipo I e tipo III foi avaliada pelo RT-PCR. A PA estava maior no grupo SHR quando comparada ao normotenso, mas a DSA não alterou os valores de PA nos grupos normotenso e hipertenso. A VPA sistólica mostrou-se maior nos grupos com DSA. Como esperado, a resposta barorreflexa estava reduzida nos grupos com DSA. Os componentes LF e HF da VFC estavam maiores nos grupos GH e GHD. Entretanto, o componente HF da VFC estava menor em GHD quando comparado ao GH. O tempo de aceleração da artéria pulmonar estava reduzido nos...

It has been demonstrated that reduced baroreflex sensitivity is an independent marker of mortality risk. The arterial baroreflex plays an important role in the maintenance of the moment-to-moment stability of blood pressure (BP). Although the contribution of blood pressure variability (BPV) to cardiovascular morbidity and mortality is well established, the mechanisms by which BPV causes end-organ damage process are still unknown. In the present study, we hypothesized that baroreflex impairment, with or without increase in BP, can induce cardiac and pulmonary artery remodeling by altering the autonomic modulation controlled by the arterial baroreceptors to the heart and vessels. For these purposes, it were investigated in normotensive and hypertensive rats the effects of baroreceptors dysfunction (10 weeks after sinoaortic denervation - SAD) on hemodynamic alterations and on cardiac and pulmonary arterial remodeling. Cardiac function and morphology of male normotensive Wistar (GN) and spontaneously hyperntensive (GH) intact rats which underwent SAD (GD and GHD, respectively) were assessed by echocardiography and histology. BP was directly recorded. Ventricular hypertrophy was quantified by the ratio of left ventricular weight (LVW) and right ventricular weight (RVW) to body weight (BW). BPV was quantified in the time and frequency domains. The natriuretic peptide (ANP), alpha-skeletal actin (-skelectal), collagen type I and type III genes mRNA expressions were evaluated by RT-PCR. SHR presented higher BP than Wistar rats, but SAD did not change BP values either in normotensive or in hypertensive groups. Systolic BPV was increased in both SAD groups. As expected, baroreflex responses were reduced in both SAD groups. LF and HF components of HRV were increased in GH and GHD groups. However, HF component of HRV was increased in GHD as compared to GH. The pulmonary artery acceleration time was reduced in both SAD groups. In addition, SAD impaired diastolic...

Renin angiotensin system and cardiac hypertrophy after sinoaortic denervation in rats.

OBJECTIVE: The aim of this study was to evaluate the role of angiotensin I, II and 1-7 on left ventricular hypertrophy of Wistar and spontaneously hypertensive rats submitted to sinoaortic denervation. METHODS: Ten weeks after sinoaortic denervation, hemodynamic and morphofunctional parameters were analyzed, and the left ventricle was dissected for biochemical analyses. RESULTS: Hypertensive groups (controls and denervated) showed an increase on mean blood pressure compared with normotensive ones (controls and denervated). Blood pressure variability was higher in denervated groups than in their respective controls. Left ventricular mass and collagen content were increased in the normotensive denervated and in both spontaneously hypertensive groups compared with Wistar controls. Both hypertensive groups presented a higher concentration of angiotensin II than Wistar controls, whereas angiotensin 1-7 concentration was decreased in the hypertensive denervated group in relation to the Wistar groups. There was no difference in angiotensin I concentration among groups. CONCLUSION: Our results suggest that not only blood pressure variability and reduced baroreflex sensitivity but also elevated levels of angiotensin II and a reduced concentration of angiotensin 1-7 may contribute to the development of left ventricular hypertrophy. These data indicate that baroreflex dysfunction associated with changes in the renin angiotensin system may be predictive factors of left ventricular hypertrophy and cardiac failure.

Exercise training associated with estrogen therapy induced cardiovascular benefits after ovarian hormones deprivation.

Menopause is recognized as a period of increased risk for coronary heart disease. Although the benefits of exercise training in lowering cardiovascular risk factors are well established, the risks and benefits of hormone therapy have been questioned. The purpose of the present study was to investigate the effects of estrogen therapy (HT) associated or not with exercise training (ET) in autonomic cardiovascular control in ovariectomized (OVX) rats. Female rats were divided into: control, OVX, OVX+HT, OVX+ET and OVX+HT+ET. HT was performed using a 0.25mg 8-weeks sustained release pellet. Trained groups were submitted to an 8-week exercise training protocol on treadmill. Baroreflex sensitivity (BRS) was evaluated by heart rate responses to arterial pressure (AP) changes, and vagal and sympathetic tonus by pharmacological blockade. Ovariectomy induced an AP increase (123+/-2mmHg vs. 108+/-2mmHg), BRS impairment ( approximately 69%), sympathetic activation ( approximately 100%) and vagal tonus reduction ( approximately 77%) compared to controls. HT or ET normalized the changes in parasympathetic tonus. However, only the association HT+ET was able to promote normalization of AP, BRS and sympathetic tonus, as compared to controls. These results indicate that ET induces cardiovascular and autonomic benefits in OVX rats under HT, suggesting a positive role of this association in the management of cardiovascular risk factor in postmenopausal women.

