RESUMO
Our experiments were designed to determine the acute effects of 17beta-estradiol on femoral veins from intact and ovariectomized female pigs. Rings of femoral veins with or without endothelium were suspended in organ chambers for measurement of isometric force. Concentration-response curves to 17beta-estradiol (10(-9) to 10(-5) M) were obtained in veins contracted with prostaglandin F(2alpha) in the absence and presence of inhibitors of either estrogen receptors (ICI-182780; 10(-5) M), nitric oxide synthase [N(G)-monomethyl-l-arginine (l-NMMA); 10(-4) M], soluble guanylate cyclase (1-H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one; 10(-5) M), or potassium channels (tetraethylammonium; 10(-2) M). Estrogen receptors were identified with the use of Western blotting and immunostaining in veins of both groups. 17beta-Estradiol caused acute endothelium-dependent relaxations in both groups. Relaxations to 17beta-estradiol were inhibited by l-NMMA and 1-H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one but not ICI-182780. Tetraethylammonium inhibited relaxations only in veins with endothelium from intact females. Results indicate that 17beta-estradiol causes acute endothelium-dependent relaxations in femoral veins. The relative contribution of nitric oxide and K(+) channels as mechanisms involved in relaxations to 17beta-estradiol in femoral veins is modulated by ovarian status.
Assuntos
Estradiol/análogos & derivados , Estradiol/farmacologia , Veia Femoral/efeitos dos fármacos , Veia Femoral/fisiologia , Animais , Dinoprosta/farmacologia , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Feminino , Veia Femoral/citologia , Fulvestranto , Imuno-Histoquímica , Técnicas In Vitro , Ovariectomia , Bloqueadores dos Canais de Potássio/farmacologia , Receptores de Estrogênio/antagonistas & inibidores , Estereoisomerismo , Suínos , Vasoconstrição/efeitos dos fármacos , Vasoconstrição/fisiologia , Vasodilatação/efeitos dos fármacos , Vasodilatação/fisiologiaRESUMO
Experiments were designed to determine how ovariectomy modulates mitogenic factors in platelets and how these factors affect proliferation of coronary arterial smooth muscle. Platelet-derived growth factors (PDGF(AB) and PDGF(BB)), transforming growth factors (TGF-beta(1) and TGF-beta(2)), and vascular endothelial growth factor (VEGF(165)) were quantified in platelet lysates and platelet-poor plasma from adult gonadally intact and ovariectomized female pigs by ELISA. Proliferation of cultured coronary arterial smooth muscle cells (SMCs) from both groups of pigs was determined in response to autologous or heterologous platelet lysates. Platelet concentrations of PDGF(BB), but not PDGF(AB), TGF-beta(1), and TGF-beta(2), increased with ovariectomy. VEGF(165) was not detected in platelets from either group. Proliferation of SMCs from ovariectomized females was significantly greater on exposure to autologous or heterologous platelet lysates than proliferation of SMCs from intact females. These results indicate that ovariectomy increases concentrations of PDGF(BB) in platelets. Higher levels of PDGF(BB) in platelets in synergy with other platelet-derived products could contribute to increased proliferative arterial response to injury after ovariectomy.
Assuntos
Plaquetas/fisiologia , Mitógenos/metabolismo , Músculo Liso Vascular/citologia , Ovariectomia , Animais , Biópsia , Plaquetas/química , Células da Medula Óssea/citologia , Divisão Celular/fisiologia , Vasos Coronários/citologia , Feminino , Imunofluorescência , Megacariócitos/citologia , Músculo Liso Vascular/metabolismo , Contagem de Plaquetas , Fator de Crescimento Derivado de Plaquetas/metabolismo , Receptores de Estrogênio/análise , Suínos , Fator de Crescimento Transformador beta/metabolismo , Fator de Crescimento Transformador beta1 , Fator de Crescimento Transformador beta2RESUMO
Nicotine patches are available as an over-the-counter medication for aid in smoking cessation. This study was designed to determine how nicotine patch therapy over time and dose ranges used in smoking cessation programs in humans affects endothelium-dependent relaxations. Dogs were treated with nicotine patches (11, 22, or 44 mg/day) for 2 and 5 wk. Circulating nicotine and oxidized products of nitric oxide (NOx) were measured. Coronary arteries were prepared for measurement of isometric force and aortic endothelial cells were prepared for measurement of mRNA or NO synthase (NOS) activity. Circulating nicotine increased with increasing concentrations of nicotine patches. After 5 wk of treatment with 22 mg/day patches, circulating NOx was reduced but NOS activity was increased. NOS mRNA was similar among groups. Only after 5 wk of treatment with 22 mg/day patches were endothelium-dependent relaxations reduced to alpha(2)-adrenergic agonists, ADP, and the calcium ionophore A-23187. These results suggest a time and biphasic dose effect of nicotine treatment on endothelium-dependent responses that may be related to bioavailability of NO. This complex relationship of duration and dose of nicotine treatment may explain, in part, discrepancies in effects of nicotine on endothelium-dependent responses.
