RESUMO
We used transgenic mice constitutively over-expressing erythropoietin ("tg6" mice) and wild-type (wt) mice to investigate whether the high hematocrit (hct), consequence of Epo over-expression affected: (1) the normoxic ventilation (V (E)) and the acute hypoxic ventilatory response (HVR) and decline (HVD), (2) the increase in ventilation observed after chronic exposure to hypobaric hypoxia (430mmHg for 21 days), (3) the respiratory "blunting", and (4) the erythrocythemic response induced by chronic hypoxia exposure. V (E) was found to be similar in tg6 and wt mice in normoxia (FIO2=0.21). Post-acclimation V (E) was significantly elevated in every time point in wt mice at FIO2=0.10 when compared to pre-acclimation values. In contrast, tg6 mice exhibited a non-significant increase in V (E) throughout acute hypoxia exposure. Changes in V (E) are associated with adjustments in tidal volume (V(T)). HVR and HVD were independent of EE in tg6 and wt mice before chornic hypoxia exposure. HVR was significantly greater in wt than in tg6 mice after chronic hypoxia. After acclimation, HVD decreased in tg6 mice. Chronic hypoxia exposure caused hct to increase significantly in wt mice, while only a marginal increase occurred in the tg6 group. Although pre-existent EE does not appear to have an effect on HVR, the observation of alterations on V(T) suggests that it may contribute to time-dependent changes in ventilation and in the acute HVR during exposure to chronic hypoxia. In addition, our results suggest that EE may lead to an early "blunting" of the ventilatory response.
Assuntos
Aclimatação/fisiologia , Eritropoetina/metabolismo , Hipóxia/metabolismo , Policitemia/metabolismo , Ventilação Pulmonar/fisiologia , Aclimatação/genética , Animais , Eritropoetina/genética , Feminino , Hematócrito , Hemoglobinas/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Consumo de Oxigênio/fisiologia , Policitemia/genética , Volume de Ventilação Pulmonar/fisiologiaRESUMO
Avian embryos at high altitude do not benefit of the maternal protection against hypoxia as in mammals. Nevertheless, avian embryos are known to hatch successfully at altitudes between 4,000 and 6,500 m. This review considers some of the processes that bring about the outstanding modifications in the pressure differences between the environment and mitochondria of avian embryos in hypoxic environments. Among species, some maintain normal levels of oxygen consumption ( VO2) have a high oxygen carrying capacity, lower the air cell-arterial pressure difference ( PAO2 - PaO2 ) with a constant pH. Other species decrease VO2, increase only slightly the oxygen carrying capacity, have a higher PAO2 - PaO2 difference than sea-level embryos and lower the PCO2 and pH. High altitude embryos, and those exposed to hypoxia have an accelerated decline of erythrocyte ATP levels during development and an earlier stimulation of 2,3-BPG synthesis. A higher Bohr effect may ensure high tissue PO2 in the presence of the high-affinity hemoglobin. Independently of the strategy used, they serve together to promote suitable rates of development and successful hatching of high altitude birds in hypoxic environments.
Assuntos
Altitude , Aves/fisiologia , Embrião não Mamífero/fisiologia , Hipóxia/fisiopatologia , Oxigênio/metabolismo , Adaptação Fisiológica , Animais , Pressão Atmosférica , Aves/embriologia , Consumo de Oxigênio , Pressão Parcial , Alvéolos Pulmonares/embriologia , Alvéolos Pulmonares/fisiologia , Troca Gasosa Pulmonar/fisiologia , Respiração , Especificidade da EspécieRESUMO
The beneficial role of erythrocytosis for O2 transport has been questioned by evidence from bloodletting and hemodilution research as well as by studies suggesting the existence of an "optimal" hematocrit (Hct) or hemoglobin concentration ([Hb]) value. To assess to what extent erythrocytosis is beneficial in Andean men at high altitude, we examined and discussed optimal [Hb] using a mathematical approach by modeling the mixed (mean) venous Po2 (Pv(O2)) and arterial O2 content, considering for both the relation between [Hb] and arterial Po2. Relations of [Hb] to other physiological variables such as cardiac output and convective arterial O2 transport were also discussed, revealing the importance of Pv(O2) in this model. Our theoretical analysis suggests that increasing [Hb] allows increase and maintenance of Pv(O2) with only moderate declines in arterial Po2 as a consequence of moderate increases in altitude, reaching its maximum at the optimal [Hb] of 14.7 g/dl. Our analysis also shows that [Hb] corresponding to high arterial O2 content and O2 transport values is apparently not quite advantageous for improvement of oxygenation. Furthermore, chronic mountain sickness is discussed as an insightful example of the effects of excessive erythrocytosis at high altitude.