Renin angiotensin system and cardiac hypertrophy after sinoaortic denervation in rats

OBJECTIVE: The aim of this study was to evaluate the role of angiotensin I, II and 1-7 on left ventricular hypertrophy of Wistar and spontaneously hypertensive rats submitted to sinoaortic denervation. METHODS: Ten weeks after sinoaortic denervation, hemodynamic and morphofunctional parameters were analyzed, and the left ventricle was dissected for biochemical analyses. RESULTS: Hypertensive groups (controls and denervated) showed an increase on mean blood pressure compared with normotensive ones (controls and denervated). Blood pressure variability was higher in denervated groups than in their respective controls. Left ventricular mass and collagen content were increased in the normotensive denervated and in both spontaneously hypertensive groups compared with Wistar controls. Both hypertensive groups presented a higher concentration of angiotensin II than Wistar controls, whereas angiotensin 1-7 concentration was decreased in the hypertensive denervated group in relation to the Wistar groups. There was no difference in angiotensin I concentration among groups. CONCLUSION: Our results suggest that not only blood pressure variability and reduced baroreflex sensitivity but also elevated levels of angiotensin II and a reduced concentration of angiotensin 1-7 may contribute to the development of left ventricular hypertrophy. These data indicate that baroreflex dysfunction associated with changes in the renin angiotensin system may be predictive factors of left ventricular hypertrophy and cardiac failure.

Role of exercise training in cardiovascular autonomic dysfunction and mortality in diabetic ovariectomized rats.

Diabetes and menopause markedly increase the risk of cardiovascular disease in women. The objective of the present study was to investigate the effects of exercise training on cardiovascular autonomic dysfunction and on total mortality in diabetic female rats undergoing ovarian hormone deprivation. Female Wistar rats were divided into ovariectomized groups: sedentary and trained controls and sedentary and trained diabetic rats (streptozotocin, 50 mg/kg IV). Trained groups were submitted to an exercise training protocol on a treadmill (8 weeks). The baroreflex sensitivity was evaluated by heart rate responses to arterial pressure changes. Heart rate variability was determined using the SD of the basal heart rate. Vagal and sympathetic tonus were evaluated by pharmacological blockade. Diabetes impaired baroreflex sensitivity ( approximately 55%), vagal tonus ( approximately 68%), and heart rate variability ( approximately 38%). Exercise training improved baroreflex sensitivity and heart rate variability in control and diabetic groups in relation to their sedentary groups. Trained control rats presented increased vagal tonus compared with that of sedentary ones. The sympathetic tonus was reduced in the trained diabetic group as compared with that of other studied groups. Significant correlations were obtained between heart rate variability and vagal tonus with baroreflex sensitivity. Mortality, assessed during the training period, was reduced in trained diabetic (25%) rats compared with mortality in sedentary diabetic rats (60%). Together, these findings suggest that decreases in baroreflex sensitivity and heart rate variability may be related to increased mortality in female diabetic subjects and that improved autonomic regulation induced by exercise training may contribute to decreased mortality in this population.

Efeitos da suplementação do 17beta-estradiol no dano oxidativo cardíaco de ratas submetidas à privação dos hormônios ovarianos / Effects of 17beta-estradiol replacement on cardiac oxidative damage in rats submitted to ovarian hormone deprivation

