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Biomedical subjects

O Appenzeller

Publications and source records attributed to O Appenzeller.

At least 19 recordsLinked to original sources
PubMed2005

Cerebrovascular responses to hypoxia and hypocapnia in high-altitude dwellers.

Cerebral blood flow is known to increase in response to hypoxia and to decrease with hypocapnia. It is not known, however, whether these responses are altered in high-altitude dwellers who are not only chronically hypoxic and hypocapnic, but also polycythaemic. Here we examined cerebral blood flow responses to hypoxia and hypocapnia, separately and together, in Andean high-altitude dwellers, including some with chronic mountain sickness (CMS), which is characterized by excessive polycythaemia. Studies were carried out at high altitude (Cerro de Pasco (CP), Peru; barometric pressure (P(B)) 450 mmHg) and repeated, following relief of the hypoxia, on the day following arrival at sea level (Lima, Peru; P(B) 755 mmHg). We compared these results with those from eight sea-level residents studied at sea level. In nine high-altitude normal subjects (HA) and nine CMS patients, we recorded middle cerebral artery mean blood flow velocity (MCAVm) using transcranial Doppler ultrasonography, and expressed responses as changes from baseline. MCAVm responses to hypoxia were determined by changing end-tidal partial pressure of oxygen (P(ET,O2)) from 100 to 50 mmHg, with end-tidal partial pressure of carbon dioxide clamped. MCAVm responses to hypocapnia were studied by voluntary hyperventilation with (P(ET,O2)) clamped at 100 and 50 mmHg. There were no significant differences between the cerebrovascular responses of the two groups to any of the interventions at either location. In both groups, the MCAVm responses to hypoxia were significantly greater at Lima than at CP (HA, 12.1 +/- 1.3 and 6.1 +/- 1.0%; CMS, 12.5 +/- 0.8 and 5.6 +/- 1.2%; P < 0.01 both groups). The responses at Lima were similar to those in the sea-level subjects (13.6 +/- 2.3%). The responses to normoxic hypocapnia in the altitude subjects were also similar at both locations and greater than those in sea-level residents. During hypoxia, both high-altitude groups showed responses to hypocapnia that were significantly smaller at Lima than at CP (HA, 2.17 +/- 0.23 and 3.29 +/- 0.34% mmHg(-1), P < 0.05; CMS, 1.87 +/- 0.16 and 3.23 +/- 0.24% mmHg(-1); P < 0.01). The similarity of the results from the two groups of altitude dwellers suggests that haematocrit is unlikely to greatly affect cerebrovascular reactivity to hypoxia and hypocapnia. The smaller vasodilatation to hypoxia and larger vasoconstriction to hypoxic hypocapnia at high altitude suggest that cerebrovascular responses may be impaired at the high altitude, i.e. a maladaptation. The changes in the responses within less than 24 h at sea level indicate that this impairment is rapidly reversible.

Acclimatization↗
PubMed2005

A hypothesis: autonomic rhythms are reflected in growth lines of teeth in humans and extinct archosaurs.

A major determinant of tooth architecture is the arrangement of lines in dentin and in the enamel following the contour of the surface. Since the original description of these lines in the 19th century, they have been attributed to recurring events during tooth development. They have also attracted the attention of dental scientists and anthropologists; however, to date, studies of these structures have been largely theoretical and microscopic. We show here that the statistical properties of the spacing between the lines are similar in teeth from both ancient and modern humans and from extinct archosaurs, reptiles that lived tens or hundreds of millions of years ago-they also resemble heart rate variability of living humans. We propose that the deposition of these recurring structures is controlled by the autonomic nervous system. This control accounts for their regularity and recurrent nature and implies that the lines are an expression of a biologic rhythm which has been conserved throughout evolution. Details of the rhythms give clues to life styles in ancient civilizations and to the physiology of extinct archosaurs.

Animals↗
PubMed2005

Migraine in the Andes and headache at sea level.