Assuntos
Altitude , Hemoglobinas/metabolismo , Modelos Biológicos , Adulto , Animais , Artérias , Transporte Biológico , Humanos , Masculino , Oxigênio/sangue , Pressão Parcial , Peru , Policitemia/fisiopatologia , VeiasRESUMO
Chronically hypoxic humans and some mammals have attenuated ventilatory responses, which have been associated with high dopamine level in carotid bodies. Alveolar hypoventilation and blunted ventilatory response have been recognized to be at the basis of Chronic Mountain Sickness by generating arterial hypoxemia and polycythemia. To investigate whether dopamine antagonism could decrease the hemoglobin concentration by stimulating resting ventilation (VE) and/or hypoxic ventilatory response, 18 chronically hypoxic rats (5 weeks, PB=433 Torr) were studied with and without domperidone treatment (a peripheral dopamine antagonist). Acute and prolonged treatment significantly increased poikilocapnic ventilatory response to hypoxia (RVE ml/min/kg=VE at 0.1 FI(O(2))-VE at 0.21 FI(O(2))), from 506+/-36 to 697+/-48; and from 394+/-37 to 660+/-81, respectively. In addition, Domperidone treatment decreased hemoglobin concentration from 21.6+/-0.29 to 18.9+/-0.19 (P<0.01) in rats chronically exposed to hypobaric hypoxia. Our study suggests that the stimulant effect of D(2)-R blockade on ventilatory response to hypoxia seems to compensate the low hypoxic peripheral chemosensitivity after chronic exposure and the latter in turn decrease hemoglobin concentration.
Assuntos
Domperidona/farmacologia , Antagonistas de Dopamina/farmacologia , Hipóxia/tratamento farmacológico , Policitemia/tratamento farmacológico , Ventilação Pulmonar/efeitos dos fármacos , Animais , Doença Crônica , Hemoglobinas/efeitos dos fármacos , Hipóxia/complicações , Hipóxia/fisiopatologia , Masculino , Policitemia/etiologia , Ratos , Ratos Sprague-Dawley , Fatores de TempoRESUMO
We measured the activities of Na(+)K(+) ATPase and of enzymes of the glycolytic pathway, Krebs cycle, and the respiratory chain in cerebral cortex of mice exposed to chronic hypoxia for three weeks and compared their values with those of sea level controls. There were no differences in Na(+)K(+) ATPase activity or in the activity of glycolytic enzymes. In the Krebs cycle, a 66% increase of succinate dehydrogenase activity was found due to a lower Km. In contrast, respiratory chain cytochrome oxidase activity was reduced by 12% in mice exposed to hypoxia. This suggested that the metabolic demand would be satisfied despite the respiratory chain depression (cytochrome oxidase), probably due to anaerobic energy production within the mitochondria (succinate dehydrogenase).
