DEFAR - Departamento de Farmácia
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/530
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11 resultados
Resultados da Pesquisa
Item DOCA-salt treatment enhances responses to endothelin-1 in murine corpus cavernosum.(2008) Carneiro, Fernando Silva; Vitorino, Fernanda Regina Casagrande Giachini; Lima, Victor Vitorino; Carneiro, Zidonia N.; Nunes, Kenia Pedrosa; Ergul, Adviye; Leite, Romulo; Passaglia, Rita de Cassia Aleixo Tostes; Webb, Robert ClintonThe penis is kept in the flaccid state mainly via a tonic activity of norepinephrine and endothelins (ETs). ET-1 is important in salt-sensitive forms of hypertension. We hypothesized that cavernosal responses to ET-1 are enhanced in deoxycorticosterone acetate (DOCA)-salt mice and that blockade of ETA receptors prevents abnormal responses of the corpus cavernosum in DOCA-salt hypertension. Male C57BL/6 mice were unilaterally nephrectomized and treated for 5 weeks with both DOCA and water containing 1% NaCl and 0.2% KCl. Control mice were uninephrectomized and received tap water with no added salt. Animals received either the ETA antagonist atrasentan (5 mg·day−1·kg−1 body weight) or vehicle. DOCA-salt mice displayed increased systolic blood pressure (SBP), and treatment with atrasentan decreased SBP in DOCA-salt mice. Contractile responses in cavernosal strips from DOCA-salt mice were enhanced by ET-1, phenylephrine, and electrical field stimulation (EFS) of adrenergic nerves, whereas relaxations were not altered by IRL-1620 (an ETB agonist), acetylcholine, sodium nitroprusside, and EFS of nonadrenergic noncholinergic nerves. PD59089 (an ERK1/2 inhibitor), but not Y-27632 (a Rho-kinase inhibitor), abolished enhanced contractions to ET-1 in cavernosum from DOCA-salt mice. Treatment of DOCA-salt mice with atrasentan did not normalize cavernosal responses. In summary, DOCA-salt treatment in mice enhances cavernosal reactivity to contractile, but not to relaxant, stimuli, via ET-1/ETA receptor-independent mechanisms.Item Activation of the ET-1/ETA pathway contributes to erectile dysfunction associated with mineralocorticoid hypertension.(2008) Carneiro, Fernando Silva; Nunes, Kenia Pedrosa; Vitorino, Fernanda Regina Casagrande Giachini; Lima, Victor Vitorino; Carneiro, Zidonia N.; Nogueira, Edson F.; Leite, Romulo; Ergul, Adviye; Rainey, William E.; Webb, Robert Clinton; Passaglia, Rita de Cassia Aleixo TostesIntroduction. The cavernosal tissue is highly responsive to endothelin-1 (ET-1), and penile smooth muscle cells not only respond to but also synthesize ET-1. Aim. Considering that ET-1 is directly involved in end-organ damage in salt-sensitive forms of hypertension, we hypothesized that activation of the ET-1/ETA receptor pathway contributes to erectile dysfunction (ED) associated with mineralocorticoid hypertension. Methods. Wistar rats were uninephrectomized and submitted to deoxycorticosterone acetate (DOCA)-salt treatment for 5 weeks. Control (Uni [uninephrectomized control]) animals were uninephrectomized and given tap water. Uni and DOCA-salt rats were simultaneously treated with vehicle or atrasentan (ETA receptor antagonist, 5 mg/ Kg/day). Cavernosal reactivity to ET-1, phenylephrine (PE), ETB receptor agonist (IRL-1620) and electric field stimulation (EFS) were evaluated in vitro. Expression of ROCKa, ROCKb, myosin phosphatase target subunit 1 (MYPT-1), and extracellular signal-regulated kinase 1/2 (ERK 1/2) were evaluated by western blot analysis. ET-1 and ETA receptor mRNA expression was evaluated by real-time reverse-transcriptase polymerase chain reaction. Voltage-dependent increase in intracavernosal pressure/mean arterial pressure (ICP/MAP) was used to evaluate erectile function in vivo. Main Outcome Measure. ETA receptor blockade prevents DOCA-salt-associated ED. Results. Cavernosal strips from DOCA-salt rats displayed augmented preproET-1 expression, increased contractile responses to ET-1 and decreased relaxation to IRL-1620. Contractile responses induced