Biomedical subjects

L G Moore

Publications and source records attributed to L G Moore.

At least 73 records · Page 4Linked to original sources

PubMed1995

Effects of ovariectomy and FecBB genotype on the median charge and circulating half-life of pituitary FSH isoforms of ewes.

This study investigated the effects of short-term (20 days) ovariectomy, the effects of FSH assay (radioimmunoassay, receptor assay or in vitro bioassay) and of FecBB genotype on the characteristics of pituitary FSH from Booroola ewes. Pituitary extracts were obtained from ovariectomized homozygous carriers (BB) and non-carriers (++, n = 8 per genotype) and ovary-intact controls (n = 4 per genotype). The extracts (n = 4 per genotype per treatment) were subjected to agarose suspension electrophoresis and the eluates were assayed by the three FSH methods. There were significant effects of ovariectomy (P < 0.01) and assay system (P < 0.05) but not of genotype on the median charge of FSH isoforms. The mean +/- SEM migration rates for FSH in intact and ovariectomized ewes were 0.469 +/- 0.006 and 0.439 +/- 0.006 albumin mobility units, respectively (P < 0.01), indicating a shift to more basic isoforms after short-term ovariectomy. When the pituitary extracts were subjected to anion-exchange HPLC, there was a significant (P < 0.01) shift to more basic isoforms in the ovariectomized ewes as shown using agarose electrophoresis, and no gene effects were noted. When the pituitary extracts (n = 4-8 per group) were injected into mature female mice, there were no significant effects of ovariectomy or genotype on the circulating half-lives of the pituitary FSH isoforms. These results indicate that after short-term ovariectomy, the increase in plasma FSH concentrations is accompanied by a shift in the median charge of pituitary FSH isoforms without any observable change in their metabolic clearance rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Induction of an acute phase response in lambs causes an increase in plasma levels of GH and IGF-I.

GH and IGF-I plasma concentrations were measured in lambs during an acute phase response induced by an intrathoracic injection of yeast. The acute phase response was indicated by reduced feed intake, weight loss and an increase in plasma concentrations of the acute phase protein haptoglobin. Intensive blood sampling on day 1 revealed elevated basal concentrations of GH in the yeast-injected group compared with concentrations in pair weight and ad libitum fed control lambs. This suggests that at the beginning of an acute phase response there is an increase in either GH secretion or the half life of GH. No evidence of a specific GH-binding protein in sheep plasma could be detected. IGF-I concentrations in the yeast-injected group remained constant for 3 days then increased to a peak level at day 6. In contrast, plasma IGF-I concentrations were depressed from days 3 to 6 in the pair weight control group and they were unchanged in the ad libitum fed controls. When the IGF-I concentrations were elevated in the yeast-injected group, this group had a higher daily weight gain despite their lower feed intake compared with the ad libitum fed controls. These results suggest that IGF-I may be associated with the increase in weight in the late stage of an acute phase response during recovery from an infection or injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute-Phase Reaction↗

PubMed1995

IGF feedback effects on growth hormone secretion in ewes: evidence for action at the pituitary but not the hypothalamic level.

The putative negative feedback effects of IGF-I and IGF-II on GH secretion were tested by intracerebroventricular (icv) and intrapituitary administration to sheep. Over two consecutive days, serial jugular blood samples were taken at 10 min intervals for 6 h from ewes (n = 3/group) fitted with indwelling stainless steel cannulae into the lateral or third cerebral ventricles. The sheep were injected (icv) with either vehicle or purified ovine IGF-I (2, 4 or 8 micrograms). IGF-I injection had no effect on plasma GH secretion. Serial blood samples were taken from a second group of nine ewes in which ovine or recombinant human (rh) IGF-I was infused (2.5 micrograms/h for 2 h) into the third ventricle; once again, IGF-I failed to affect the episodic pattern of GH secretion. Three ewes fitted with indwelling stainless steel cannulae placed in the anterior pituitary gland were consecutively infused with either ovine or rhIGF-I (2.5 micrograms/h for 2 h) or vehicle. Plasma GH concentrations were suppressed in 3/3 sheep from 1-1.5 h after the commencement of infusion and GH levels remained low for the remainder of the sampling period. In another group of five ewes synergistic effects of IGF-I and IGF-II on GH secretion were tested by icv infusion of rhIGF-I, rhIGF-II, or rhIGF-I+rhIGF-II (5 micrograms/h for 2 h) or vehicle (sterile 10 mM HCl/saline). Each sheep received each treatment in a randomised design. Infusion (icv) of IGF-I and IGF-II alone or in combination failed to alter GH secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Pituitary and plasma levels of growth hormone in Booroola sheep that are either homozygous carriers or non-carriers of the FecBB fecundity gene.