In Cerro de Pasco (CP), Peru (altitude 4338 m) 24% of men have migraine with aura. We studied 30 men. Twenty CP natives, examined in CP, were rated using a chronic mountain sickness (CMS) score to separate controls (10) from those with CMS (10), a maladaptation syndrome in natives to altitude which includes severe, recurring headache. We collected white cells in CP and, from the same men, within 1 h of arrival in Lima (150 m above sea level). Ten normal US men volunteered white cells for comparison. After RNA extraction we assessed gene expression by reverse transcription-polymerase chain reaction. Low ATP1A1 subunit of the ATPase gene mRNA expression in CP was correlated with headache (P=0.002), acral paraesthesias (P=0.004) and CMS score (P<0.001). ATP1A1 subunit expression was increased in all Andeans in Lima (P<0.001). There were no differences between Andean controls in Lima and US controls. Manipulation of Na+/K+ATPase could offer relief for migraineurs at sea level.

Adult↗
PubMed2004

Cardiovascular responses to orthostatic stress in healthy altitude dwellers, and altitude residents with chronic mountain sickness.

High altitude (HA) dwellers have an exceptionally high tolerance to orthostatic stress, and this may partly be related to their high packed cell and blood volumes. However, it is not known whether their orthostatic tolerance would be changed after relief of the altitude-related hypoxia. Furthermore, orthostatic tolerance is known also to be influenced by the efficiency of the control of peripheral vascular resistance and by the effectiveness of cerebral autoregulation and these have not been reported in HA dwellers. In this study we examined plasma volume, orthostatic tolerance and peripheral vascular and cerebrovascular responses to orthostatic stress in HA dwellers, including some with chronic mountain sickness (CMS) in whom packed cell and blood volumes are particularly large. Eleven HA control subjects and 11 CMS patients underwent orthostatic stress testing, comprising head-up tilting with lower body suction, at their resident altitude (4338 m) and at sea level. Blood pressure (Portapres), heart rate (ECG), brachial and middle cerebral artery blood velocities (Doppler) were recorded during the test. Plasma volumes were found to be similar in both groups and at both locations. Packed cell and blood volumes were higher in CMS patients than controls. All subjects had very good orthostatic tolerances at both locations, compared to previously published data in lowland dwellers. In CMS patients responses of forearm vascular resistance to the orthostatic stress, at sea level, were smaller than controls (P < 0.05). Cerebral blood velocity was less in CMS than in controls (P < 0.01) and, at sea level, it decreased more than the controls in response to head-up tilting (P < 0.02). Cerebral autoregulation, assessed from the relationship between cerebral pressure and velocity, was also impaired in CMS patients compared to HA controls, when examined at sea level (P < 0.02). These results have shown that the good orthostatic tolerance seen in high altitude dwellers at altitude is also seen at sea level. There was no difference in orthostatic tolerance between CMS patients, with their exceptionally large blood volumes, and the HA controls. This may be because peripheral vascular and cerebrovascular responses (at least at sea level) are impaired in the CMS patients relative to HA controls. Thus, the advantage of the large blood volume may be offset by the smaller vascular responses.

Adaptation, Physiological↗
PubMed2004

Orthostatic tolerance and blood volumes in Andean high altitude dwellers.