Assuntos
Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/fisiologia , Nicotina/administração & dosagem , Difosfato de Adenosina/farmacologia , Administração Cutânea , Animais , Aorta/enzimologia , Calcimicina/farmacologia , Cálcio/fisiologia , Vasos Coronários/efeitos dos fármacos , Vasos Coronários/fisiologia , Cotinina/sangue , Cães , Relação Dose-Resposta a Droga , Endotélio Vascular/enzimologia , Inibidores Enzimáticos/farmacologia , Técnicas In Vitro , Ionóforos/farmacologia , Masculino , Nicotina/sangue , Nicotina/farmacologia , Nitratos/sangue , Óxido Nítrico Sintase/metabolismo , Nitritos/sangue , RNA Mensageiro/metabolismo , Fatores de Tempo , Vasodilatação/efeitos dos fármacos , ômega-N-Metilarginina/farmacologiaRESUMO
Experiments were designed to determine the effects of nicotine treatment on the functions of saphenous veins used for coronary artery bypass grafts in dogs. Dogs received either no treatment or transdermal nicotine for 5 weeks at doses of 11 mg, 22 mg or 44 mg/day. Saphenous veins were removed and suspended for the measurement of isometric force in organ chambers. Endothelium was removed mechanically from some rings. N(G)-mono-methyl-L-arginine (L-NMMA; 10(-4) M) was used to inhibit the production of nitric oxide. Contractions to alpha2-adrenergic stimulation were decreased in veins from dogs treated with a 22-mg/day dose of transdermal nicotine. In addition, endothelium-dependent relaxations to adenosine-diphosphate (10(-8)-10(-4) M) and the calcium ionophore A23,187 (10(-8)-10(-6) M) were decreased in veins from dogs with a 22-mg/day dose and increased in veins from dogs treated with a 44-mg/day dose. These relaxations were inhibited by L-NMMA. Plasma concentrations of oxidized products of nitric oxide were decreased only in dogs treated with 22 mg/day of nicotine. The relaxation of rings without endothelium (direct response on the smooth muscle) to nitric oxide were not altered by nicotine treatment. These results suggest that the short-term treatment of dogs with intermediate (22 mg/day) but not low (11 mg/day) or high (44 mg/day) doses of transdermal nicotine decreases the endothelial function of veins used for coronary artery bypass grafts. Therefore, changes in plasma products of nitric oxide and endothelium-dependent relaxations mediated by nitric oxide are related to the dose of nicotine treatment.
Assuntos
Contração Isométrica/efeitos dos fármacos , Músculo Liso Vascular/fisiologia , Nicotina/farmacologia , Veia Safena/fisiologia , Administração Cutânea , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Tartarato de Brimonidina , Calcimicina/farmacologia , Cães , Relação Dose-Resposta a Droga , Endotélio Vascular/fisiologia , Técnicas In Vitro , Masculino , Relaxamento Muscular/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Nicotina/administração & dosagem , Nicotina/sangue , Óxido Nítrico/sangue , Cloreto de Potássio/farmacologia , Quinoxalinas/farmacologia , Veia Safena/efeitos dos fármacos , ômega-N-Metilarginina/farmacologiaRESUMO
BACKGROUND: Experiments were to characterize pharmacologically adrenergic receptors in human varicose veins to the natural transmitter norepinephrine and to an extract of Ruscus. METHODS: Greater saphenous veins and varicose tributaries from patients undergoing elective surgery for primary varicose disease and portions of greater saphenous veins from patients undergoing peripheral arterial reconstruction (control) were suspended for the measurement of isometric force in organ chambers. Concentration response curves were obtained to norepinephrine or the extract of Ruscus aculeatus in the absence and presence of selective antagonists of alpha, and alpha2 adrenergic receptors. RESULTS: Norepinephrine and Ruscus extract caused concentration-dependent contractions in all veins. Contractions to norepinephrine were greater in control veins than in varicose tributaries. Contractions to the extract were greater in varicose tributaries than in greater saphenous veins from varicose patients. Contractions to norepinephrine were reduced similarly by alpha and alpha2-adrenergic agonists in control and varicose veins but to a greater extent by alpha2-blockade in greater saphenous veins from varicose patients. Contractions to Ruscus extract were not reduced by alpha-adrenergic blockade in control veins but were reduced by alpha2-adrenergic blockade in varicose veins. CONCLUSIONS: These results suggest a differential distribution of alpha adrenergic receptors on greater saphenous veins from non-varicose patients compared to those with primary varicose disease. Venotropic agents from plant extract probably exert effects by way of multiple receptor and non-receptor mediated events.
