GPER modulates tone and coronary vascular reactivity in male and female rats

Compared with age-matched men, premenopausal women are largely protected from coronary artery disease, a difference that is lost after menopause. The effects of oestrogens are mediated by the activation of nuclear receptors (ERα and ERβ) and by the G protein-coupled oestrogen receptor (GPER). This study aims to evaluate the potential role of GPER in coronary circulation in female and male rats. The baseline coronary perfusion pressure (CPP) and the concentration-response curve with a GPER agonist (G-1) were evaluated in isolated hearts before and after the blockade of GPER. GPER, superoxide dismutase (SOD-2), catalase and gp91phox protein expression were assessed by Western blotting. Superoxide production was evaluated 'in situ' via dihydroethidium fluorescence (DHE). GPER blockade significantly increased the CPP in both groups, demonstrating the modulation of coronary tone by GPER. G-1 causes relaxation of the coronary bed in a concentration-dependent manner and was significantly higher in female rats. No differences were detected in GPER, SOD-2 and catalase protein expression. However, gp91phox expression and DHE fluorescence were higher in male rats, indicating elevated superoxide production. Therefore, GPER plays an important role in modulating coronary tone and reactivity in female and male rats. The observed differences in vascular reactivity may be related to the higher superoxide production in male rats. These findings help to elucidate the role of GPER-modulating coronary circulation, providing new information to develop a potential therapeutic target for the treatment of coronary heart disease.

Hormonal therapy with estradiol and drospirenone improves endothelium-dependent vasodilation in the coronary bed of ovariectomized spontaneously hypertensive rats

Drospirenone (DRSP) is a progestin with anti-aldosterone properties and it reduces blood pressure in hypertensive women. However, the effects of DRSP on endothelium-dependent coronary vasodilation have not been evaluated. This study investigated the effects of combined therapy with estrogen (E2) and DRSP on endothelium-dependent vasodilation of the coronary bed of ovariectomized (OVX) spontaneously hypertensive rats. Female spontaneously hypertensive rats (n=87) at 12 weeks of age were randomly divided into sham operated (Sham), OVX, OVX treated with E2 (E2), and OVX treated with E2 and DRSP (E2+DRSP) groups. Hemodynamic parameters were directly evaluated by catheter insertion into the femoral artery. Endothelium-dependent vasodilation in response to bradykinin in the coronary arterial bed was assessed using isolated hearts according to a modified Langendorff method. Coronary protein expression of endothelial nitric oxide synthase and estrogen receptor alpha (ER-α) was assessed by Western blotting. Histological slices of coronary arteries were stained with hematoxylin and eosin, and morphometric parameters were analyzed. Oxidative stress was assessed in situ by dihydroethidium fluorescence. Ovariectomy increased systolic blood pressure, which was only prevented by E2+DRSP treatment. Estrogen deficiency caused endothelial dysfunction, which was prevented by both treatments. However, the vasodilator response in the E2+DRSP group was significantly higher at the three highest concentrations compared with the OVX group. Reduced ER-α expression in OVX rats was restored by both treatments. Morphometric parameters and oxidative stress were augmented by OVX and reduced by E2 and E2+DRSP treatments. Hormonal therapy with E2 and DRSP may be an important therapeutic option in the prevention of coronary heart disease in hypertensive post-menopausal women.

Deficiency of sex hormones does not affect 17-ß-estradiol-induced coronary vasodilation in the isolated rat heart

The relaxation of coronary arteries by estrogens in the coronary vascular beds of naive and hypertensive rats has been well described. However, little is known about this action in gonadectomized rats. We investigated the effect of 17-ß-estradiol (E2) in coronary arteries from gonadectomized rats, as well as the contributions of endothelium-derived factors and potassium channels. Eight-week-old female and male Wistar rats weighing 220-300 g were divided into sham-operated and gonadectomized groups (n=9−12 animals per group). The baseline coronary perfusion pressure (CPP) was determined, and the vasoactive effects of 10 μM E2 were assessed by bolus administration before and after endothelium denudation or by perfusion with N^G-nitro-L-arginine methyl ester (L-NAME), indomethacin, clotrimazole, L-NAME plus indomethacin, L-NAME plus clotrimazole or tetraethylammonium (TEA). The CPP differed significantly between the female and sham-operated male animals. Gonadectomy reduced the CPP only in female rats. Differences in E2-induced relaxation were observed between the female and male animals, but male castration did not alter this response. For both sexes, the relaxation response to E2 was, at least partly, endothelium-dependent. The response to E2 was reduced only in the sham-operated female rats treated with L-NAME. However, in the presence of indomethacin, clotrimazole, L-NAME plus indomethacin or L-NAME plus clotrimazole, or TEA, the E2 response was significantly reduced in all groups. These results highlight the importance of prostacyclin, endothelium-derived hyperpolarizing factor, and potassium channels in the relaxation response of coronary arteries to E2 in all groups, whereas nitric oxide may have had an important role only in the sham-operated female group.