Orthostatic tolerance is a measure of the ability to prevent hypotension during gravitational stress. It is known to be dependent on the degree of vasoconstriction and the magnitude of plasma volume, but the possible influence of packed cell volume (PCV) is unknown. High altitude residents have high haematocrits and probably high packed cell volumes. However, it is not known whether plasma volume and blood volume are affected, or whether their orthostatic tolerance is different from low altitude residents. In this study we determined plasma volume, PCV and orthostatic tolerance in a group of high altitude dwellers (HA), including a subgroup of highland dwellers with chronic mountain sickness (CMS) and extreme polycythaemia. Plasma volume and PCV were determined using Evans Blue dye dilution and peripheral haematocrit. Orthostatic tolerance was assessed as the time to presyncope in a test of head-up tilting and lower body suction. All studies were performed at 4338 m. Results showed that plasma volumes were not significantly different between CMS and HA, or in highland dwellers compared to those seen previously in lowlanders. PCV and haematocrit were greater in CMS than in HA. Orthostatic tolerance was high in both CMS and HA, although the heart rate responses to orthostasis were smaller in CMS than HA. Orthostatic tolerance was correlated with haematocrit (r= 0.57, P < 0.01) and PCV (r= 0.54, P < 0.01). This investigation has shown that although high altitude residents have large PCV, their plasma volumes were similar to lowland dwellers. The group with CMS have a particularly large PCV and also have a very high orthostatic tolerance, despite smaller heart rate responses. These results are compatible with the view that PCV is of importance in determining orthostatic tolerance.

Adult↗
PubMed2004

Cerebral vasoreactivity in Andeans and headache at sea level.

Headache is common in Cerro de Pasco (CP), Peru (altitude 4338 m) and was present in all patients with chronic mountain sickness (CMS) in CP reported here. Forty-seven percent of inhabitants report headache. Twenty-four percent of men have migraine with aura, with an average of 65 attacks a year. We assessed vasoreactivity of the cerebral vessels to CO2 by rebreathing and to NO by the administration of isosorbite dinitrate (IDN), a nitric oxide (NO) donor, using transcranial Doppler ultrasound in the middle cerebral artery (MCA) in natives of CP, some of whom suffered from CMS. We repeated the measurements in Lima (altitude 150 m) in the same subjects within 24 h of arrival. Vasodilatation in the middle cerebral artery supply territory in response to CO2 and NO, both physiologic vasodilators, is defective in Andean natives at altitude and in the same subjects at sea level. Incapacitating migraine can occur with impaired cerebral vasoreactivity to physiologic vasodilators. We propose that susceptibility to migraine might depend in part on gene expression with consequent alterations of endothelial function.

Altitude↗
PubMed2002

Acral paresthesias in the Andes and neurology at sea level.

BACKGROUND: Thirty-nine percent of permanent altitude dwellers in the Andes experience acral paresthesias. METHODS: Clinical examinations, sural nerve biopsies, and electrodiagnostic studies on peripheral nerves were performed on 15 men. Ten Cerro de Pasco (CP) natives living at 4,338 meters were biopsied. Three of these subjects had no burning feet/burning hands (BF/BH); three had BF/BH; and four had chronic mountain sickness (CMS), a maladaptation syndrome resulting from living in the Andes, all with BF/BH. Three patients with CMS were biopsied in Lima within hours after leaving CP. Two normal Lima natives were biopsied in Lima. Symptom scores for BF/BH and CMS score ratings were used. The nerves were assayed for Na+, K+ adenosine triphosphatase (ATPase), cytochrome oxidase (CO), substance P (SP), and endothelin (ET). RESULTS: Low ATPase was inversely related to symptom scores and CMS scores (p < 0.001). Patients with CMS biopsied in normoxia (Lima) had ATPase levels similar to those of controls. Nerve motor conduction velocities and sensory action potentials were normal. CO was inversely related to age (p < 0.03) and no relation of SP to any variable was found. ET levels were lower in sea level natives (p = 0.04). CONCLUSIONS: Acral paresthesias are associated with low ATPase in peripheral nerves. Lower ET levels of sea level natives likely reflect lowered release from vasa nervorum.

Adult↗
PubMed2002

Fos and nitric oxide synthase in rat brain with chronic mesostriatal dopamine deficiency: effects of nitroglycerin and hypoxia.

