Margaret S Jacobi

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The effect of maturation and motor activity on recovery from hypoxic apnea by gasping (autoresuscitation) was investigated in Swiss Webster mice and a SW-related strain. Apnea was induced with 97% N2-3% CO2 and air given at its onset. In 69 Swiss Webster-related strain mice that gasped for at least 5s, the survival rates were 100% in 1- to 16-day-old mice,(More)
Mechanisms underlying failure of autoresuscitation from hypoxic apnea were investigated. Failure was induced by repeated exposure to hypoxia. The influence of maturation was studied in adults, weanlings, and 10- and 5-day-old mice. Mice successful at autoresuscitation (BALB/c) as well as those prone to autoresuscitation failure (SWR weanlings) were studied.(More)
The mechanism of failure of autoresuscitation from hypoxic apnea in 17- to 23-day-old (weanling) Swiss Webster related/J mice was investigated by recording electrocardiogram (ECG) and ventilation in adult, weanling, and 11-day-old mice. Hypoxic apnea was induced with 97% N2-3% CO2. O2 (21% or 50% O2) or 97% N2-3% CO2 was given at the onset of apnea. The ECG(More)
1. Rapid steady-state CO2 responses were determined in six normal subjects at rest and five subjects at four different work loads up to 125 W, by injecting pure CO2 at constant flow into a small mixing chamber in the inspiratory limb of a breathing circuit. 2. The time course of the response of ventilation (V) and mean alveolar PCO2 (PACO2) was checked in(More)
Almitrine has potential as a tool for testing the physiological role of the peripheral chemoreceptor. The effects of almitrine on CO2 chemosensitivity were studied at rest and during light exercise using a constant inflow technique that avoids the hyperoxia of rebreathing methods. The steady-state ventilatory response to CO2 was measured in two groups of(More)
ABSTRACT: The maturation of the process of spontaneous recovery from hypoxic apnea by gasping (autoresuscitation) was characterized in adult, weanling (18-22 d), and infant (5 and 10 d) BALB/c mice. ECG and respiration were recorded and hypoxic apnea was induced with 97% N2-3% CO2. Administration of 21% O2 at onset of hypoxic apnea resulted in successful(More)
We studied six patients with symptomatic hyperventilation, using new techniques to quantify baseline variability of respiratory variables, and to assess CO2 sensitivity around the control point using a stimulus not detectable by the subject. We compared them with six normal subjects and six patients with mild asthma. Symptomatic hyperventilators had normal(More)
The effect of pentobarbital anaesthesia on spontaneous recovery from hypoxic apnoea (autoresuscitation) was investigated in SWR/J mice. Experiments were performed in 17 to 23 day old animals, in which the mechanism often fails, and in adults, in which it is usually successful. Mice, matched for age and weight, were injected with pentobarbital (62.5 mg/kg)(More)
Rapid steady-state CO2 responses were determined in five normal adults at rest and at up to six levels of exercise by injecting pure CO2 at a constant flow into the inspiratory limb of a breathing circuit. Ventilation (V) was measured with a dry gas meter and PCO2 at the mouth was recorded by a mass spectrometer. Mean alveolar PCO2 (PACO2) was taken as(More)
1. The transient ventilatory response to CO2, measured using short pulses at constant inflow, was compared with the steady-state response at rest and during exercise at 50 W, and with the rebreathing response at rest, in nine healthy subjects. At rest CO2 was given at flow rates of 0.2 and 0.4 l min-1 and during exercise, to compensate for the smaller(More)