The aim of this study was to examine the effect of the FecBB fecundity gene on plasma concentrations and pituitary content of growth hormone (GH) in sheep. No differences were found between homozygous carriers (BB) and non carriers (++) of the FecBB gene with regard to pituitary GH contents in both ovariectomized and intact ewes. However, ovariectomized ewes had higher levels of pituitary GH than intact ewes (P < 0.01). There were no differences between FecBB genotypes with respect to plasma concentrations of GH in 6-year-old ovariectomized ewes bled every 10 min for 12 h or in ram lambs bled weekly during their first year of life. GH levels in the rams decreased until week 27, increased to a peak at week 31 then decreased before increasing again at week 43. Mean plasma GH concentrations in the ewe lambs bled weekly for a year decreased until week 19 then remained at approximately this level for the remainder of the year. Mean GH plasma concentrations in the ram lambs were higher than in the ewe lambs (P < 0.001). Ewe lambs that were homozygous for the FecBB gene had lower body weights (P < 0.05) and had higher levels of GH (P < 0.01) than non carrier ewe lambs during their first year. Before the average age of first behavioural oestrus (36 weeks) GH levels in the ewe lambs were negatively correlated with body weights (r = -0.69, P < 0.001, n = 22). When body weight was included as a covariate in analysis of variance the genotype difference in ewe lamb plasma GH concentrations was no longer significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1994

Mitochondrial DNA analysis in Tibet: implications for the origin of the Tibetan population and its adaptation to high altitude.

Mitochondrial DNAs (mtDNAs) of 54 Tibetans residing at altitudes ranging from 3,000-4,500 m were amplified by polymerase chain reaction (PCR), examined by high-resolution restriction endonuclease analysis, and compared with those previously described in 10 other Asian and Siberian populations. This comparison revealed that more than 50% of Asian mtDNAs belong to a unique mtDNA lineage which is found only among Mongoloids, suggesting that this lineage most likely originated in Asia at an early stage of the human colonization of that continent. Within the Tibetan mtDNAs, sets of additional linked polymorphic sites defined seven minor lineages of related mtDNA haplotypes (haplogroups). The frequency and distribution of these haplogroups in modern Asian populations are supportive of previous genetic evidence that Tibetans, although located in southern Asia, share common ancestral origins with northern Mongoloid populations. This analysis of Tibetan mtDNAs also suggests that mtDNA mutations are unlikely to play a major role in the adaptation of Tibetans to high altitudes.

Adaptation, Physiological↗

PubMed1994

Oxfendazole treatment of non-parasitized lambs and its effect on the immune system.

Ten parasite-free lambs were drenched with oxfendazole on days 0 and 28 and, one day after each drench, were injected with human erythrocytes and ovalbumin. Ten other antigen-injected lambs were not drenched (controls). Lymphocytes collected 3 days after each antigen injection and cultured in RPMI 1640 plus 5% fetal calf serum (FCS) and lymphocytes collected 3 days after the first and 3 and 7 days after the second antigen injection and cultured in 50% autologous serum had decreased blastogenic activity compared with control lymphocytes. After the second drench, decreased blastogenesis was seen with lymphocytes collected on days 3 and 7 and cultured in 5% FCS and concanavalin A (Con A) and on day 3 when cultured in 5% FCS and phytohaemagglutinin (PHA). Decreased blastogenesis was also seen with lymphocytes collected 7 and 29 days after the second injection of antigen and cultured in 50% autologous serum plus Con A and on days 3, 7 and 29 when cultured in 50% autologous serum and PHA. Significantly depressed antibody responses to both antigens were seen after the second drench. The serum complement level was depressed 3 days after the second injection of antigen. Serum nitric oxide levels were significantly depressed 3 and 21 days after the first and 7 and 21 days after the second injection of antigen. There were no differences in levels of growth-promoting hormones but the drenched lambs gained significantly more weight than the controls.

Animals↗

PubMed1994

Fenbendazole and its effect on the immune system of the sheep.