We found sustained proto-oncogene c-fos expression in neurons of the lateral and medial neostriatum and suppression of this expression in nitric oxide synthase (NOS)-containing cells within the islands of Calleja after lesions of the dopaminergic mesostriatal system induced by 6-hydroxydopamine. Systemic administration of nitroglycerin (NTG) or mild hypoxia resulted in a decreased of c-fos expression in the dorsolateral part of the denervated neostriatum. However, in other brain structures NTG or mild hypoxia evoked sustained c-fos expression in NOS-containing neurons and in the sources catecholaminergic projections involved in the control of cardiovascular function. We propose that the administration of NTG, an NO donor, or hypoxia partially attenuate the consequences of an excessively increased glutamate level in the denervated neostriatum which are manifest in high level of c-fos expression.

Animals↗
PubMed2001

Respiratory and cardiovascular adaptations to progressive hypoxia; effect of interval hypoxic training.

AIM: Interval hypoxic training was proposed as a technique for adapting hypoxia of various origins. Its effects on the hypoxic ventilatory response and on cardiovascular autonomic control are unknown. METHODS AND RESULTS: We recorded ventilation, end-tidal oxygen (PETO2) and carbon dioxide partial pressures, RR interval and blood pressure during progressive isocapnic hypoxia, before and after 14 days of: (a) interval hypoxic training (three to four periods of 7 min progressive hypoxia in 1 h, each day) in 12 healthy men (training group); (b) breathing into a spirometer by six age-matched male controls. The hypoxic ventilatory response was estimated by the hyperbolic relationship between PETO2 and ventilation (shape factor A). Spectral analysis was used to characterize low- (mainly sympathetic) and high-frequency (vagal) cardiovascular fluctuations. Shape factor A was increased in the interval hypoxic training group from 268+/-59 to 984+/-196 l x mmHg(-1)(P<0.003), but not in the control group (from 525+/-180 to 808+/-245 l x mmHg(-1), P=ns). Before interval hypoxic training, progressive hypoxia decreased, to a similar extent in both groups, mean RR, RR variability and high-frequency power. After interval hypoxic training, RR still decreased significantly, but the decrease in RR variability and high-frequency power was no longer significant in the training group. No significant changes were observed in blood pressure fluctuations. No changes were observed in the control group. CONCLUSIONS: Two weeks of interval hypoxic training increased the hypoxic ventilatory response, in association with reduced vagal withdrawal during progressive hypoxia.

Adult↗
PubMed2001

Breathing patterns and cardiovascular autonomic modulation during hypoxia induced by simulated altitude.

OBJECTIVE: To assess the influence of different breathing patterns on autonomic cardiovascular modulation during acute exposure to altitude-induced hypoxia. DESIGN: We measured relative changes in minute ventilation (VE), oxygen saturation (%SaO2), spectral analysis of RR interval and blood pressure, and response to stimulation of carotid baroreceptors (neck suction) at baseline and after acute (1 h) hypobaric hypoxia (equivalent to 5,000 m, in a hypobaric chamber). METHODS: We studied 19 human subjects: nine controls and 10 Western yoga trainees of similar age, while breathing spontaneously, at 15 breaths/min (controlled breathing) and during 'complete yogic breathing' (slow diaphragmatic + thoracic breathing, approximately 5 breaths/min) in yoga trainees, or simple slow breathing in controls. RESULTS: At baseline %SaO2, VE and autonomic pattern were similar in both groups; simulated altitude increased VE in controls but not in yoga trainees; %SaO2 decreased in all subjects (P< 0.0001), but more in controls than in yoga trainees (17 versus 12%, 14 versus 9%, 14 versus 8%, all P< 0.05 or better, during spontaneous breathing, controlled breathing and yogic or slow breathing, respectively). Simulated altitude decreased RR interval (from 879 +/- 45 to 770 +/- 39, P < 0.01) and increased indices deducted from spectral analysis of heart rate variability (low frequency/high frequency (LF/HF) ratio from 1.6 +/- 0.5 to 3.2 +/- 1.1, P < 0.05) and systolic blood pressure (low-frequency fluctuations from 2.30 +/- 0.31 to 3.07 +/- 0.24 In-mmHg2, P< 0.05) in controls, indicating sympathetic activation; these changes were blunted in yoga trainees, and in both groups during slow or yogic breathing. No effect of altitude was seen on stimulation of carotid baroreceptors in both groups. CONCLUSIONS: Well-performed slow yogic breathing maintains better blood oxygenation without increasing VE (i.e. seems to be a more efficient breathing) and reduces sympathetic activation during altitude-induced hypoxia.

