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Start Over Author "Weiss, J. A." Journal journal of applied physiology
30 results on '"Weiss, J. A."'

23. A new model of chronic intermittent hypoxia in humans: effect on ventilation, sleep, and blood pressure.

Author

R. Tamisier, Gilmartin, G. S., Launois, S. H., Pépin, J. L., Nespoulet, H., Thomas, R., Lévy, P., and Weiss, J. W.

Subjects
HYPOXEMIA, SLEEP apnea syndromes, RESPIRATORY obstructions, BLOOD pressure, OBESITY, HYPERTENSION
Abstract

Obstructive sleep apnea is characterized by repetitive nocturnal upper airway obstructions that are associated with sleep disruption and cyclic intermittent hypoxia (CIH) The cyclic oscillations in O2 saturation are thought to contribute to cardiovascular and other morbidity, but animal and patient studies of the pathogenic link between CIH and these diseases have been complicated by species differences and by the effects of con- founding factors such as obesity, hypertension, and impaired glucose metabolism. To minimize these limitations, we set up a model of nocturnal CIH in healthy humans. We delivered O2 for IS s every 2 mm during sleep while subjects breathed 13% O2 in a hypoxic tent to create 30 cycles/h of cyclic desaturation-reoxygenation [saturation of peripheral O2 (SpO2) range: 95-85%I. We exposed subjects overnight for 8-9 hlday for 2 wk (10 subjects) and 4 wk (8 subjects). CIH exposure induced respiratory disturbances (central apnea hypopnea index: 3.0 ± 1.9 to 31.1 ± 9.6 events/h of sleep at 2 wk). Exposure to CIH for 14 days induced an increase in slopes of hypoxic and hypercapnic ventilatory responses (1.5 ± 0.6 to 3.1 ± 1.2 1·min-1% drop in SpO2 and 2.2 ± 1.0 to 3.3 ± 0.9 1·min-1·mmHg CO2-1, respectively), consistent with hypoxic acclimatization. Waking normoxic arterial pressure increased significantly at 2 wk at systolic (114 ± 2 to 122 ± 2 mmHg) and for diastolic at 4 wk (71 ± 1.3 to 74 ± 1.7 mmHg). We propose this model as a new technique to study the cardiovascular and metabolic consequences of CIH in human volunteers. [ABSTRACT FROM AUTHOR]

Published
2009
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24. Exposure to cyclic intermittent hypoxia increases expression of functional NMDA receptors in the rat carotid body.

Author

Yuzhen Liu, En-Sheng Ji, Shuanglin Xiang, Tamisier, Renaud, Jingli Tong, Jianhua Huang, and Weiss, J. Woodrow

Subjects
HYPOXEMIA, METHYL aspartate, CAROTID artery, CHEMICAL senses, NEUROTRANSMITTERS, RATS
Abstract

Although large quantities of glutamate are found in the carotid body, to date this excitatory neurotransmitter has not been assigned a role in chemoreception. To examine the possibility that glutamate and its N-methyl-D-aspartate (NMDA) receptors play a role in acclimatization after exposure to cyclic intermittent hypoxia (CIH), we exposed male Sprague-Dawley rats to cyclic hypoxia or to room air sham (Sham) for 8 k/day for 3 wk. Using RT-PCR, Western blot analysis, and immunohistochemistry, we found that ionotropic NMDA receptors, including NMDAR1, NMDAR2A, NMDAR2A/2B, are strongly expressed in the carotid body and colocalize with tyrosine hydroxylase in glomus cells. CIH exposure enhanced the expression of NMDAR1 and NMDAR2A/2B but did not substantially change the level of NMDAR2A. We assessed in vivo carotid sinus nerve activity (CSNA) at baseline, in response to acute hypoxia, in response to infused NMDA, and in response to infused endothelin-1 (ET-1) with and without MK-801, an NMDA receptor blocker. Infusion of NMDA augmented CSNA in CIH rats (124.61 ± 2.64% of baseline) but not in sham-exposed rats. Administration of MK-801 did not alter baseline activity or response to acute hypoxia, in either CIH or sham animals but did reduce the effect of ET-1 infusion on CSNA (CSNA after ET-1 = 160.96 ± 8.05% of baseline; ET-1 after MK-801 = 118.56 ± 9.12%). We conclude that 3-wk CIH exposure increases expression of NMDA functional receptors in rats, suggesting glutamate and its receptors may play a role in hypoxic acclimatization to CIH. [ABSTRACT FROM AUTHOR]

Published
2009
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