Assuntos
Córtex Cerebral/metabolismo , Metabolismo Energético/fisiologia , Hipóxia Encefálica/metabolismo , Animais , Doença Crônica , Ciclo do Ácido Cítrico , Transporte de Elétrons , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Masculino , Camundongos , Mitocôndrias/enzimologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Succinato Desidrogenase/metabolismoRESUMO
Prevalence of excessive erythrocytosis, the main sign of chronic mountain sickness (CMS), is greater in postmenopausal Andean women than in premenopausal women. It is uncertain whether this greater prevalence is related to the decline in female hormones and ventilatory function after the occurrence of the menopause. To study this, we compared the physiological variables involved in the physiopathology of CMS [end-tidal CO(2) (PET(CO(2)), Torr) and end-tidal O(2) (PET(O(2)), Torr), arterial oxygen saturation (Sa(O(2)), %), and Hb concentration (g/dl)] and progesterone and estradiol levels between postmenopausal and premenopausal women, both in the luteal and follicular phases. Women residing in Cerro de Pasco (n = 33; 4,300 m) aged 26--62 yr were studied. Postmenopausal women compared with premenopausal women in the luteal phase had lower PET(O(2)) (48 +/- 4 vs. 53 +/- 2 Torr, P = 0.005) and Sa(O(2)) levels (82 +/- 12 vs. 88 +/- 12%, P < 0.005) and higher PET(CO(2)) (34 +/- 2 vs. 29 +/- 3 Torr, P = 0.005) and Hb concentration (19 +/- 1 vs. 14 +/- 2 g/dl, P < 0.005). In addition, plasma progesterone was negatively correlated with PET(CO(2)) and positively correlated with PET(O(2)) and Sa(O(2)). No clear relationship was found among the cycle phases between estradiol and the variables studied. In conclusion, our results reveal that, before menopause, there is better oxygenation and lower Hb levels in women long residing at altitude, and this is associated with higher levels of progesterone in the luteal phase of the cycle.
Assuntos
Altitude , Estradiol/sangue , Fase Folicular/fisiologia , Hipóxia , Fase Luteal/fisiologia , Ovário/fisiologia , Pós-Menopausa/fisiologia , Pré-Menopausa/fisiologia , Progesterona/sangue , Adulto , Pressão Sanguínea , Dióxido de Carbono/sangue , Feminino , Frequência Cardíaca , Humanos , Indígenas Sul-Americanos , Pessoa de Meia-Idade , Oxigênio/sangue , PeruRESUMO
Blood oxygen affinity and red blood cell properties were measured in three subspecies of genus Bufo: Bufo spinulosus limensis, collected at sea level and at an average day temperature of 20 degrees C; Bufo spinulosus trifolium, from 3100 m, average day temperature of 15 degrees C; and Bufo spinulosus flavolineatus, from 4100 m, average day temperature of 10 degrees C. Electrophoresis of the hemoglobin showed the same component in each of the three subspecies. At 20 degrees C the blood oxygen affinities (P50) showed small differences between Bufo spinulosus limensis and Bufo spinulosus trifolium, whereas the value for Bufo spinulosus flavolineatus was markedly lower. At 10 degrees C, the ambient temperature of Bufo spinulosus flavolineatus, the P50 was extremely low compared with the other two subspecies at their corresponding ambient temperatures.
Assuntos
Adaptação Fisiológica , Altitude , Bufonidae/fisiologia , Hemoglobinas/metabolismo , Oxigênio/sangue , Animais , Bufonidae/metabolismo , Eletroforese , Eritrócitos/metabolismo , Hemoglobinas/fisiologia , Oxigênio/fisiologia , Especificidade da Espécie , TemperaturaRESUMO
There have been a number of reports describing the hematological indicators of Andean residents living at altitudes above 4,000 m, but several confounding factors have made the published results difficult to interpret. To clear up the effect of hypoxia on hemoglobin concentration (Hb, g/dL), hematocrit (Hct, %) and red blood cell concentration (RBC, cells/microL), this publication describes and analyzes these variables in children, men, and women from three large and homogeneous populations living at 4,355 m (n = 151), 4,660 m (n = 400), and 5,500 m (n = 273) in the Southern Peruvian Andes. Hb, Hct, and RBC increase with age in men (p < 0.001), as well as in women (p < 0.001) at the three altitudes of the study. In children (boys and girls) living at 5,500, Hb increases 11% when compared with children living at 4,355 m, and in adults, Hb increases 9.6% when comparing the same altitudes. The maximum percentage increase in Hb with age was 5.6% at 5,500 m, in men and 3.2% at 4,355 m, in women. The average percentage of difference for the Hb concentration between adult men and women is 6.6% at 4,355 m, 9.8% at 4,660 m, and 11.6% at 5,500 m. The differences in Hb concentration between men and women can only be seen after puberty. Finally, Hb is higher in older than younger women, which confirms the role of menopause in the development of erythremia. The result of this analysis reinforces the notion that Hb and Hct seem to be stable and useful parameters for acclimatization only at moderate altitudes; with aging or with increasing altitude, they may become excessive and lose their efficiency to protect the venous oxygen pressure.