Assuntos
Receptores Adrenérgicos alfa/efeitos dos fármacos , Veia Safena/química , Varizes/metabolismo , Agonistas alfa-Adrenérgicos/farmacologia , Idoso , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Norepinefrina/farmacologia , Extratos Vegetais/farmacologia , Receptores Adrenérgicos alfa/análise , Varizes/cirurgia , Vasoconstrição/efeitos dos fármacosRESUMO
OBJECTIVE: Experiments were designed to determine the production of prostacyclin and thromboxane and the activation of cyclic nucleotides in human varicose and nonvaricose veins and to determine whether these second messenger pathways were differentially activated by the venotropic extract of Ruscus aculeatus. METHODS: The experiments were designed to characterize the activity of cyclic nucleotides and the production of prostaglandins in human varicose and nonvaricose veins. Segments of the greater saphenous veins and the adjacent tributaries were obtained from patients who underwent vein stripping and excision of primary varicose veins. The saphenous veins from the patients who underwent peripheral arterial bypass grafting were used as controls. The segments of veins were incubated in Krebs-Ringer bicarbonate solution in the presence of venotropic extract of Ruscus aculeatus (10(-3) g/mL) or in water-miscible organic solvent (dimethyl sulfoxide, 10(-3) g/mL), for 1, 5, and 10 minutes at 37 degrees C. The nonspecific phosphodiesterase inhibitor (3-isobutyl-1-methylxanthine, 10(-4) g/mL) was used to block cyclic nucleotide degradation in some samples. Tissue and media samples were collected. Tissue concentrations of both cyclic adenosine monophosphate and cyclic guanosine monophosphate (cAMP and cGMP, respectively) and media concentrations of 6-ketoprostaglandin-F(1)(alpha) (the stable metabolite of prostacyclin) and thromboxane B(2) (the stable metabolite of thromboxane A(2)) were measured by means of radioimmunoassay. Cyclooxygenase 2 was measured with Western blot analysis. RESULTS: The varicose veins showed greater levels of cAMP but not of cGMP at all time points as compared with the control veins. Prostanoid production was not significantly altered in the varicose veins. Stimulation with Ruscus aculeatus increased the cAMP concentration in the varicose veins but did not affect the cGMP levels. The ratio between 6-ketoprostaglandin-F(1)(alpha) and thromboxane B(2) was two-fold greater in the varicose veins as compared with the control veins. In the presence of the extract, the ratio of 6-ketoprostaglandin-F(1)(alpha) and thromboxane B(2) was identical in both types of veins. Cyclooxygenase 2 was not present in either the control or the varicose veins. CONCLUSION: These results suggest that cAMP levels are elevated in varicose veins and that they can be altered with drug treatment in varicose veins. This chemical pathway may be considered as a modulatory target to affect contraction with venotropic drugs.
Assuntos
6-Cetoprostaglandina F1 alfa/biossíntese , AMP Cíclico/metabolismo , Tromboxano B2/biossíntese , Varizes/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , GMP Cíclico/metabolismo , Ciclo-Oxigenase 2 , Feminino , Humanos , Isoenzimas/biossíntese , Masculino , Proteínas de Membrana , Pessoa de Meia-Idade , Peroxidases/biossíntese , Prostaglandina-Endoperóxido Sintases/biossíntese , Veia Safena/metabolismo , Sistemas do Segundo MensageiroRESUMO
Nicotine may affect cardiovascular function through release of neurotransmitters from autonomic nerves or release of vasoactive substances from the vascular endothelium. Nitric oxide is a neurotransmitter and endothelium-derived factor that reduces tone of vascular smooth muscle. Experiments were designed to determine whether or not use of nicotine nasal spray for smoking cessation affects plasma levels of nitric oxide. Forty smokers self-administered nicotine by nasal spray (one 0.5 mg spray to each nostril). Blood samples were taken before the use of the nasal spray and at treatment day 7 for the measurement of cotinine by high pressure liquid chromatography and nitric oxide (NOx) by chemiluminescence. Age-comparable controls were never-smokers nonnicotine users recruited from laboratory personnel. Mean plasma concentrations of NOx from smokers before treatment were significantly greater compared with nonsmokers (23 +/- 10, n = 40 and 15 +/- 6, n = 13 nmoles/mL [mean +/- SD], respectively, P < 0.01). Plasma NOx in smokers was not significantly correlated with the average daily number of cigarettes smoked (r2 = 0.02, P > 0.05) but was positively and linearly correlated with plasma cotinine (r2 = 0.13, P < 0.02). In 32 self-reported abstinent smokers (confirmed by expired carbon monoxide < 9 ppm) using nicotine nasal spray, cotinine decreased by 64% from pretreatment levels of 284 +/- 103 to posttreatment levels of 90 +/- 58 ng/mL. Plasma NOx was unchanged and went from 23.0 +/- 10.1 at pretreatment to 21 +/- 12 nmoles/mL with nicotine treatment. These results suggest that nicotine-use, independent of cigarette smoking, affects plasma NOx.