Ten parasite-free 6-month-old lambs were drenched on days 0 and 28 with fenbendazole and 1 day after each drench were injected with human erythrocytes and ovalbumin. Ten other lambs injected with the antigens were not drenched with anthelmintic and served as controls. Lymphocytes from the fenbendazole-drenched lambs collected 3 days after the first antigen injections and cultured in vitro in RPM1 1640 plus 5% foetal calf serum, and lymphocytes collected at 3 and 7 days and cultured in RPM1 plus 50% autologous serum, had decreased blastogenic activity compared with lymphocytes from control lambs. Similarly, decreased blastogenesis was observed with lymphocytes collected 7 days after the second antigen injections from drenched lambs and cultured in 50% autologous serum containing concanavalin A. In contrast, increased blastogenesis was seen with lymphocytes collected 14 days after the second antigen injections from the drenched lambs and cultured in 50% autologous serum containing phytohaemagglutinin. Similar antibody responses were seen for the drenched and control lambs in response to the injections of both antigens except that, after the second injection, there was a significant reduction in antibody response to human erythrocytes in the fenbendazole-treated lambs. Decreased serum complement levels were seen particularly 3 and 7 days after the second antigen injections in drenched lambs. These serum samples had increased conglutinin activity. At the end of the experiment, the fenbendazole-drenched lambs were significantly heavier than the control lambs. However, this did not appear to be related to any effects of fenbendazole on levels of growth promoting hormones.

Journal Article↗

PubMed1994

Effects of testosterone on hypoxic ventilatory and carotid body neural responsiveness.

Hypoxic (HVR) and hypercapnic ventilatory responses (HCVR) are known to be influenced by the administration of testosterone, but whether the hormone acts centrally or peripherally is unknown. To determine whether testosterone alters HVR, HCVR, and carotid sinus nerve (CSN) responsiveness to hypoxia, we compared the ventilatory and CSN responses of neutered male cats treated with testosterone with those of placebo-treated cats. Testosterone treatment increased resting ventilation and CO2 production but did not change end-tidal or arterial PCO2, implying that alveolar ventilation per unit CO2 production was unaltered. Testosterone treatment raised the HVR shape parameter A value 63% in the awake animals (from 16.9 +/- 4.2 to 28 +/- 4, p < 0.05) and 69% in the anesthetized cats (from 22.4 +/- 0.9 to 37.8 +/- 3.7, p < 0.05). Testosterone also augmented the HCVR slope S in awake cats (from 0.17 +/- 0.02 to 0.25 +/- 0.04, p < 0.05). Placebo treatment did not change HVR or HCVR. The CSN response to hypoxia was greater in the testosterone-treated than in the placebo-treated animals (A = 53.6 +/- 7.1 versus 27.1 +/- 5.5 respectively, p < 0.05). The crossplot of the simultaneously measured CSN activity and ventilation during progressive hypoxia showed that the central nervous system translation of CSN output into ventilation was similar in the hormone- and placebo-treated groups. Unilateral, proximal sectioning of the CSN decreased the ventilatory and the CSN responses to hypoxia in the testosterone-treated animals but not in the placebo group. These results indicated that testosterone increased hypoxic and hypercapnic ventilatory responsiveness and increased hypoxic sensitivity of the carotid body.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Effects of close-arterial (external pudic) infusion of insulin-like growth factor-II on milk yield and mammary blood flow in lactating goats.

Five lactating goats were infused, via an external pudic arterial catheter, directly into the mammary gland with 0.9% (w/v) NaCl (20 ml/h), recombinant human insulin-like growth factor-I (IGF-I; 80 nmol/h), recombinant human IGF-II (133 nmol/h) or IGF-I and IGF-II combined. The infusion was for 6 h and milk yield was determined every 2 h. The ratio of milk yield in the infused relative to the non-infused gland was changed only slightly by saline (2%), but increased to 9% (P < 0.05) in response to IGF-I and 8% (P < 0.05) in response to IGF-II. When combined, both peptides increased this ratio by 6%. These effects were elicited within 2-4 h of the beginning of infusion. Mammary blood flow increased 50-80% (P < 0.05) during all IGF infusions, but only 28% during saline treatment. Plasma insulin decreased 50% (P < 0.01) during the infusion of IGF-I alone or in combination with IGF-II and 25% in response to IGF-II alone. Whereas plasma glucose increased by approximately 10% during infusion of IGF-I alone or with IGF-II, it was not altered by infusion of IGF-II only. The rapidity and unilateral nature of the milk-yield response to IGF-I and IGF-II is consistent with their acting directly on mammary tissue itself. Thus, the present results demonstrate similar local and systemic actions induced by intramammary infusion of IGF-II and IGF-I, although the magnitude of the response to IGF-II tends to be less than that to IGF-I.

Animals↗

PubMed1994

HIV-related deaths from selected infectious diseases among persons without AIDS in New Jersey.