Swimming training prevents fat deposition and decreases angiotensin II-induced coronary vasoconstriction in ovariectomized rats

We investigated the effects of chronic swimming training (ST) on the deposition of abdominal fat and vasoconstriction in response to angiotensin II (ANG II) in the coronary arterial bed of estrogen deficient rats. Twenty-eight 3-month old Wistar female rats were divided into 4 groups: sedentary sham (SS), sedentary-ovariectomized (SO), swimming-trained sham (STS) and swimming-trained ovariectomized (STO). ST protocol consisted of a continuous 60-min session, with a 5% BW load attached to the tail, completed 5 days/week for 8-weeks. The retroperitoneal, parametrial, perirenal and inguinal fat pads were measured. The intrinsic heart rate (IHR), coronary perfusion pressure (CPP) and a concentration-response curve to ANG II in the coronary bed was constructed using the Langendorff preparation. Ovariectomy (OVX) significantly reduced 17-β-estradiol plasma levels in SO and STO groups (p<0.05). The STO group had a significantly reduced retroperitoneal and parametrial fat pad compared with the SO group (p<0.05). IHR values were similar in all groups; however, baseline CPP was significantly reduced in the SO, STS and STO groups compared with the SS group (p<0.05). ANG II caused vasoconstriction in the coronary bed in a concentration-dependent manner. The SO group had an increased response to ANG II when compared with all other experimental groups (p<0.05), which was prevented by 8-weeks of ST in the STO group (p<0.05). OVX increased ANG II-induced vasoconstriction in the coronary vascular bed and abdominal fat pad deposition. Eight weeks of swimming training improved these vasoconstrictor effects and decreased abdominal fat deposition in ovariectomized rats.

Roles of estrogen and progesterone in modulating renal nerve function in the rat kidney

The maintenance of extracellular Na⁺ and Cl^- concentrations in mammals depends, at least in part, on renal function. It has been shown that neural and endocrine mechanisms regulate extracellular fluid volume and transport of electrolytes along nephrons. Studies of sex hormones and renal nerves suggested that sex hormones modulate renal function, although this relationship is not well understood in the kidney. To better understand the role of these hormones on the effects that renal nerves have on Na⁺ and Cl^- reabsorption, we studied the effects of renal denervation and oophorectomy in female rats. Oophorectomized (OVX) rats received 17β-estradiol benzoate (OVE, 2.0 mg·kg^-1·day^-1, sc) and progesterone (OVP, 1.7 mg·kg^-1·day^-1, sc). We assessed Na⁺ and Cl^- fractional excretion (FE_Na⁺ and FE_Cl^-, respectively) and renal and plasma catecholamine release concentrations. FE_Na⁺, FE_Cl^-, water intake, urinary flow, and renal and plasma catecholamine release levels increased in OVX vs control rats. These effects were reversed by 17β-estradiol benzoate but not by progesterone. Renal denervation did not alter FE_Na⁺, FE_Cl^-, water intake, or urinary flow values vs controls. However, the renal catecholamine release level was decreased in the OVP (236.6±36.1 ng/g) and denervated rat groups (D: 102.1±15.7; ODE: 108.7±23.2; ODP: 101.1±22.1 ng/g). Furthermore, combining OVX + D (OD: 111.9±25.4) decreased renal catecholamine release levels compared to either treatment alone. OVE normalized and OVP reduced renal catecholamine release levels, and the effects on plasma catecholamine release levels were reversed by ODE and ODP replacement in OD. These data suggest that progesterone may influence catecholamine release levels by renal innervation and that there are complex interactions among renal nerves, estrogen, and progesterone in the modulation of renal function.