Assuntos
Aclimatação/fisiologia , Altitude , Índices de Eritrócitos , Hematócrito , Hemoglobinas/análise , Policitemia/sangue , Características de Residência/estatística & dados numéricos , Adolescente , Adulto , Fatores Etários , Análise de Variância , Criança , Pré-Escolar , Fatores de Confusão Epidemiológicos , Feminino , Humanos , Lactente , Masculino , Menopausa/sangue , Pessoa de Meia-Idade , Peru , Policitemia/etiologia , Valores de Referência , Estudos de Amostragem , Caracteres Sexuais , Estatísticas não ParamétricasRESUMO
Red blood cell carbonic anhydrase (CA) activity has not been studied in high altitude natives. Because CA is an intraerythocytic enzyme and high altitude natives are polycythemic, it is important to know if the activity of CA per red cell volume is different from that of their sea level counterparts. Blood was collected from healthy subjects living in Lima (150m) and from twelve subjects from Cerro de Pasco (4330m), and hematocrit and carbonic anhydrase activity were measured. As expected, the high altitude natives had significantly higher hematocrits than the sea level controls (p = 0.0002). No difference in the CA activity per milliliter of red cells was found between the two populations. There was no correlation between the hematocrit and CA activity.
Assuntos
Altitude , Anidrases Carbônicas/sangue , Eritrócitos/enzimologia , Anidrases Carbônicas/metabolismo , Hematócrito , Humanos , Pessoa de Meia-IdadeRESUMO
Gray gulls, Larus modestus, nest 1500 m above sea level in northern Chile's Atacama Desert, one of the driest in the world. Their eggshell gas permeability, one third of that found in other Larus species, is an adaptation that reduces water loss, but at the expense of oxygen diffusion into the air cell with resultant hypoxia and reduced metabolic rate. This contrasts with characteristics found in birds nesting at very high altitudes where oxygen diffusion across the egg shell is maximized at the expense of water conservation. The oxygen consumption (MO2) of Larus modestus is 66% that of Larus argentatus; the oxygen conductance (GO2) is equivalent to 48% of that obtained in 5 other bird species. The oxygen partial pressure (PAO2) in the air chamber of Larus modestus (84 Torr) is lower than that of 10 other bird species whose average (PAO2) is 106 Torr. The CO2 partial pressure (PACO2) in the air chamber of Larus modestus is 68 Torr, a higher value than that found in 9 other bird species whose average (PACO2) is 39 Torr.
Assuntos
Adaptação Fisiológica/fisiologia , Charadriiformes , Casca de Ovo/metabolismo , Consumo de Oxigênio/fisiologia , Oxigênio/metabolismo , Água/metabolismo , Animais , Transporte Biológico/fisiologia , Chile , Clima Desértico , Difusão , PermeabilidadeRESUMO
Blood oxygen affinity and red blood cell properties were measured in three subspecies of genus Bufo: Bufo spinulosus limensis, collected at sea level and at an average day temperature of 20§C; Bufo spinulosus trifolium, from 3100 m, average day temperature of 15§C; and Bufo spinulosus flavolineatus, from 4100 m, average day temperature of 10§C. Electrophoresis of the hemoglobin showed the same component in each of the three subspecies. At 20§C the blood oxygen affinities (P50) showed small differences between Bufo spinulosus limensis and Bufo spinulosus trifolium, whereas the value for Bufo spinulosus flavolineatus was markedly lower. At 10§C, the ambient temperature of Bufo spinulosus flavolineatus, the P50 was extremely low compared with the other two subspecies at their corresponding ambient temperatures.