by EFS and PE were enhanced in cavernosal tissues from DOCA-salt hypertensive rats. These functional changes were associated with increased activation of the RhoA/Rho-kinase and ERK 1/2 pathways. Treatment of rats with atrasentan completely prevented changes in cavernosal reactivity in DOCA-salt rats and restored the decreased ICP/MAP, completely preventing ED in DOCA-salt rats. Conclusion. Activation of the ET-1/ETA pathway contributes to mineralocorticoid hypertension-associated ED. ETA receptor blockade may represent an alternative therapeutic approach for ED associated with salt-sensitive hypertension and in pathological conditions where increased levels of ET-1 are present.Item Cigarette smoking and erectile dysfunction : focus on NO bioavailability and ROS generation.(2008) Passaglia, Rita de Cassia Aleixo Tostes; Carneiro, Fernando Silva; Lee, Anthony; Vitorino, Fernanda Regina Casagrande Giachini; Leite, Romulo; Osawa, Yoichi; Webb, Robert ClintonIntroduction—Thirty million men in the United States suffer from erectile dysfunction (ED) and this number is expected to double by 2025. Considered a major public health problem, which seriously affects the quality of life of patients and their partners, ED becomes increasingly prevalent with age and chronic smoking is a major risk factor in the development of ED. Aim—To review available evidence concerning the effects of cigarette smoking on vascular changes associated with decreased nitric oxide (NO) bioavailability and increased reactive oxygen species (ROS) generation.Methods—We examined epidemiological and clinical data linking cigarette smoking and ED, and the effects of smoking on vascular NO bioavailability and ROS generation. Main Outcome Measures—There are strong parallels between smoking and ED and considerable evidence supporting the concept that smoking-related ED is associated with reduced bioavailability of NO because of increased ROS. Results—Cigarette smoking-induced ED in human and animal models is associated with impaired arterial flow to the penis or acute vasospasm of the penile arteries. Long-term smoking produces detrimental effects on the vascular endothelium and peripheral nerves and also causes ultrastructural damage to the corporal tissue, all considered to play a role in chronic smokinginduced ED. Clinical and basic science studies provide strong indirect evidence that smoking may affect penile erection by the impairment of endothelium-dependent smooth muscle relaxation or more specifically by affecting NO production via increased ROS generation. Whether nicotine or other products of cigarette smoke mediate all effects related to vascular damage is still unknown. Conclusions—Smoking prevention represents an important approach for reducing the risk of ED. The characterization of the components of cigarette smoke leading to ED and the mechanisms by which these components alter signaling pathways activated in erectile responses are necessary for a complete comprehension of cigarette smoking-associated ED.Item Adenosine actions are preserved in corpus cavernosum from obese and type II diabetic db/db mouse.(2008) Carneiro, Fernando Silva; Vitorino, Fernanda Regina Casagrande Giachini; Lima, Victor Vitorino; Neotzold, Zidonia Nunes; Leite, Romulo; Inscho, Edward W.; Passaglia, Rita de Cassia Aleixo Tostes; Webb, Robert ClintonIntroduction—Erectile dysfunction (ED) in diabetes is associated with autonomic neuropathy and endothelial dysfunction. Whereas the nonadrenergic-noncholinergic (NANC)/neurogenic nitric oxide pathway has received great attention in diabetes-associated ED, few studies have addressed sympathetic overactivity. Aim—To test the hypothesis that adenosine-induced inhibition of adrenergic-mediated contractile responses in mouse corpus cavernosum is impaired in the presence of diabetes. Methods—The db/db (obesity and type II diabetes caused by a leptin receptor mutation) mouse strain was used as a model of obesity and type II diabetes, and standard procedures were performed to evaluate