The chronic blockade of angiotensin I-converting enzyme eliminates the sex differences of serum cytokine levels of spontaneously hypertensive rats

Sex hormones modulate the action of both cytokines and the renin-angiotensin system. However, the effects of angiotensin I-converting enzyme (ACE) on the proinflammatory and anti-inflammatory cytokine levels in male and female spontaneously hypertensive rats (SHR) are unclear. We determined the relationship between ACE activity, cytokine levels and sex differences in SHR. Female (F) and male (M) SHR were divided into 4 experimental groups each (n = 7): sham + vehicle (SV), sham + enalapril (10 mg/kg body weight by gavage), castrated + vehicle, and castrated + enalapril. Treatment began 21 days after castration and continued for 30 days. Serum cytokine levels (ELISA) and ACE activity (fluorimetry) were measured. Male rats exhibited a higher serum ACE activity than female rats. Castration reduced serum ACE in males but did not affect it in females. Enalapril reduced serum ACE in all groups. IL-10 (FSV = 16.4 ± 1.1 pg/mL; MSV = 12.8 ± 1.2 pg/mL), TNF-α (FSV = 16.6 ± 1.2 pg/mL; MSV = 12.8 ± 1 pg/mL) and IL-6 (FSV = 10.3 ± 0.2 pg/mL; MSV = 7.2 ± 0.2 pg/mL) levels were higher in females than in males. Ovariectomy reduced all cytokine levels and orchiectomy reduced IL-6 but increased IL-10 concentrations in males. Castration eliminated the differences in all inflammatory cytokine levels (IL-6 and TNF-α) between males and females. Enalapril increased IL-10 in all groups and reduced IL-6 in SV rats. In conclusion, serum ACE inhibition by enalapril eliminated the sexual dimorphisms of cytokine levels in SV animals, which suggests that enalapril exerts systemic anti-inflammatory and anti-hypertensive effects.

Tributyltin impairs the coronary vasodilation induced by 17β-estradiol in isolated rat heart

Triorganotins, such as tributyltin (TBT), are environmental contaminants that are commonly used as antifouling agents for boats. However, TBT is also known to alter mammalian reproductive functions. Although the female sex hormones are primarily involved in the regulation of reproductive functions, 17β-estradiol also protects against cardiovascular diseases, in that this hormone reduces the incidence of coronary artery disease via coronary vasodilation. The aim of this study was to examine the influence of 100 ng/kg TBT administered daily by oral gavage for 15 d on coronary functions in female Wistar rats. Findings were correlated with changes in sex steroids concentrations. Tributyltin significantly increased the baseline coronary perfusion pressure and impaired vasodilation induced by 17β-estradiol. In addition, TBT markedly decreased serum 17β-estradiol levels accompanied by a significant rise in serum progesterone levels. Tributyltin elevated collagen deposition in the heart interstitium and number of mast cells proximate to the cardiac vessels. There was a positive correlation between the increase in coronary perfusion pressure and incidence of cardiac hypertrophy. In addition, TBT induced endothelium denudation (scanning electron microscopy) and accumulation of platelets. Moreover, TBT impaired coronary vascular reactivity to estradiol (at least in part), resulting in endothelial denudation, enhanced collagen deposition and elevated number of mast cells. Taken together, the present results demonstrate that TBT exposure may be a potential risk factor for cardiovascular disorders in rats.

Role of the renin–angiotensin system in the nandrolone-decanoate-induced attenuation of the Bezold–Jarisch reflex

The androgen nandrolone decanoate (ND) is known to cause cardiovascular abnormalities, such as attenuation of the Bezold–Jarisch Reflex (BJR), cardiac hypertrophy, and elevation of mean arterial pressure (MAP). Futhermore, a relationship between androgens and the renin–angiotensin system (RAS) has been reported. The purpose of this study was to evaluate the influence of RAS on the BJR, cardiac and prostatic hypertrophy, and MAP evoked by ND. For this, male Wistar rats were treated with ND (10 mg·(kg body mass)–1 for 8 weeks; DECA), or vehicle (control animals; CON), or enalapril (10 mg·(kg body mass)–1, daily; CONE), or ND and enalapril (10 mg ND + 10 mg enalapril per kilogram of body mass; DECAE). After 8 weeks of treatment, the BJR was evaluated by bradycardia and hypotensive responses that were elicited by serotonin administration (2–32 µg·(kg body mass)–1). MAP was assessed; cardiac and prostate hypertrophy were determined by the ratio of the tissue mass:body mass, and by histological analysis of the heart. Animals from the DECA group showed prostatic and cardiac hypertrophy, elevation in mean arterial pressure, and an impairment of BJR. Co-treatment with enalapril inhibited these changes. The data from the present study suggest that RAS has an impact on BJR attenuation, cardiac and prostatic hypertrophy, and the elevation in MAP evoked by ND.

