Short-term potentiation of ventilation after different levels of hypoxia

• Published in: Journal of applied physiology (1985) Vol. 86; no. 5; pp. 1478 - 1482
• Main Authors: Menendez, Astryd A, Nuckton, Thomas J, Torres, Jose E, Gozal, David
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.05.1999; American Physiological Society
• Subjects: Adult; Algorithms; Biological and medical sciences; Body fluids; Carbon Dioxide - metabolism; Cardiorespiratory control. Arterial mecano- and chemoreceptor; Female; Fundamental and applied biological sciences. Psychology; Gases; Humans; Hypoxia - physiopathology; Lungs; Male; Oxygen Consumption; Respiratory Function Tests; Respiratory Mechanics - physiology; Respiratory system; Space life sciences; Vertebrates: respiratory system; Short term; Human; Potentiation; Oxygen; Environmental factor; Hypoxia; Pulmonary ventilation; Respiration; Respiratory control; Respiratory system
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1999.86.5.1478

Constance S. Kaufman Pulmonary Research Laboratory, Departments of 1  Pediatrics and 2  Physiology, Tulane University School of Medicine, New Orleans, Louisiana 70112 Short-term potentiation of ventilation (VSTP) may be observed in healthy subjects on sudden termination of an hypoxic stimulus. We hypothesized that the level of hypoxia preceding normoxia would modify the duration and magnitude of the ensuing ventilatory decay. Ten healthy adults were studied on two different occasions, during which they were randomly exposed to isocapnic 6 or 10% O 2 for 60 s and then switched to an isocapnic normoxic gas mixture. Both hypoxic gases induced significant ventilatory responses, and mean peak minute ventilation before the isocapnic normoxic switch was higher in 6% O 2 ( P  < 0.001). The fast time constant of the two-exponential equation representing the best fit for ventilatory decay was unaffected by the magnitude of the hypoxic stimulus. However, the slow time constant, which is considered to represent VSTP, was markedly prolonged in 6% compared with 10% O 2 [106.7 ± 11.3 vs. 38.2 ±   6.1 (SD) s, respectively; P  < 0.0001]. This result indicates that VSTP is stimulus dependent. We conclude that the magnitude of hypoxia preceding a normoxic transient modifies VSTP characteristics. We speculate that the interdependence function of ventilatory stimulus and short-term potentiation is crucial for preservation of system stability during transitions from high to low ventilatory drives. respiratory afterdischarge; isocapnia; normoxia; afterdischarge