Effects of estrogen on the vascular system

The cardiovascular protective actions of estrogen are partially mediated by a direct effect on the vessel wall. Estrogen is active both on vascular smooth muscle and endothelial cells where functionally competent estrogen receptors have been identified. Estrogen administration promotes vasodilation in humans and in experimental animals, in part by stimulating prostacyclin and nitric oxide synthesis, as well as by decreasing the production of vasoconstrictor agents such as cyclooxygenase-derived products, reactive oxygen species, angiotensin II, and endothelin-1. In vitro, estrogen exerts a direct inhibitory effect on smooth muscle by activating potassium efflux and by inhibiting calcium influx. In addition, estrogen inhibits vascular smooth muscle cell proliferation. In vivo, 17ß-estradiol prevents neointimal thickening after balloon injury and also ameliorates the lesions occurring in atherosclerotic conditions. As is the case for other steroids, the effect of estrogen on the vessel wall has a rapid non-genomic component involving membrane phenomena, such as alteration of membrane ionic permeability and activation of membrane-bound enzymes, as well as the classical genomic effect involving estrogen receptor activation and gene expression

Gender differences in vascular expression of endothelin and ET A/ET B receptors, but not in calcium handling mechanisms, in deoxycorticosterone acetate-salt hypertension

We determined if the increased vascular responsiveness to endothelin-1 (ET-1) observed in male, but not in female, DOCA-salt rats is associated with differential vascular mRNA expression of ET-1 and/or ET A/ET B receptors or with functional differences in Ca2+ handling mechanisms by vascular myocytes. Uninephrectomized male and female Wistar rats received DOCA and drinking water containing NaCl/KCl. Control rats received vehicle and tap water. Blood pressure and contractile responses of endothelium-denuded aortic rings to agents which induce Ca2+ influx and/or its release from internal stores were measured using standard procedures. Expression of mRNA for ET-1 and ET A/ET B receptors was evaluated by RT-PCR after isolation of total cell RNA from both aorta and mesenteric arteries. Systolic blood pressure was higher in male than in female DOCA rats. Contractions induced by Bay K8644 (which activates Ca2+ influx through voltage-operated L-type channels), and by caffeine, serotonin or ET-1 in Ca2+-free buffer (which reflect Ca2+ release from internal stores) were significantly increased in aortas from male and female DOCA-salt compared to control aortas. DOCA-salt treatment of male, but not female, rats statistically increased vascular mRNA expression of ET-1 and ET B receptors, but decreased the expression of ET A receptors. Molecular up-regulation of vascular ET B receptors, rather than differential changes in smooth muscle Ca2+ handling mechanisms, seems to account for the increased vascular reactivity to ET-1/ET B receptor agonists and higher blood pressure levels observed in male DOCA-salt rats

The role of endothelium in vascular reactivity

1. This review desribes the role of vascular endothelium in the response induced by different vasoactive agentes. 2. The interaction between endothelium, vascular smooth muscle and platelets is discussed. 3. The hormone control as well as pmhysicochemical alterations that interfere with some endothelium-dependent vascular responses are described

Reactivity of macro-and microvessels of doca-salt hypertensive rats: role of the endothelial cell

The responses to noradrenaline (NA) and acetylcholine (ACh) of aortae and microvessels were cocmpared in control and DOCA-salt hypertensive rats. Macro - and microvessels from hypertensive rats showed an increased response to NA and a decreased response to ACh (an endothelium-dependent vasodilator). Unlike ACh, sodium nitroprusside (an endothelium-independent agent), was equally effective in evoking a vasodilator response from aortae and microvessels of hypertensive rats. These data suggest that the impaired response to ACh and the increased response to NA in DOCA-salt hypertension may result from an alteration of endothelial cell function

Bioequivalência de formulaçöes farmacêuticas de bupivacaína: estudo sobre o marcapasso cardíaco / Bioequivalence of pharmaceutical formulations of bupivacaine: study on the artificial pacemaker