Sex differences in the coronary vasodilation induced by 17 β-oestradiol in the isolated perfused heart from spontaneously hypertensive rats

AIM

The relaxation induced by oestrogen in the coronary vascular bed from normotensive rats has been well described. However, almost nothing is known about this action in spontaneously hypertensive rats (SHR). We investigated the effect of 17 β-oestradiol (E(2) ) in coronary arteries from SHR as well as the contribution of the endothelium and the vascular smooth muscle to this action.

METHODS

Coronary arteries from male and female rats were used. Mean arterial pressure (MAP) and baseline coronary perfusion pressure (CPP) were determined. The effects of 10 μm E(2) were assessed by in bolus administration before and after endothelium denudation (0.25 μm sodium deoxycholate) or perfusion with 100 μm N(ω)-nitro-L-arginine methyl ester (L-NAME), 2.8 μm indomethacin, 0.75 μm clotrimazole, 100 μm L-NAME after endothelium denudation (0.25 μm sodium deoxycholate), 100 μm L-NAME plus 2.8 μm indomethacin, 0.75 μm clotrimazole plus 2.8 μm indomethacin and 4 mm tetraethylammonium (TEA).

RESULTS

  MAP was higher in the male group, while CPP was higher in the female group (P<0.05). There were no differences in E(2)-induced relaxation between females and males (-17±1.6 vs. -17±2% respectively). Only in the female group the E(2) response was significantly attenuated after endothelium removal or perfusion with clotrimazole. The response to E(2) was reduced in both groups with L-NAME, L-NAME plus indomethacin, L-NAME after endothelium removal or TEA.

CONCLUSIONS

Nitric oxide, endothelium-derived hyperpolarizing factor and potassium channels may have the most important role to E(2) response in the female group, whereas nitric oxide and potassium channels may have the most important role in the male group.

Uso crônico de decanoato de nandrolona como fator de risco para hipertensão arterial pulmonar em ratos Wistar

INTRODUÇÃO: O uso indiscriminado de esteróides anabolizantes sintéticos, análogos à testosterona, implica aumento do risco cardiovascular e hipertrofia cardíaca. Assim, o aumento da massa ventricular direita corrigido pelo peso corporal (i.é., hipertrofia ventricular direita - HVD), poderia elevar o risco para o desenvolvimento de hipertensão arterial pulmonar (HAP). OBJETIVOS: Examinar os efeitos do tratamento em longo prazo com decanoato de nadrolona na HVD e sua relação com a HAP em ratos. MÉTODOS: 16 ratos Wistar com três meses de idade foram aleatoriamente divididos em dois grupos: 1) controle-sham (CONT, n = 8); 2) tratados com decanoato de nandrolona (DECA, n = 8). O tratamento consistiu na aplicação intramuscular de Deca-durabolin® 6.0mg.kg-1 de peso corporal durante quatro semanas. Após tratamento, os animais foram anestesiados com hidrato de cloral (4.0mL.kg-1, i.p.), submetidos à cateterização da artéria femoral para registro da pressão arterial media (PAM) e frequência cardíaca (FC). O coração, os rins e o fígado foram retirados, pesados e avaliados os índices de hipertrofia, os quais foram calculados pela razão da massa do órgão pelo peso corporal (mg.g-1). RESULTADOS: Os animais tratados com DECA apresentaram aumento (p < 0,01) do peso corporal (338 ± 6g) vs. CONT (315 ± 5g). Não houve alterações da PAM, embora houvesse (p < 0,01) bradicardia nos animais tratados com DECA (321 ± 13bpm) vs. CONT (368 ± 11bpm). Verificou-se significativa (p < 0,01) hipertrofia dos ventrículos e rins, mas não no fígado. A correlação entre a HVD e PAM no grupo DECA apresentou coeficiente de Pearson positivo e maior (r² = 0,4013) quando comparado com o controle (r² = 0,0003). CONCLUSÕES: Esses dados demonstram que o uso em longo prazo de decanoato de nandrolona induz importante bradicardia e HVD, o que sugere aumento do risco para HAP.

