Assuntos
Corpo Carotídeo/fisiologia , Nervo Glossofaríngeo/fisiologia , Concentração de Íons de Hidrogênio , Transporte de Íons , Transdução de Sinais/fisiologia , Amilorida/análogos & derivados , Amilorida/farmacologia , Animais , Transporte Biológico Ativo/efeitos dos fármacos , Dióxido de Carbono/farmacologia , Corpo Carotídeo/citologia , Corpo Carotídeo/efeitos dos fármacos , Proteínas de Transporte/efeitos dos fármacos , Gatos , Hipóxia Celular/efeitos dos fármacos , Líquido Intracelular/metabolismo , Transporte de Íons/efeitos dos fármacos , Proteínas do Tecido Nervoso/antagonistas & inibidores , Nicotina/farmacologia , Oxigênio/farmacologia , Oxigênio/fisiologia , Transdução de Sinais/efeitos dos fármacos , Sódio/metabolismo , Cianeto de Sódio/farmacologia , Trocador de Sódio e Cálcio , Trocadores de Sódio-Hidrogênio/antagonistas & inibidoresRESUMO
The paper presents new observations on young high altitude natives (Andes and Himalayas), testing the hypothesis that periodic breathing with apnea during sleep is determined by their ventilatory sensitivity to hypoxia and its interaction with the sleep state. The hypothesis is in general supported by the evidence. But, contrary to expectation, the ventilatory sensitivity to hypoxia in the Sherpa children was significantly lower than those in the Andes. Despite that departure, the magnitude of ventilatory periodicity among the subjects was internally consistent with their ventilatory sensitivity to hypoxia. Although the carotid chemosensory input is the pacesetter for the reflexive periodicity, mechanisms in the central nervous system can influence it significantly.
Assuntos
Altitude , Células Quimiorreceptoras/fisiologia , Periodicidade , Respiração/fisiologia , Síndromes da Apneia do Sono/fisiopatologia , Sono/fisiologia , Adolescente , Adulto , Animais , Corpo Carotídeo/fisiologia , Gatos , Criança , Chile/etnologia , Humanos , Nepal/etnologia , Respiração/imunologia , Síndromes da Apneia do Sono/etiologiaRESUMO
"This paper proposes a simple method for evaluating death registration completeness during intercensal periods. It is easier to implement than alternative methods but its main advantage is making explicit the dependence of results on the quality of readily observed demographic variables. Applications are made to data from South Korea and Argentina."
Assuntos
Atestado de Óbito , Estudos de Avaliação como Assunto , Métodos , Projetos de Pesquisa , Estatísticas Vitais , América , Argentina , Ásia , Países em Desenvolvimento , Ásia Oriental , Coreia (Geográfico) , América Latina , Características da População , Pesquisa , América do SulRESUMO
Arterial blood gases, acid-base and hematocrit of six highest inhabitants on Aucanquilcha (5950 m) in Chile were studied. These blood gases were compared with the alveolar gases of highest mountain climbers in Nepal, Sherpas and acclimatized lowlanders, and on average high altitude natives in the Chilean and Peruvian Andes and in the Nepal Himalayas. The mean arterial PCO2 (27.5 Torr) was lower than the standard sea level normal values, indicating a modest hypoxic hyperventilation. The mean arterial pH was 7.400, showing a complete renal compensation of respiratory alkalosis. The mean hematocrit (62%) and hemoglobin (20.7 g/dl) values were greater than the standard sea level values. These blood data showed that the highest inhabitants were acclimatized to hypoxia of their residential altitude. The respiratory gases showed less hyperventilation in the highest inhabitants and Sherpa mountaineers of high altitudes relative to the acclimatized lowlanders. Also, the average high altitude natives in the Andes and Himalayas showed less hyperventilation compared to the acclimatized lowlanders. We conclude that the attenuated hyperventilation is an appropriate respiratory adaptation to high altitude hypoxia in the native high altitude residents, allowing them to conserve metabolic energy expended for hyperventilation and to use the ventilatory reserve for a better performance at greater altitudes.
Assuntos
Altitude , Dióxido de Carbono/sangue , Oxigênio/sangue , Respiração , Adaptação Fisiológica , Adulto , Dióxido de Carbono/fisiologia , Chile , Humanos , Masculino , Montanhismo , Oxigênio/fisiologia , Alvéolos Pulmonares/análiseRESUMO
To evaluate the role of genetic and environmental factors in the genesis of large lungs in high-altitude natives, we measured forced vital capacity (FVC), static lung pressure-volume characteristics and maximum expiratory flow-volume loops in 17- to 20-yr-old Peruvian natives to 3,850 m (highlanders) and 800 m (lowlanders). Forced vital capacity was 5.11 +/- 0.64 liters in highlanders, 116 +/- 11% of predicted; and 3.73 +/- 0.32 liters in lowlanders, 84 +/- 7% of predicted. Lung elastic recoil at functional residual capacity and at total lung capacity, and size-corrected pressure volume curves were similar in the two groups. Despite the larger volumes in highlanders, density-corrected maximum flow rates were similar in highlanders and lowlanders, and flow expressed in FVC'S-S-1 was less in highlanders. Upstream conductance at 50% FVC expressed in fvc's-s-1-cmH2O was 0.094 +/- 0.023 in highlanders vs. 0.147 +/- 0.050 in lowlanders. Flow rates did not change in sojourners to altitude, suggesting that the lower values of highlanders were due to anatomic factors. These findings suggest that airways, which form in fetal life, do not participate in adaptation to altitude, and that the large lungs of highlanders result from postnatal environmental hypoxic stimulation of lung growth. Our results illustrate the importance of "dysynaptic" lung growth in determining patterns of adult lung function.