Adult↗
PubMed2001

Neurology in ancient faces.

BACKGROUND: Clinical paleoneurology is almost non-existent, but recognition of neurological diseases in ancient people might be possible by scrutinising portraits apparently representing people as they appeared in life. METHODS: About 200 mummy portraits painted in colour at the beginning of the first millennium were examined. Thirty two skulls excavated at Hawara in the Fayum (northern Egypt), where most of the portraits were found were measured, and nine caliper measures on each side of the skulls were taken. The right/left ratios were statistically analyzed by analysis of variance (ANOVA). One skull was subjected to 3D CT scanning and transilluminated. RESULTS: Two patients were found with progressive facial hemiatrophy (Parry-Romberg syndrome), three with deviations of the visual axes (tropia) and one with oval pupils (corectopia). CONCLUSIONS: Clinical paleoneurology is possible in the absence of a living nervous system. The patients probably had focal epilepsy, hemiplegic migraine, and autonomic nervous system dysfunction.

Facial Asymmetry↗
PubMed2000

Neurological manifestations in chronic mountain sickness: the burning feet-burning hands syndrome.

OBJECTIVE: To characterise the clinical features and nerve biopsy findings in patients with chronic mountain sickness (CMS) living in the Peruvian Andes, with particular attention to the occurrence of the "burning feet-burning hands" syndrome. METHODS: Symptoms and signs were documented clinically in 10 patients with CMS and compared with those in five healthy subjects all living at 4338 metres altitude. Sural nerve biopsies were obtained from three patients with CMS. The nerve fibre population and endoneurial microvessels were analyzed morphometrically. RESULTS: All patients with CMS experienced burning and tingling paraesthesiae in the distal parts of their limbs. Similar but milder symptoms confined to the feet occurred in four of five controls. Three patients with CMS had a mild sensory neuropathy on examination, controls were clinically normal. Nerve biopsies showed a mild demyelinating neuropathy in all three with a reduction in the unmyelinated axon population in one. The endoneurial blood vessels showed a reduced thickness in the basal laminal zone compared with control values but were otherwise normal. CONCLUSIONS: Apart from well recognised symptoms and signs of CMS, the study has shown that such patients may also exhibit a mild sensory neuropathy. Its relation to the burning feet-burning hands syndrome, which was not confined to the patients but was also found in controls at altitude, is uncertain. The time course and pattern of the centrifugal resolution of the burning paraesthesiae complex on low altitude sojourn of high altitude natives raises the possibility that a mechanism involving altered axonal transport may be involved. The reduced thickness of the basal laminal zone of microvessels implies that adaptive structural changes to hypobaric hypoxia may also occur in peripheral nerve and are similar to those reported in other tissues of high altitude natives.

Aged↗
PubMed2000

[The nitric oxide system in a chronic deficiency of mesostriatal dopamine: the action of nitroglycerin].