Glycemic and urinary volume responses in diabetic mellitus rats treated with Solanum lycocarpum

Dietary fiber performs important functions in diabetes mellitus control and treatment. In this study, we evaluate the reduction in plasma glucose after the treatment of diabetic rats with high-fiber Solanum lycocarpum flour. We found that serum glucose, water and food intake, urine excretion, and urine sodium concentration were reduced in S. lycocarpum flour-treated diabetic rats (TDRs), compared with diabetic control rats (DCRs). In addition, TDRs did not show signs of kidney hypertrophy, unlike those in the DCR group. These results suggest that the use of S. lycocarpum flour can be an effective support in diabetes mellitus treatment.

Ultrasound lipoclasia on subcutaneous adipose tissue to produce acute hyperglycemia and enhance acute inflammatory response in healthy female rats

BACKGROUND

Ultrasound lipoclasia (USL) on white adipose tissue (WAT) has been largely used in the treatment of cellulite. Nevertheless, the acute consequences of this therapy on metabolism and biochemical profile are significant and should be taken into account.

OBJECTIVES

To analyze the acute metabolic effects of USL in WAT of healthy rats using analyses of body composition, biochemical profile, and inflammatory markers.

METHODS

Female Wistar rats weighing approximately 250 g were divided into two groups (n=10 each): control and treated. The treated group was submitted to USL, a single 3-MHz ultrasound application (5.6 W/cm(2)), in gluteal-femoral WAT (3 cm(2)) for 3 minutes. Animals were subjected to glycemic control. Body composition was analyzed using bio-impedance, and lipid profile, insulinemia, C-reactive protein (CRP), and lactate dehydrogenase (LDH) were measured.

RESULTS

USL reduced (p<.05) body fat mass. The basal metabolic rate was found to have increased (p<.05). Basal insulin and the lipoprotein profile were not different, although the glycemic curve and CRP and LDH (p<.05) levels were higher.

CONCLUSIONS

Fat mobilization using USL provokes acute hyperglycemia and enhances an acute inflammatory response, producing cardiometabolic risk in female rats.

Efeitos agudos do alongamento estático no desempenho da força dinâmica em homens jovens

INTRODUÇÃO: O alongamento muscular é frequentemente utilizado nas práticas desportivas, com o objetivo de aumentar a flexibilidade muscular e amplitude articular, assim como diminuir o risco de lesões e melhorar o desempenho atlético. OBJETIVO: Analisar o efeito agudo do alongamento com diferentes tempos no desempenho da força dinâmica de membros superiores e inferiores em homens jovens. MÉTODOS: Participaram da amostra 14 voluntários do sexo masculino com idade de 23 ± 2 anos, peso corporal de 84 ± 10kg, estatura de178 ± 7cm, IMC de 26 ± 2kg/m² e percentual de gordura de 11 ± 3%. Eles foram avaliados com o teste de 10RM em três situações distintas: condição sem alongamento (SA), aquecimento especifico seguido do teste de 10-RM; condição com oito minutos de alongamento (AL-8), uma sessão de alongamento estático com oito minutos de duração, seguido do aquecimento e teste de 10RM; e a condição alongamento 16 minutos (AL-16), 16 minutos de alongamento seguidos dos procedimentos descritos anteriormente. Os testes foram feitos no supino reto e leg-press 45º; os alongamentos foram selecionados de forma a atingir as musculaturas solicitadas nos respectivos exercícios. RESULTADOS: Houve redução de 9,2% da força muscular dinâmica de membros superiores em comparação dos grupos SA e AL16, e entre os grupos AL8 e AL16 (p < 0,001). Em membros inferiores essa redução de força (p < 0,001) foi de 4,8% para AL-8 e de 14,3% para AL-16 em comparação com o grupo SA. CONCLUSÃO: Sessões de alongamentos estáticos efetuados antes de atividades que envolvam força dinâmica possuem a capacidade de alterar negativamente o desempenho dessa qualidade física, acarretando pior rendimento em longos períodos de alongamento.