Estudou-se o efeito cardiodepressor, em marcapasso atrial de rato, do cloridrato de bupivacaína, comercializado no Brasil por diferentes laboratórios. A análise das curvas dose-resposta mostrou que a resposta depressora é dose-dependente sobre o cronotropismo atrial. Evidenciou-se, ainda, que o fármaco comercializado pela Abbott do Brasil apresentou ligeiro desvio à direita embora estatisticamente näo significante, sugerindo provável interferência do NaCI presente em sua formulaçäo. O metilparabeno, empregado como conservante pelos Laboratórios Lepetit S.A., näo interferiu na atividade depressora nem na vida média do produto, mostrando-se ainda equivalente, em todos os ponto da curva, ao medicamento fabricado pela Apsen do Brasil. O ensaio evidenciou que as amostras säo bioequivalentes de acordo com a metodologia de estudo, näo sendo encontradas diferenças estatisticamente significantes nos resultados obtidos. Pequenas diferenças observadas, sem significado estatístico, podem ser atribuídas às diferenças de formulaçäo, como por exemplo a presença do NaCI em um dos produtos

Interaçäo anestésicos locais e agentes bloqueadores de entrada de cálcio em átrios direito e esquerdo de cobaia / Local anesthetics and calcium channel blockers interactions in right and left atria of guinea pigs

Foi estudada "in vitro" a interaçäo entre anestésicos locais (bupivacaína e lidocaína) e bloqueadores de entrada de cálcio (verapamil) quanto ao cronotropismo e ao inotropismo cardíacos. A preparaçäo utilizada foi a de átrios direito e esquerdo de cobaia. Os resultados mostraram que o verapamil potencializa, nas condiçöes deste estudo, o efeito cronotrópico negativo tanto da lidocaína como da bupivacaína sobre o coraçäo. Por outro lado, o verapamil potencializava o efeito inotrópico negativo da lidocaína mas näo o da bupivacaína sobre o coraçäo. É discutido o possível mecanismo da interaçäo

Cardiotoxicidade da bupivacaína comparada a lidocaína: tempo de reversäo da parada atrial / Bupivacaine compared to lidocaine cardiotoxicity: recovery time of the atrial arrest

Foi investigada a potência relativa da bupivacaína comparada à lidocaína no cronotropismo e inotropismo atriais. Curvas concentraçäo-efeito cumulativas (CCE) foram realizadas e estabelecidas as CE50 (concentraçä0 eficaz 50%). Foi ainda investigado o tempo necessário para a reversäo das paradas atriais. Com base nos resultados obtidos pode-se concluir: a) a bupivacaína é mais cardiotóxica que a lidocaína; b) o tempo de reversäo das paradas atriais é quatro vezes maior para a bupivacaína do que para a lidocaína; c) os anestésicos locais estudados nos atrios direito e esquerdo reproduzem o mesmo comportamento que no nervo, quanto à potência e duraçäo de açäo

Consumo de psicofarmacos en cardiopatas (investigacion epidemiologica). / Consumption of psychotropic drugs by cardiac patients (epidemiological research)

Se analizan 164 historias clinicas de enfermos cardiopatas que acudieron a Consultorio Externo de Cardiologia entre los anos 1978 y 1980. Se observo que el 66,46% de estos pacientes consumen psicofarmacos con un predominio significativo del sexo femminino. Dentro de este mismo grupo predominan los consumidores sobre los no consumidores de psicofarmacos; en cambio, en el sexo masculino, dicha diferencia no fue significativa.No dubo diferencias significativas en las edades de ambos grupos. Se consumieron prodominantemente ansioliticos. Se observo primacia feminina en cada tipo de droga estudiada. En la mayoria de los enfermos la ingesta fue permanente, nuevamente con predominio feminino. No se hallo diferencias entre ambos sexos cuando la ingesta fue no permanente. La mayoria de los estudiosos reciberon psicofarmacos por indicacion medica con predominio feminino.En cambio, en la minoria que se automedica, no se encontraron diferencias entre ambos sexos