functional cavernosal responses. Main Outcome Measures—Increased cavernosal responses to sympathetic stimulation in db/ db mice are not associated with impaired prejunctional actions of adenosine. Results—Electrical field stimulation (EFS)-, but not phenylephrine (PE)-, induced contractions are enhanced in cavernosal strips from db/db mice in comparison with those from lean littermates. Direct effects of adenosine, 2-chloro-adenosine, A1 receptor agonist C-8031 (N6 cyclopentyladenosine), and sodium nitroprusside are similar between the strips from lean and db/ db mice, whereas relaxant responses to acetylcholine and NANC stimulation are significantly impaired in the cavernosal strips from db/db mice. 5′-Iodotubercidin (adenosine kinase inhibitor) and dipyridamole (inhibitor of adenosine transport), as well as the A1 agonist C-8031, significantly and similarly inhibit contractions induced by stimulation of adrenergic nerves in the cavernosal strips from lean and db/db mice. Conclusions—Results from this study suggest that corpora cavernosa from obese and diabetic db/db mice display altered neural-mediated responses that would favor penile detumescence, i.e., increased contractile response to adrenergic nerve stimulation and decreased relaxant responses upon activation of NANC nerves. However, increased cavernosal responses to adrenergic nerve stimulation are not due to impaired negative modulation of sympathetic neurotransmission by adenosine in this diabetic model.Item Erectile function in two-kidney, one-clip hypertensive rats is maintained by a potential increase in nitric oxide production.(2009) Linder, Elizabeth; Dorrance, Anne M.; Mills, Thomas M.; Webb, Robert Clinton; Leite, RomuloIntroduction - Hypertension is closely associated with erectile dysfunction (ED) as it has been observed in many experimental models of hypertension. Additionally, epidemiological studies show that approximately a third of the hypertensive patients have ED. Aim—To test the hypothesis that the two-kidney one-clip (2K-1C) rat model of hypertension displays normal erectile function due to increased nitric oxide (NO) production in the penis. Methods—Ganglionic-induced increase in intracavernosal pressure (ICP)/mean arterial pressure (MAP) ratio was used as an index of erectile function in 2K-1C and in normotensive shamoperated (SHAM) anesthetized rats. Cavernosal strips from hypertensive and normotensive rats were used for isometric tension measurement. The contraction induced by alpha-adrenergic agonist phenylephrine, and the relaxation induced by the nitric oxide (NO) donor sodium nitroprusside (SNP) and by the Rho-kinase inhibitor Y-27632 were performed in the absence and in the presence of the nitric oxide synthase (NOS) inhibitor L-NNA. Results—Changes in ICP/MAP induced by ganglionic stimulation were not different between 2K-1C and SHAM rats. The contractile response induced by phenylephrine as well as the relaxation induced by SNP or the Y-27632 were similar in cavernosal strips from both groups. However, in the presence of L-NNA, the relaxation induced by Y-27632 was significantly impaired in 2K-1C compared to SHAM). Conclusions—These data suggest that hypertension and ED could be dissociated from high levels of blood pressure in some animal models of hypertension. Erectile function in 2K-1C hypertensive rats is maintained in spite of the increased Rho-kinase activity by increased NO signaling.Item Nitric oxide-induced vasorelaxation in response to PnTx2-6 toxin from Phoneutria nigriventer spider in rat cavernosal tissue.