Influence of He-Ne laser therapy on the dynamics of wound healing in mice treated with anti-inflammatory drugs

We determined the effects of helium-neon (He-Ne) laser irradiation on wound healing dynamics in mice treated with steroidal and non-steroidal anti-inflammatory agents. Male albino mice, 28-32 g, were randomized into 6 groups of 6 animals each: control (C), He-Ne laser (L), dexamethasone (D), D + L, celecoxib (X), and X + L. D and X were injected im at doses of 5 and 22 mg/kg, respectively, 24 h before the experiment. A 1-cm long surgical wound was made with a scalpel on the abdomens of the mice. Animals from groups L, D + L and X + L were exposed to 4 J (cm(2))-1 day-1 of He-Ne laser for 12 s and were sacrificed on days 1, 2, or 3 after the procedure, when skin samples were taken for histological examination. A significant increase of collagen synthesis was observed in group L compared with C (168 +/- 20 vs 63 +/- 8 mm(2)). The basal cellularity values on day 1 were: C = 763 +/- 47, L = 1116 +/- 85, D = 376 +/- 24, D + L = 698 +/- 31, X = 453 +/- 29, X + L = 639 +/- 32 U/mm(2). These data show that application of L increases while D and X decrease the inflammatory cellularity compared with C. They also show that L restores the diminished cellularity induced by the anti-inflammatory drugs. We suggest that He-Ne laser promotes collagen formation and restores the baseline cellularity after pharmacological inhibition, indicating new perspectives for laser therapy aiming to increase the healing process when anti-inflammatory drugs are used.

EFFECT OF ENALAPRIL TREATMENT ON THE SENSITIVITY OF CARDIOPULMONARY REFLEXES IN RATS WITH MYOCARDIAL INFARCTION

1. The aim of the present study was to evaluate the effect of treatment with enalapril on the sensitivity of cardiopulmonary reflexes 30 days after myocardial infarction in Wistar rats. 2. Animals were divided into four groups: (i) sham operated, receiving vehicle (SHAM); (ii) infarcted, receiving vehicle (0.9% NaCl; INF); (iii) sham operated, receiving enalapril (SHAME); and (iv) infarcted, receiving enalapril (INFE). 3. Enalapril was administered at a dose of 10 mg/kg per day. Serotonin (4-32 microg/kg, i.v.) was administered in order to activate the Bezold-Jarisch reflex, which was estimated as the percentage of reduction in heart rate. 4. The volume-sensitive cardiopulmonary reflex was induced by saline overload and evaluated as the percentage increase in sodium and volume renal excretion. At the end of the experiments, rats were killed and hearts excised to estimate the size of the infarction. The weight of the kidneys, lungs, liver and cardiac chambers as ratios of bodyweight was used to estimate the extent of hypertrophy. 5. The results showed an impairment in the sensitivity of the cardiopulmonary reflexes in the INF group compared with the SHAM and SHAME groups. We observed right ventricle and pulmonary hypertrophy, a reduction in mean and systolic arterial pressure and an increase in heart rate in INF animals. In the INFE group, nearly all the parameters were normal compared with the INF group, except for systolic arterial pressure, which was only partially improved. 6. The main finding of the present study was that treatment with enalapril normalized the sensitivity of the cardiopulmonary reflexes, which could be due, in part, to the reduction of cardiac hypertrophy. The present study provides information about the beneficial effects of the angiotensin-converting enzyme inhibitors by normalizing the cardiopulmonary reflexes involved with the regulation of volume and sodium, as well as control of arterial pressure and heart rate in infarcted animals.

Utilização da terapia ultra-sônica de baixa intensidade na redução da lipodistrofia ginecóide: uma terapia segura ou risco cardiovascular transitório? Um estudo pré-clínico