Assuntos
Animais , Adaptação Fisiológica , Altitude , Bufonidae/fisiologia , Hemoglobinas/metabolismo , Oxigênio/sangue , Bufonidae/metabolismo , Eletroforese , Eritrócitos/metabolismo , Hemoglobinas/fisiologia , Oxigênio/fisiologia , TemperaturaRESUMO
Gray gulls, Larus modestus, nest 1500 m above sea level in northern Chile's Atacama Desert, one of the driest in the world. Their eggshell gas permeability, one third of that found in other Larus species, is an adaptation that reduces water loss, but at the expense of oxygen diffusion into the air cell with resultant hypoxia and reduced metabolic rate. This contrasts with characteristics found in birds nesting at very high altitudes where oxygen diffusion across the egg shell is maximized at the expense of water conservation. The oxygen consumption (MO2) of Larus modestus is 66% that of Larus argentatus; the oxygen conductance (GO2) is equivalent to 48% of that obtained in 5 other bird species. The oxygen partial pressure (PAO2) in the air chamber of Larus modestus (84 Torr) is lower than that of 10 other bird species whose average (PAO2) is 106 Torr. The CO2 partial pressure (PACO2) in the air chamber of Larus modestus is 68 Torr, a higher value than that found in 9 other bird species whose average (PACO2) is 39 Torr.
Assuntos
Animais , Adaptação Fisiológica/fisiologia , Água/metabolismo , Charadriiformes , Casca de Ovo/metabolismo , Consumo de Oxigênio/fisiologia , Oxigênio/metabolismo , Chile , Clima Desértico , Difusão , Permeabilidade , Transporte Biológico/fisiologiaRESUMO
Red blood cell carbonic anhydrase (CA) activity has not been studied in high altitude natives. Because CA is an intraerythocytic enzyme and high altitude natives are polycythemic, it is important to know if the activity of CA per red cell volume is different from that of their sea level counterparts. Blood was collected from healthy subjects living in Lima (150m) and from twelve subjects from Cerro de Pasco (4330m), and hematocrit and carbonic anhydrase activity were measured. As expected, the high altitude natives had significantly higher hematocrits than the sea level controls (p = 0.0002). No difference in the CA activity per milliliter of red cells was found between the two populations. There was no correlation between the hematocrit and CA activity.
Assuntos
Humanos , Pessoa de Meia-Idade , Altitude , Anidrases Carbônicas/sangue , Eritrócitos , Eritrócitos/enzimologia , Anidrases Carbônicas/metabolismo , HematócritoRESUMO
HIV and AIDS issues deal directly with Human Rights and Public Health. Four basic principles have been acknowledged internationally in connection with HIV/AIDS: Autonomy, confidentiality, right to health and non-discrimination. According to these principles, it is not possible to adopt illegal or unethical measures toward HIV- infected persons. However, these may rarely be necessary in the case of prisoners, taking into account the possibilities of unpredictable behavior, violence and use of drugs, which are common in prisons. The World Health Organization as well as the United Nations have established the possibility of taking measures, different from those outside the jail, that may be illegal but necessary in order to protect the human rights of inmates, the general prison population and the security of the penitentiary system. Therefore coercive measures such as isolation may be imposed upon an inmate infected by HIV when he or she deliberately may try to infect others. This paper examines different types of situations dealing with HIV/AIDS in prison and reviews the international recommendations and the way the Costa Rican legal and penitentiary system have adopted them in accordance with its legal system and national prison characteristics.
Assuntos
Infecções por HIV , Direitos Humanos , Prisioneiros/legislação & jurisprudência , Prisões/legislação & jurisprudência , Síndrome da Imunodeficiência Adquirida , Costa Rica , HumanosRESUMO
High-altitude (HA) natives have blunted ventilatory sensitivities to hypoxia, and it is uncertain whether this blunting is reversible on migration to sea level (SL). To study this, the ventilatory sensitivities to hypoxia of HA natives residing near SL were compared with those of SL natives. Two studies were performed. In study A, 24 HA subjects who had lived above 3,000 m for an average of 14 yr and had been resident at SL for an average of 23 yr were compared with 23 SL controls. In study B, 25 HA subjects who had lived above 3,500 m for at least 20 yr and had been resident at SL for no more than 5 yr were compared with 25 SL controls. Hypoxic sensitivities were assessed by breathing seven progressively more hypoxic gas mixtures that contained progressively more CO2 in an attempt to maintain isocapnia throughout. The ventilatory sensitivities to hypoxia (l . min-1 . %-1 . m-2) did not differ significantly (by analysis of variance) between HA and SL natives in either study A (-0.51 +/- 0.25, mean +/- SD) or study B (-0.34 +/- 0. 15), but the ventilatory sensitivities did differ significantly between the two studies for reasons which are not entirely clear. We conclude that HA natives residing at SL, even if previously at HA for >20 yr, do not maintain the severely blunted hypoxic responses that have been reported in such individuals.