Unilateral chronic deficiency in dopamine was induced by injection of the neurotoxin 6-hydroxydopamine into the mesostriatum of male Wistar rats (n = 15). The content of the nitric oxide metabolite--NO2- was three time less than in controls in the neostriatum on the operated side only, whereas, in the heart, aorta and plasma it was reduced by 1.9, 1.7 and 3.2 times, respectively. Four hours after subcutaneous injection of nitroglycerin (10 mg/kg, n = 4), a significant 6 fold increase in NO2- content in the neostriatum in the operated hemisphere and 2 fold increase on the in the intact side was observed. In heart, aorta and plasma NO2- content increased 2, 9, 3 times, respectively. The same dose of nitroglycerin given to intact rats (n = 4) had less effect on NO2- content: a 2 fold increase in heart, aorta and plasma only. Activity of NO-synthase (NOS) in animals with dopamine deficiency was reduced 2.7 fold in the neostriatum of the operated hemisphere and by 1.8 time on the intact side, in heart and aorta--by 1.8 and 3 time, respectively. Injection of nitroglycerin increased activity of NOS in the neostriatum of the operated hemisphere 2 fold and on the intact side 3 time; in heart (11 time) and aorta (1.3 time) after 4 hours. Similarly subcutaneous nitroglycerin injection restored the reduced endothelium-dependent vasodilator responses characteristic of the rats with mesostriatal dopamine deficiency. Thus the amplitude of acetylcholine-induced smooth muscles relaxation of the aorta increased by more than 70%. In these animals the injection of nitroglycerin also exerted a normalizing effect on the characteristic apomorphine-induced behaviour asymmetry (rotatory movements). On week after the injection of nitroglycerin the rotatory behaviour was reduced by 20.7% of control rotations. We show that nitroglycerin, a NO-donor, is a useful drug. It correct the abnormalities in the metabolic pathways on NO synthesis in a variety of tissues, endothelium-derived vascular responses and also the behaviour abnormalities induced by unilateral mesostriatal lesions. Our experimental animals are thought to be a model of human hemi-Parkinsonism. Thus nitroglycerin might be of use in Parkinson's disease.

Animals↗
PubMed1999

[The nitrous oxide system under conditions of chronic cerebral dopamine deficiency and hypoxia].

Acute experiments were conducted on adult Wistar rats two months after unilateral microinjection of the 6-hydroxydopamine into the medial forebrain bundle. This led to a greater than 90% decrease of dopamine, fell by 70% of the content of the stable metabolite of nitric oxide-nitrite anion and by up to 80% of nitric oxide synthase activity in the lesioned neostriatum. Nitric oxide synthase activity fell by 30% in the heart, by 60% in the aorta, while nitrite anion decreased in the heart and aorta, in blood plasma and erythrocytes by 45%, 40%, 70%, 30% compared with controls rats, respectively. Lesioned rats also showed changes in the pattern of responses of the smooth muscle of the aorta predominantly to endothelium-dependent (acetylcholine), rather than to endothelium-independent (nitroprusside) vasoreactivity. The amplitude of acetylcholine-induced relaxation of aortic smooth muscle decreased 4-fold, the rate of this response decreased 5-fold and the latent period increased 4-fold. Exposure of lesioned rats, controls rats to moderate hypoxia for 30 min resulted in a rise of nitrite anion content in all tissues; it increased 2-fold in erythrocytes of lesioned rats vs controls rats, in the lesioned and unlesioned neostriatum hypoxia restored the values to controls, while in the heart, aorta and plasma the levels were also increased but did not reach control values. Hypoxia also led to a rise of nitric oxide synthase activity in both lesioned rats and controls rats. However, compared to normoxia, the levels increased over 2 times in the lesioned neostriatum and in the heart, whereas in controls the increase was less that 2-fold. Hypoxia resulted in partial normalization of the functional deficit in endothelium-dependent dilatory responses of aortic smooth muscle. We conclude that the disturbances in nitric oxide system induced by mesostriatal dopaminergic lesions in animals may have relevance to Parkinson's disease. The improvement with ambient hypoxia in quantitative and functional aspects of the disturbances in nitric oxide system may also have relevance in the management of the disease.

Animals↗
PubMed1998

Cardiovascular autonomic modulation and activity of carotid baroreceptors at altitude.