FUNDAMENTOS: A difusão do ultra-som (US) como método terapêutico corroborou o perfil de segurança observado na prática médica, porém nem sempre baseado em estudos sistemáticos, sugerindo medidas de cautela e otimização da técnica. OBJETIVO: Avaliar o risco potencial da utilização do ultra-som de baixa intensidade em terapias dermatológicas e estéticas e suas implicações no sistema cardiovascular. MÉTODOS: Utilizaram-se (n=10) ratas Wistar, pesando +300g e divididas em dois grupos: controle-Sham e terapia ultra-sônica (TUS). Após anestesia induzida por halotano, as fêmeas foram submetidas à TUS modo de pulso, com potência de 1W/cm² e 3MHz freqüência, na região inguinal em área de 3cm², durante três minutos por 10 dias. Ao final do tratamento, após anestesia com (cloral hidratado 10% / 0,4ml/100g), foram cateterizadas em artéria femoral, e mensuradas a pressão arterial média (PAM) e a freqüência cardíaca (FC); foi coletado sangue para dosagem do perfil lipídico e glicêmico. A seguir, o coração foi isolado e perfundido pelo método de Langendorff; após 40 minutos, foi determinada a pressão de perfusão coronariana (PPC) basal e realizada curva dose-resposta de adenosina. Realizada Anova, seguida do teste de Tukey para múltiplas comparações, e as diferenças foram estabelecidas em 5%, e os valores expressos como média + EPM. RESULTADOS: Observou-se aumento (P<0,01) da PAM no grupo TUS (114+1 vs 103+1 mmHg) quando comparado ao grupo controle. A glicemia em jejum (97+2 vs 133+6 mg/dL) e o perfil lipídico apresentaram diferenças significativas tais como no LDL (10+1 vs 14+1mg/dL), HDL (59+1 vs 54+1mg/dL), triglicérides (33+2 vs 82+6mg/dL) nos grupos controle e TUS, respectivamente. A PPC basal reduziu (P<0,01) de 94+2 mmHg no controle para 79+1 mmHg no TUS. CONCLUSÃO: A TUS, imediatamente após o uso, alterou os parâmetros hemodinâmicos e os níveis de lipídios e glicose séricos, além de produzir atenuação da vasodilatação induzida por adenosina. Pode-se, portanto, considerar que a TUS eleva o risco para eventos cardiovasculares em ratas Wistar.

Endothelial mediators of 17ß-estradiol-induced coronary vasodilation in the isolated rat heart

The present study was designed to determine relaxation in response to 17 beta-estradiol by isolated perfused hearts from intact normotensive male and female rats as well as the contribution of endothelium and its relaxing factors to this action. Baseline coronary perfusion pressure was determined and the vasoactive effects of 17 beta-estradiol (10 microM) were assessed by in bolus administration before and after endothelium denudation by infusion of 0.25 microM sodium deoxycholate or perfusion with 100 microM L-NAME, 2.8 microM indomethacin, 0.75 microM clotrimazole, 100 microM L-NAME plus 2.8 microM indomethacin, and 100 microM L-NAME plus 0.75 microM clotrimazole. Baseline coronary perfusion pressure differed significantly between males (84 +/- 2 mmHg, N = 61) and females (102 +/- 2 mmHg, N = 61). Bolus injection of 10 microM 17 beta-estradiol elicited a transient relaxing response in all groups, which was greater in coronary beds from females. For both sexes, the relaxing response to 17 beta-estradiol was at least in part endothelium-dependent. In the presence of the nitric oxide synthase inhibitor L-NAME, the relaxing response to 17 beta-estradiol was reduced only in females. Nevertheless, in the presence of indomethacin, a cyclooxygenase inhibitor, or clotrimazole, a cytochrome P450 inhibitor, the 17 beta-estradiol response was significantly reduced in both groups. In addition, combined treatment with L-NAME plus indomethacin or L-NAME plus clotrimazole also reduced the 17 beta-estradiol response in both groups. These results indicate the importance of prostacyclin and endothelium-derived hyperpolarizing factor in the relaxing response to 17 beta-estradiol. 17 beta-estradiol-induced relaxation may play an important role in the regulation of coronary tone and this may be one of the reasons why estrogen replacement therapy reduces the risk of coronary heart disease in postmenopausal women.

Oral administration of L-arginine decreases blood pressure and increases renal excretion of sodium and water in renovascular hypertensive rats

The two-kidney, one-clip renovascular (2K1C) hypertension model is characterized by a reduction in renal flow on the clipped artery that activates the renin-angiotensin system. Endothelium dysfunction, including diminished nitric oxide production, is also believed to play a role in the pathophysiology of this model. Some studies have shown an effect of L-arginine (L-Arg, a nitric oxide precursor) on hypertension. In the present study we determined the ability of L-Arg (7 days of treatment) to reduce blood pressure and alter renal excretions of water, Na+ and K+ in a model of 2K1C-induced hypertension. Under ether anesthesia, male Wistar rats (150-170 g) had a silver clip (0.20 mm) placed around the left renal artery to produce the 2K1C renovascular hypertension model. In the experimental group, the drinking water was replaced with an L-Arg solution (10 mg/ml; average intake of 300 mg/day) from the 7th to the 14th day after surgery. Sham-operated rats were used as controls. At the end of the treatment period, mean blood pressure was measured in conscious animals. The animals were then killed and the kidneys were removed and weighed. There was a significant reduction of mean blood pressure in the L-Arg-treated group when compared to control (129 7 vs 168 6 mmHg, N = 8-10 per group; P<0.05). Concomitantly, a significant enhancement of water and Na+ excretion was observed in the 2K1C L-Arg-treated group when compared to control (water: 13.0 0.7 vs 9.2 0.5 ml/day, P<0.01; Na+: 1.1 0.05 vs 0.8 0.05 mEq/day, respectively, P<0.01). These results show that orally administered L-Arg acts on the kidney, possibly inducing changes in renal hemodynamics or tubular transport due to an increase in nitric oxide formation.