(2010) Nunes, Kenia Pedrosa; Cordeiro, Marta do Nascimento; Richardson, Michael; Borges, Marcia Helena; Diniz, Simone Odília Antunes Fernandes; Cardoso, Valbert Nascimento; Passaglia, Rita de Cassia Aleixo Tostes; Garcia, Maria Elena de Lima Perez; Webb, Robert Clinton; Leite, RomuloIntroduction—Priapism is one of several symptoms observed in accidental bites by the spider Phoneutria nigriventer. The venom of this spider is comprised of many toxins, and the majority has been shown to affect excitable ion channels, mainly sodium (Na+) channels. It has been demonstrated that PnTx2-6, a peptide extracted from the venom of P. nigriventer, causes erection in anesthetized rats and mice. Aim—We investigated the mechanism by which PnTx2-6 evokes relaxation in rat corpus cavernosum. Main Outcome Measures—PnTx2-6 toxin potentiates nitric oxide (NO)-dependent cavernosal relaxation.Item Increased cavernosal relaxation by Phoneutria nigriventer toxin, PnTx2-6, via activation at NO/cGMP signaling.(2011) Nunes, Kenia Pedrosa; Wynne, B. M.; Cordeiro, Marta do Nascimento; Borges, Marcia Helena; Richardson, Michael; Leite, Romulo; Garcia, Maria Elena de Lima Perez; Webb, Robert ClintonErectile dysfunction mechanisms in diabetic patients are multifactorial and often lead to resistance to current therapy. Animal toxins have been used as pharmacological tools to study penile erection. Human accidents involving the venom of Phoneutria nigriventer spider are characterized by priapism. We hypothesize that PnTx2-6 potentiates cavernosal relaxation in diabetic mice by increasing cGMP. This effect is nNOS dependent. Cavernosal strips were contracted with phenylephrine (10−5 M) and relaxed by electrical field stimulation (EFS, 20V, 1–32 Hz) in the presence or absence of PnTx2-6 (10−8 M).Cavernosal strips from nNOS and eNOS knocaut (KO) mice, besides nNOS inhibitor (10−5M), were used to evaluate the role of this enzyme in the potentiation effect evoked by PnTx2-6. Tissue cGMP levels were determined after stimulation with PnTx2-6 in presence or absence of L-NAME (10−4M) and ω-conotoxin GVIA (10−6M), an N-type calcium channel inhibitor. Results showed PnTx2-6 enhanced cavernosal relaxation in diabetic mice (65%) and eNOS KO mice, but not in nNOS KO mice. The toxin effect in the cavernosal relaxation was abolished by nNOS inhibitor. cGMP levels are increased by PnTx2-6, however L-NAME abolished this enhancement as well as ω-conotoxin GVIA. We conclude PnTx2-6 facilitates penile relaxation in diabetic mice through a mechanism dependent on nNOS, probably via increasing NO/cGMP production.Item Anti-Platelet therapy with clopidogrel prevents endothelial dysfunction and vascular remodeling in aortas from hypertensive rats.(2014) Vitorino, Fernanda Regina Casagrande Giachini; Leite, Romulo; Osmond, David A.; Lima, Victor Vitorino; Inscho, Edward W.; Webb, Robert Clinton; Passaglia, Rita de Cassia Aleixo TostesThe aim was to investigate the beneficial effects of clopidogrel in thoracic aorta function and structure and to characterize if P2Y12 receptors contribute to these effects. Male Sprague Dawley rats were infused with angiotensin II [(Ang II) 60 ng.min21, 14 days] or saline (control rats) and were simultaneously treated with clopidogrel (10 mg.kg21.day21) or vehicle. After 14 days, systolic blood pressure (mmHg) was similar in Ang II-hypertensive rats treated with clopidogrel or vehicle (19969 vs. 190611, respectively). Systolic blood pressure in control rats was not altered by clopidogrel treatment (12861 vs. vehicle, 13462). Endothelium-dependent relaxation induced by 2-MeS-ADP was decreased in aortas from vehicle-treated Ang II-hypertensive rats, compared to vehicle-treated control rats. This response was elicited via activation of P2Y1 and P2Y12 receptors. In the presence of L-NAME and indomethacin, 2-MeS-ADP induced contraction and this response was augmented in vehicle-treated Ang II-hypertensive rats, compared to vehicle-treated control rats. The contraction to 2-MeS-ADP was evoked by P2Y13 and P2Y12 receptor activation. Clopidogrel-treatment did not normalize relaxation or contractile responses induced by 2-MeS-ADP in aortas from Ang II-hypertensive rats. P2Y1 and P2Y12 protein expression was increased, whereas P2Y13 receptor expression was reduced in aorta from vehicle-treated Ang II-hypertensive rats. Endothelium-dependent relaxation upon acetylcholine-stimulation was reduced in vehicle-treated Ang II-hypertensive rats, and clopidogrel treatment was effective in improving endothelial function. Clopidogrel also prevented vascular remodeling, evidenced by augmented media thickness in aortas from Ang II-hypertensive rats. Clopidogrel has beneficial effects on the aortic endothelium of Ang II-hypertensive rats, but its effects do not seem to be directly related to the presence of P2Y12 receptors in this vessel.Item Comparison of the involvement of protein kinase C in agonist-induced contractions in mouse aorta and corpus cavernosum.