Oxygen intake, ventilation and heart rate were measured in six subjects performing ergometer exercise at various altitudes from sea level to 7,440 m (24,400 ft) (Bar. 300 mm Hg) during a Himalayan expedition lasting 8 months. intake for given work was constant independent of altitude, up the maximum that could be maintained 5 min. Maximum oxygen declined with increase reaching 1.46 liters/min best subject. Ventilation (STPD) altitude light moderate but increased each as approached. values...

At very high altitude, exercise performance in the human sojourner may depend on a sufficient hypoxic ventilatory response (HVR). To study relationship of HVR to at we studied sea level and 5,400 m ventilation level, m, 6,300 nine members American Medical Research Expedition Everest. The between individuals was maintained when repeated after acclimatization (P less than 0.05). There significant correlation all subjects equivalent during (r = 0.704, P Subjects were then grouped into (H) low...

The effect on carotid chemoreceptor afferents of oligomycin, an inhibitor mitochondrial oxidative phosphorylation that does not affect energy conservation, was studied in 20 cats were anesthetized, paralyzed, and artificially ventilated. Responses single or a few to changes arterial O2 tension (PaO2) at constant CO2 recorded. In addition, responses nicotine, cyanide, antimycin A carbonyl cyanide p-tri-fluoromethoxyphenylhydrazone (FCCP) tested normoxia. Oligomycin (50-500 microgram)...

The ventilatory response to acute hypoxia (transient nitrogen inhalation) was compared in cyanotic congenital heart disease, noncyanotic disease and normal subjects; two of six subjects, the reassessed after cardiac defects were repaired. Ventilatory responses quantitated by relating maximum increase ventilation decrease arterial oxygen saturation for each period inhalation. subjects significantly less than normal, a direct relation found between degree chronic hypoxemia reduction hypoxia....

ABSTRACT The present study was undertaken to elicit the temporal sequence of changes in cardiovascular and respiratory function during aestivation. Twelve lungfish (2–6 kg) equipped with ECG electrodes, arterial buccal cannulae, were studied while aestivating mud or artificial cloth-bag nests. periods observation ranged from 0·5 9·5 months. mean blood pressure gradually decreased control values 20–28 mm Hg a range 14–18 mmHg first 30 days aestivation, whereas heart rate dropped more (22–30...

Arterial oxygen saturations were measured on six members of the Himalayan Scientific and Mountaineering Expedition, 1960–61, during a wintering period at 19,000 ft (5,800 m; Pb 380 mm Hg). The determinations made by ear oximetry analysis venous blood from heated hand rest exercise work levels up to 1,200 kg-m/min. Expired gas volumes concentrations also measured. average arterial saturation was 67%, 300 900 kg-m/min it 63 56%, respectively. Several readings less than 50% recorded severe...

Barometric pressures were measured on Mt. Everest from altitudes of 5,400 (base camp) to 8,848 m (summit) during the American Medical Research Expedition Everest. Measurements at made with a mercury barometer, and above this most obtained an accurate crystal-sensor barometer. The mean daily 400.4 +/- 2.7 (SD) Torr (n = 35) m, 351.0 1.0 16) 6,300 283.6 1.5 6) 8,050 253.0 1) m. All these are considerably higher than those predicted ICAO Standard Atmosphere. chief reason is that between 2 16 km...

The time-dependent effects of hypoxia on the discharge rate carotid chemoreceptors were measured in anesthetized cats. Hypoxic exposure two different durations used: a short-term (2–3 h) was used to measure response same chemoreceptors; and long-term (28 days at inspired PO2 70 Torr) study chemoreceptor properties one group cats relative those control group. In chronically hypoxic groups, determinations made 1) steady-state responses four levels arterial (PaO2) constant PCO2; 2) acute...

The effects of carbon monoxide inhalation and consequent carboxyhemoglobinemia (HbCO) on the discharge rates aortic body carotid chemoreceptor afferents were investigated in 18 anesthetized cats. In 10 experiments both activities monitored simultaneously. Carbon during normoxia always stimulated chemoreceptors before chemoreceptors, steady-state response to HbCO was greater than that most chemoreceptors. Only 2 fibers tested showed a distinct increase activity moderate increases HbCO%. Thus,...

To evaluate the role of genetic and environmental factors in genesis large lungs high-altitude natives, we measured forced vital capacity (FVC), static lung pressure-volume characteristics maximum expiratory flow-volume loops 17- to 20-yr-old Peruvian natives 3,850 m (highlanders) 800 (lowlanders). Forced was 5.11 +/- 0.64 liters highlanders, 116 11% predicted; 3.73 0.32 lowlanders, 84 7% predicted. Lung elastic recoil at functional residual total capacity, size-corrected pressure volume...

The validity of the concept relating blood oxygen affinity and alveolar ventilation to body weight in homeothermic mammals was reexamined with pH used as fixed variable. Blood Po2 at 50% saturation 7.4 (P50(7.4)) PCO2 oxygenated (PCO2(7.4)) from a variety were determined 37 degrees C by vitro equilibration techniques. In some species, arterial PCO2, PO2, also measured. PCO2(7.4), which similar showed correlation coefficient +0.33 over range 28-100,000 g +0.90 among species under 200 g....

A quantitative comparison of the responses between aortic and carotid chemoreceptors to steady-state levels arterial CO2 O2 partial pressure was made in 35 cats anesthetized, paralyzed, artificially ventilated. The measurements on two receptors were simultaneously 6 separately 29 cats. response a stimulus fraction that chemoreceptors, hypoxia relatively blunted. differences are rather than qualitative. Since low is known attenuate hypoxic it suggested body responsible for their blunted response.

Responses to acute arterial blood pressure changes of a single or few chemoreceptor afferents from the aortic body and carotid at constant gases pH were measured in 16 adult cats. During normocapnic normoxia moderate hypoxia (arterial oxygen tension 60 Torr) an induced hypotension 80 Torr increased strikingly discharge rate all chemoreceptors but not most chemoreceptors; down level 50 stimulated only slightly. Hyperoxia eliminated stimulatory effect this degree on it did affect same extent....

THE VENTILATORY RESPONSE TO HYPOXIA WAS STUDIED IN TWO GROUPS OF SUBJECTS WITH ABNORMAL SYMPATHETIC NERVOUS CONTROL: (a) human subjects with familial dysautonomia (Riley-Day syndrome), and (b) unanesthetized goats treated an alpha-adrenergic blocking agent (phenoxybenzamine). The ventilatory response to hypoxia was evaluated in two ways: from the slope of relationship between ventilation alveolar P(Co2) ([unk]V(E)-P(ACo2) slope) during rebreathing hypoxic hyperoxic gases, change produced...

Upon entering into aestivation, Protopterus aethiopicus develops a respiratory acidosis. A slow compensatory increase in plasma bicarbonate suffices only to partially restore arterial pH toward normal. The cessation of water intake from the start aestivation results hemoconcentration and marked oliguria. concentrations most constituents continue progressively, electrolyte ratios change. urea concentration is disproportionately high for degree dehydration constitutes an increasing fraction...