OBJETIVO: avaliar o estresse oxidativo em tecido cardíaco de ratas ooforectomizadas, com ou sem terapia hormonal. MÉTODOS: ratas Wistar foram divididas em três grupos: grupo controle (GC), grupo ooforectomizada (GO) e grupo ooforectomizada + suplementação hormonal (GOS). A privação estrogênica foi obtida pela ooforectomia bilateral. Uma semana após a ooforectomia, um pellet de 1,5 mg de 17beta-estradiol foi implantado nos animais do grupo GOS. Nove semanas após a ooforectomia, o tecido cardíaco foi obtido para a análise do estresse oxidativo por meio da medida da quimiluminescência e da atividade das enzimas antioxidantes catalase (CAT), superóxido dismutase (SOD) e glutationa peroxidase (GPx). RESULTADOS: a quimiluminescência estava aumentada no GO (7348±312 cps/mg proteína) quando comparado ao GC (6250±41 cps/mg proteína, p<0,01), mas não houve diferença significante entre GC e GOS (6170±237 cps/mg proteína). A ooforectomia reduziu a atividade da SOD (22 por cento, p<0,001) e da CAT (35 por cento, p<0,05) no GO comparado ao GC. A terapia hormonal normalizou a atividade das enzimas antioxidantes no GOS. Não houve significância estatística na atividade da GPx quando os grupos estudados foram comparados. CONCLUSÕES: a privação dos hormônios ovarianos induziu aumento do estresse oxidativo e redução das defesas antioxidantes no tecido cardíaco. No entanto, a terapia hormonal preveniu o estresse oxidativo após a ooforectomia, provavelmente devido a um aumento das enzimas CAT e SOD no músculo cardíaco. Esses achados sugerem uma importante participação do estresse oxidativo nas disfunções cardiovasculares observadas em mulheres após a menopausa, reforçando a importância da terapia hormonal para o manejo dos riscos de doenças cardiovasculares neste grupo de mulheres.

PURPOSE: to evaluate oxidative stress in cardiac tissue of ovariectomized rats, with and without hormonal therapy. METHODS: female Wistar rats were divided in three groups: control group (CG); ovariectomized group (OG); ovariectomized group with estrogen supplementation (ESG). The estrogen deprivation was done through bilateral ovariectomy. After one week from the ovariectomy, a pellet of 1.5 mg of 17beta-estradiol was implanted in the ESG animals. Nine weeks after the ovariectomy, cardiac tissue was obtained for the analysis of the oxidative stress through CL (chemiluminescence), and measurement of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and gluthatione peroxidase (GPx). RESULTS: CL was increased in the OG (7348±312 cps/mg protein) when compared with the CG (6250±41 cps/mg protein, p<0.01), but there was no significant difference between the CG and the ESG (6170±237 cps/mg protein). Ovariectomy reduced SOD (35 percent, p<0.05) and CAT (22 percent, p<0.001) activities in the OG as compared with the CG. Hormonal therapy normalized antioxidant enzymes activities in the ESG. There was no statistically significant difference in GPx activity among the groups studied. CONCLUSIONS: ovarian hormone deprivation induced an increase of oxidative stress with reduction of antioxidant defenses in the cardiac tissue. However, hormonal therapy prevented oxidative stress after ovariectomy, probably due to an increase of the CAT and SOD activities in the cardiac muscle. These findings suggest an important oxidative stress contribution in cardiovascular dysfunctions observed in women after menopause, reinforcing the importance of hormonal therapy in the management of cardiovascular diseases risk in this group of women.

Exercise training improves baroreflex sensitivity associated with oxidative stress reduction in ovariectomized rats.

The protection from coronary events that young women have is sharply reduced at menopause. Oxidative stress and baroreflex sensitivity impairment of the circulation have been demonstrated to increase cardiovascular risk. On the other hand, exercise training has been indicated as a nonpharmacological treatment for many diseases. The aim of the present study was to test the hypothesis that exercise training can improve baroreflex sensitivity associated with reduction in oxidative stress in ovariectomized rats, an experimental model of menopause. Exercise training was performed on a treadmill for 8 weeks. Arterial pressure and baroreflex sensitivity, which were evaluated by tachycardic and bradycardic responses to changes in arterial pressure, were monitored. Oxidative stress was evaluated by chemiluminescence and superoxide dismutase and catalase antioxidant enzyme activities. Exercise training reduced resting mean arterial pressure (112+/-2 vs 122+/-3 mm Hg in the sedentary group) and heart rate (325+/-4 vs 356+/-12 bpm in the sedentary group) and also improved baroreflex sensitivity (tachycardic response, 63% and bradycardic response, 58%). Myocardium (25%) and gastrocnemius muscle (48%) chemiluminescence were reduced, and myocardial superoxide dismutase (44%) and gastrocnemius catalase (97%) activities were enhanced in trained rats in comparison with sedentary rats. Myocardium chemiluminescence was positively correlated with systolic arterial pressure (r=0.6) and inversely correlated with baroreflex sensitivity (tachycardic response, r=-0.8 and bradycardic response, r=-0.7). These results indicate that exercise training in ovariectomized rats improves resting hemodynamic status and reflex control of the circulation, probably associated with oxidative stress reduction, suggesting a homeostatic role for exercise training in reducing cardiovascular risk in postmenopausal women.