(2008) Jin, Liming; Teixeira, Cleber E.; Webb, Robert Clinton; Leite, RomuloProtein kinase C (PKC) is involved in the regulation of vascular smooth muscle contraction. However, the role of PKC in erectile function is poorly understood. This study investigated whether PKC mediates agonistinduced contractions in mouse penile tissue (corpora cavernosa). We also compared the effects of PKC activators and inhibitors on contractile responses in mouse corpus cavernosum with those in mouse aorta. Aortic rings and corpus cavernosal strips from C57BL/6J mice were mounted in the organ bath for isometric tension recording. Our data showed that a PKCα/β selective inhibitor, Gö6976 (10 μM), inhibited phenylephrine and 9,11-dideoxy-11α,9α-epoxymethanoprostaglandin F2α (U46619, a thromboxane mimetic)- induced contractions in mouse aorta, reducing the maximum contraction by 94% and 17%, respectively. A non-selective PKC inhibitor, chelerythrine (30 μM), also significantly reduced phenylephrineand U46619-induced maximum contractions in mouse aorta. However, Gö6976 and chelerythrine had no significant effects on phenylephrine- and U46619-induced contractions in corpus cavernosum. Furthermore, a PKC activator, phorbol-12,13-dibutyrate (0.1 μM), significantly increased contractions in aorta (208±14% of KCl-induced maximum contraction) but failed to cause contractions in corpus cavernosum at 1 and 10 μM. Western blot analysis data suggested that protein expression of PKC was similar in aorta and corpus cavernosum. Taken together, our data indicate that PKC does not have a significant role in agonist-induced contractions in mouse corpus cavernosum, whereas it mediates the contractile response to agonists in the aorta.Item Tx2-6 toxin of the Phoneutria nigriventer spider potentiates rat erectile function.(2008) Nunes, Kenia Pedrosa; Gonçalves, Andrey Christian da Costa; Lanza, Luciana Franco; Côrtes, Steyner de França; Cordeiro, Marta do Nascimento; Michael, Richardson; Pimenta, Adriano Monteiro de Castro; Webb, Robert Clinton; Garcia, Maria Elena de Lima PerezThe venom of the spider Phoneutria nigriventer contains several toxins that have bioactivity in mammals and insects. Accidents involving humans are characterized by various symptoms including penile erection. Here we investigated the action of Tx2-6, a toxin purified from the P. nigriventer spider venom that causes priapism in rats and mice. Erectile function was evaluated through changes in intracavernosal pressure/mean arterial pressure ratio (ICP/MAP) during electrical stimulation of the major pelvic ganglion (MPG) of normotensive and deoxycorticosterone-acetate (DOCA)-salt hypertensive rats. Nitric oxide (NO) release was detected in cavernosum slices with fluorescent dye (DAF-FM) and confocal microscopy. The effect of Tx2-6 was also characterized after intracavernosal injection of a non-selective nitric oxide synthase (NOS) inhibitor, L-NAME. Subcutaneous or intravenous injection of Tx2-6 potentiated the elevation of ICP/MAP induced by ganglionic stimulation. L-NAME inhibited penile erection and treatment with Tx2-6 was unable to reverse this inhibition. Tx2-6 treatment induced a significant increase of NO release in cavernosum tissue. Attenuated erectile function of DOCA-salt hypertensive rats was fully restored after toxin injection. Tx2-6 enhanced erectile function in normotensive and DOCA-salt hypertensive rats, via the NO pathway. Our studies suggest that Tx2-6 could be important for development of new pharmacological agents for treatment of erectile dysfunction.