1. To assess the effects of acute exposure to high altitude on baroreceptor function in man we evaluated the effects of baroreceptor activation on R-R interval and blood pressure control at high altitude. We measured the low-frequency (LF) and high-frequency (HF) components in R-R, non-invasive blood pressure and skin blood flow, and the effect of baroreceptor modulation by 0. 1-Hz sinusoidal neck suction. Ten healthy sea-level natives and three high-altitude native, long-term sea-level residents were evaluated at sea level, upon arrival at 4970 m and 1 week later.2. Compared with sea level, acute high altitude decreased R-R and increased blood pressure in all subjects [sea-level natives: R-R from 1002+/-45 to 775+/-57 ms, systolic blood pressure from 130+/-3 to 150+/-8 mmHg; high-altitude natives: R-R from 809+/-116 to 749+/-47 ms, systolic blood pressure from 110+/-12 to 125+/-11 mmHg (P<0.05 for all)]. One week later systolic blood pressure was similar to values at sea level in all subjects, whereas R-R remained elevated in sea-level natives. The low-frequency power in R-R and systolic blood pressure increased in sea-level natives [R-R-LF from 47+/-8 to 65+/-10% (P<0.05), systolic blood pressure-LF from 1.7+/-0. 3 to 2.6+/-0.4 ln-mmHg2 (P<0.05)], but not in high-altitude natives (R-R-LF from 32+/-13 to 38+/-19%, systolic blood pressure-LF from 1. 9+/-0.5 to 1.7+/-0.8 ln-mmHg2). The R-R-HF decreased in sea-level natives but not in high-altitude natives, and no changes occurred in systolic blood pressure-HF. These changes remained evident 1 week later. Skin blood flow variability and its spectral components decreased markedly at high altitude in sea-level natives but showed no changes in high-altitude natives. Neck suction significantly increased the R-R- and systolic blood pressure-LF in all subjects at both sea level and high altitude.3. High altitude induces sympathetic activation in sea-level natives which is partially counteracted by active baroreflex. Despite long-term acclimatization at sea level, high-altitude natives also maintain active baroreflex at high altitude but with lower sympathetic activation, indicating a persisting high-altitude adaptation which may be genetic or due to baroreflex activity not completely lost by at least 1 year's sea-level residence.

Adult↗
PubMed1998

Hypoxic ventilatory responses and gas exchange in patients with Parkinson's disease.

Ventilatory responses to isocapnic, progressive hypoxic rebreathing (HVR), in supine and sitting positions, lung ventilation and gas exchange while breathing air and during 5 min of breathing 11% O2 in N2 were studied in 12 healthy young (20-28 years), 5 old (57-73 years) male subjects, and in 7 male patients with Parkinson's disease (PD) aged 55-67 years. The piecewise linear approximation technique was used for evaluation of the ventilatory response curves, which allowed a separate analysis of slopes during minor and severe hypoxia. It has been shown that body position affected HVR. In the range of PETO2 from 60 to 35 mm Hg, the ventilatory response in the sitting position was higher than supine: in young persons by 43%, in healthy old persons by 76%, and in the PD patients by 211%. No significant differences in HVR to minor hypoxia (PETO2 from 100 to 60 mm Hg) were found in the 3 groups. During severe hypoxia (PETO2 from 60 to 35 mm Hg) the slope of minute ventilation versus O2 was 4.6 (supine) and 2.6 (sitting) times greater in healthy old men than PD patients' slopes. PD patients compared to old controls had 32% lower alveolar ventilation, 10% lower PETO2 and 15% elevation of PETCO2 while breathing air; similar differences were found while the patients were breathing 11% O2. The reduced alveolar ventilation under severe hypoxia in patients with PD could not be attributed to mechanical restriction of lung function. We suggest that the discrepancy in HVR under minor and severe hypoxia results from dysfunction in chemoreception associated with Parkinsonism.

Adaptation, Physiological↗