Assuntos
Aclimatação/fisiologia , Altitude , Hipóxia/fisiopatologia , Mecânica Respiratória/fisiologia , Adulto , Feminino , Humanos , Masculino , Consumo de Oxigênio/fisiologia , PeruRESUMO
The objective of this study was to investigate the role of menopause in the appearance of the physiopathological sequence that leads to chronic mountain sickness (CMS) in a high-altitude female population. The females studied are 30-54 yr old (n = 152) and have permanent residence in Cerro de Pasco (Pasco, Peru; 4,300 m). The sample was divided into postmenopausal and premenopausal groups for comparison. Blood oxygen saturation (SaO2), excessive erythrocytosis [EE, measured by the level of hematocrit (Het)], peak expiratory flow rates (PEFR), and a score that represents the main signs and symptoms of CMS (CMSscore) were measured. Postmenopausal women had higher Het (50.2 +/- 4.04 vs. 47.4 +/- 4.13%, P < 0.001), lower SaO2 (81.9 +/- 4.12 vs. 84.7 +/- 3.14%, P < 0.001) and PEFR values (489 +/- 101 vs. 534 +/- 90 l/min, P < 0.02), and slightly higher CMSscore (19.1 +/- 3.37 vs. 17.9 +/- 3.48, P < 0.06) than premenopausal women. The prevalence of women with EE (EE = Hct > 56%) was found to be 8.8%. Forty-five percent of the postmenopausal subjects presented a high CMSscore (> 21), whereas only 22% of the premenopausal subjects presented this high value (P < 0.02). We can therefore conclude that menopause may represent a contributing factor for the development of CMS.
Assuntos
Doença da Altitude/etiologia , Menopausa/fisiologia , Adulto , Distribuição por Idade , Envelhecimento/sangue , Doença da Altitude/epidemiologia , Doença da Altitude/fisiopatologia , Doença Crônica , Feminino , Hematócrito , Humanos , Pessoa de Meia-Idade , Oxigênio/sangue , Pico do Fluxo Expiratório , Policitemia/epidemiologia , Pré-Menopausa/fisiologia , PrevalênciaRESUMO
High altitude (HA; n = 5) chickens (Gallus gallus) with a high oxygen hemoglobin (Hb) affinity were transported from their birthplace (Puno, Perú 4,000 m) down sea level (Lima, Perú). The in vivo whole blood oxygen affinity (P50) and the eggshell permeability (P) were studied after several months living at sea level and in the first (F1) and second (F2) generations born at sea level. Our approach was to analyze changes in Hb affinity and eggshell permeability, considered as indicators of HA adaptation in birds. Our results show an increase of the P50 values (a decrease in Hb affinity) towards sea-level values. The results in P indicate that this variable increases towards sea level values in the F2 generation. We conclude that in the Andean chicken, a relative "newcomer" to high altitude (no more than 500 years), neither the Hb affinity for oxygen nor the eggshell permeability are invariable indicators of HA adaptation, in contrast with other native high altitude mammals and birds.
Assuntos
Aclimatação/fisiologia , Altitude , Galinhas/sangue , Galinhas/fisiologia , Óvulo/metabolismo , Oxigênio/sangue , Animais , Evolução Biológica , Feminino , Permeabilidade , Reprodução/fisiologia , Fatores de TempoRESUMO
Se estudió 70 ratones Swiss macho de 3-4 meses de edad, para evaluar los efectos profilácticos y terapéuticos del analapril y la pentoxifilina en la policitemia inducida por hipoxia. Se dividió a los animales en dos grupos: grupo pentoxifilina (n=39) y grupo enalapril (n=31). Cada uno fue adicionalmente dividido en un grupo profiláctico que recibió el medicamento antes de la exposición a hipoxia hipobárica intermitente (IHH) y en un grupo terapéutico que recibió el medicamento luego de la exposición a IHH. Cada Subgrupo tuvo su respectivo control. La exposición a IHH fue realizada a través de una cámara hipobárica que simulaba una altura equivalente a 4500m, 22 horas por día. Se midió semanalmente peso y hematocrito. La evolución del peso corporal en el tiempo no mostró diferencias sustanciales entre los animales tratados y los controles en los grupos profilácticos y terapéuticos, tanto en los grupos pentoxifilina como enalapril. Hubo una disminución significativa del hematocrito a los 36 y 47 días del inicio de la profilaxis en el grupo pentoxifilina. En el grupo profiláctico enapril los hematocritos fueron significativamente menores en los animales tratados. Concluimos que ambas drogas son efectivas cuando son usadas profilácticamente antes de la exposición a IHH. Se sugiere que las drogas podrían ejercer su efecto a través de un bloqueo parcial de la producción de eritropoyetina (EPO).