Sex hormone modulation of serotonin-induced coronary vasodilation in isolated heart

The present study was designed to evaluate the differences in the coronary vasodilator actions of serotonin (5-HT) in isolated heart obtained from naive or castrated male and female rats that were treated with either estrogen or testosterone. Hearts from 12 groups of rats were used: male and female naive animals, castrated, castrated and treated with 17beta-estradiol (0.5 microg kg(-1) day(-1)) for 7 or 30 days, and castrated and treated with testosterone (0.5 mg kg(-1) day(-1)) for 7 or 30 days. After treatment, the vascular reactivity of the coronary bed was evaluated. Baseline coronary perfusion pressure (CPP) was determined and dose-response curves to 5-HT were generated. Baseline CPP differed between male (70 +/- 6 mmHg, N = 10) and female (115 +/- 6 mmHg, N = 12) naive rats. Maximal 5-HT-induced coronary vasodilation was higher (P<0.05) in naive female than in naive male rats. In both sexes, 5-HT produced endothelium-dependent coronary vasodilation. After castration, there was no significant difference in baseline CPP between hearts obtained from male and female rats (75 +/- 7 mmHg, N = 8, and 83 +/- 5 mmHg, N = 8, respectively). Castration reduced the 5-HT-induced maximal vasodilation in female and male rats (P<0.05). Estrogen treatment of castrated female rats restored (P<0.05) the vascular reactivity. In castrated male rats, 30 days of estrogen treatment increased (P<0.05) the responsiveness to 5-HT. The endothelium-dependent coronary vasodilator actions of 5-HT are greater in female rats and are modulated by estrogen. A knowledge of the mechanism of action of estrogen on coronary arteries could aid in the development of new therapeutic strategies and potentially decrease the incidence of cardiovascular disease in both sexes.

Vascular reactivity to methoxamine in conscious sinoaortic denervated rats

Alterations in vascular alpha-adrenoceptor responsiveness following sinoaortic denervation was studied in conscious rats. The arterial hypertension observed in baroreceptor denervated rats decreased progressively during the 30 days of observation. A pressor hyperresponsiveness to methoxamine (10-80 micrograms/kg, iv), was observed 3 to 7 days after baroreceptor denervation followed by a gradual normalization of the vascular reactivity. The results indicate a possible participation of an enhanced alpha 1-adrenoceptor-mediated vasoconstrictor component in the early phase of neurogenic hypertension.

Sex hormone modulation of ventricular hypertrophy in sinoaortic denervated rats

The influence of sex hormones on the development of left ventricular hypertrophy was investigated in baroreceptor-denervated rats. A significant increase (p less than 0.01) in the left ventricular weight/body weight ratio was observed in male but not in female rats 15 days after operation, compared to age- and sex-matched sham-operated rats. This differential hypertrophy occurred despite the development of a significant elevation in arterial blood pressure in both sexes. Castration prior to sinoaortic denervation did not change the level of arterial hypertension but caused a significant reduction (p less than 0.01) in left ventricular weight in male rats and a significant increase (p less than 0.01) in female rats. The pretreatment of male and female sinoaortic denervated and castrated rats with testosterone resulted in ventricular hypertrophy similar to that observed in intact male sinoaortic denervated rats. Pretreatment with estradiol, however, suppressed the left ventricular hypertrophy in intact male rats but did not change the normal ventricular mass observed in intact female sinoaortic denervated rats. These results indicate that the development of left ventricular hypertrophy in sinoaortic denervated rats is modulated by sex hormones, and that testosterone exerts a facilitatory and estradiol an inhibitory action.