Assuntos
Camundongos , Enalapril , Enalapril/administração & dosagem , Enalapril/efeitos adversos , Enalapril/uso terapêutico , Pentoxifilina , Pentoxifilina/administração & dosagem , Pentoxifilina/efeitos adversos , Pentoxifilina/uso terapêutico , Policitemia , Eritropoetina , Hematócrito , HipóxiaRESUMO
Este estudio se llevó a cabo con el fin de determinar el rol que tiene la llegada de la menopausia en la relación entre las presiones alveolares de O2 y CO2 y el mal de montaña crónico (MMC) o enfermedad de Monge. El estudio se realizó en una muestra poblacional femenina residente de Cerro de Pasco (4300 m) entre 26-62 años de edad (n=41). Se midieron, entre otras, las variables fisiológicas involucradas en la secuencia fisiopatológica del MMC: presiones tidales de O2 y CO2 (PO2T y PCO2T, torr), saturación de oxígenos (SaO2, por ciento), y concentración de hemoglobina (Hb, g/dl). Los resultados mostraron que, en las mujeres de altura después de la menopausia, se observa una disminución de la PO2T (48.4 ñ 3.3 vs 52.7 ñ 3.1 torr, prevalencia < 0.0001) y de la SaO2 (81.9 ñ 4.12 vs 84.7 ñ 3.14 por ciento, prevalencia 0.001), así como un aumento de la PCO2T (34 ñ 2.2 vs 30.4 ñ 3.3 torr, prevalencia < 0.0001) y de la Hb (18.6 ñ 1.7 vs 15.9 ñ 2.3 g/dl; prevalencia < 0.001). En las poblaciones masculinas de altura se observa un aumento de la prevalencia de eritrocitosis excesiva en forma continua con la edad, en el caso de las mujeres de altura, postulamos, en base a nuestros resultados, que un factor contribuyente adicional para la aparición abrupta (y no continua) del MMC sería la disminución de la ventilación, como lo indica el aumento de la PCO2T. Esta, al disminuir, traería como consecuencia hipoxemia y eritrocitosis excesiva, el signo preponderante del MMC.
Assuntos
Humanos , Feminino , Adulto , Doença da Altitude , Substitutos Sanguíneos , Hemoglobinas , Hipóxia , Menopausa , Oxigênio , PolicitemiaRESUMO
This study was designed to determine whether subjects born at high altitude (HA; 2,000 m or above) who subsequently move to near sea level (SL) develop end-tidal PCO2 (PETCO2) and PO2 (PETO2) values that equal those of SL natives living near SL. A total of 108 male HA natives living near SL were identified by survey of a district in Lima, Peru, and a further 108 male SL natives from the same district were identified as control subjects. Of these subjects, satisfactory data for inclusion in the study were obtained from 93 HA and 82 SL subjects. Mean PETCO2 and PETO2 values were 37.7 +/- 2.5 (SD) and 104.7 +/- 3.2 Torr, respectively, in HA subjects and 37.7 +/- 2.2 and 104.8 +/- 3.0 Torr, respectively, in SL subjects. The average difference between SL natives and HA natives for PETCO2 was 0.07 Torr (-0.64 to 0.78; 95% confidence interval) and for PETO2 was 0.05 Torr (-0.89 to 0.99, 95% confidence interval). The average age and weight of the SL and HA subjects did not differ, but the HA subjects were shorter and tended to have larger vital capacities, consistent with their origin at HA. We conclude that the PETCO2 and PETO2 near SL of SL natives and HA natives do not differ.