This study sought to quantify HIV-related deaths among persons not classified as having AIDS, in an area where AIDS incidence among injecting drug users (IDUs) is high. Death certificates of persons who were aged 25-44 years at death, died in 1987 in two New Jersey counties, and had certain infectious conditions were compared with names in the AIDS Registry. Hospital and/or Medical Examiner records were reviewed for nonmatching cases. Cases were considered as confirmed HIV infection if there was laboratory evidence of such infection and as suggestive HIV infection if the decedent had oral thrush or a combination of certain other clinical findings were present. Of 412 deaths meeting the above criteria, 165 (40.0%) were in the AIDS Registry. We investigated 205 of the remainder; of these, 7.3% were found to have AIDS, 21.5% had confirmed HIV infection without AIDS, and 15.1% had suggestive HIV infection. This increased the HIV-related mortality in excess of deaths due to AIDS in this age group by 9.2% for confirmed HIV infections and 15.6% for both confirmed and suggestive HIV infections, with deaths among IDUs increasing 12.3% for confirmed HIV infections and 18.9% for both confirmed and suggestive HIV infections. Thus, in addition to AIDS indicator diseases, a variety of other infectious conditions can lead to death in HIV-infected persons, particularly in IDUs; however, the extent of such deaths may be less than previously described.

Adult↗

PubMed1993

Acute mountain sickness in a general tourist population at moderate altitudes.

OBJECTIVE: To determine the incidence of acute mountain sickness in a general population of visitors to moderate elevations, the characteristics associated with it, and its effect on physical activity. DESIGN: A cross-sectional study. SETTING: Resort communities located at 6300 to 9700 feet elevation in the Rocky Mountains of Colorado. PARTICIPANTS: Convenience sample of 3158 adult travelers, 16 to 87 years old (mean age [+/- SD], 43.8 +/- 11.8 years). RESULTS: Twenty-five percent of the travelers to moderate elevations developed acute mountain sickness, which occurred in 65% of travelers within the first 12 hours of arrival. Fifty-six percent of those with symptoms reduced their physical activity. The odds favoring acute mountain sickness were 3.5 times as large for visitors whose permanent residence was below 3000 feet elevation as for those whose residence was above 3000 feet; 2.8 times as large for visitors with previous symptoms of acute mountain sickness; and twice as large in travelers younger than 60 years. Women, obese persons, those in poor or average physical condition, and those with underlying lung disease also had a higher occurrence of acute mountain sickness (P < 0.05). CONCLUSIONS: Acute mountain sickness occurs in 25% of visitors to moderate altitudes and affects activity in most symptomatic visitors. Persons who are younger, less physically fit, live at sea level, have a history of acute mountain sickness, or have underlying lung problems more often develop these symptoms.

Acute Disease↗

PubMed1993

Acute mountain sickness in children at 2835 meters.

OBJECTIVE: Acute mountain sickness has been described in adults but little is known concerning its occurrence in children. Our objective was to determine the incidence of acute mountain sickness in children. METHODS: A survey questionnaire was completed by 558 children (aged 9 to 14 years) after they ascended from 1600 to 2835 m and from 405 similarly aged children after travel at sea level. RESULTS: Three or more of the following symptoms in the high-altitude setting were considered as the case definition of acute mountain sickness: headache, loss of appetite, vomiting, fatigue, insomnia, shortness of breath, and dizziness. One hundred fifty-six (28%) of the children at 2835 m developed acute mountain sickness. Three or more symptoms developed in a smaller, but nonetheless considerable, number (86 [21%]) of children at sea level. Headache, shortness of breath, and dizziness were reported more frequently at high altitude than at low altitude, whereas the other symptoms occurred with equal frequency at the two locations. CONCLUSIONS: More than one fourth of the children visiting high altitude developed acute mountain sickness. A high proportion (21%) of children at sea level developed similar symptoms, suggesting that an appreciable portion of the symptoms present were due to factors other than altitude, such as travel, anxiety, or disruption of daily routine.

Adolescent↗

PubMed1993

Protection from intrauterine growth retardation in Tibetans at high altitude.

Intrauterine growth retardation has long been recognized at high altitude. Since growth-retarded babies have a decreased chance of survival, intrauterine growth retardation would be expected to have been selected against in populations long resident at high altitude. We have previously reported that Tibetan babies born at 3,658 m weighed more than their North or South American altitude counterparts. This study sought to determine whether Tibetans were protected from altitude-associated intrauterine growth retardation. We compared birth weights in Tibetans living at low altitude in Kathmandu, Nepal (elevation 1,200 m), or at high altitude in Lhasa, Tibet Autonomous Region, China (elevation 3,658 m). Birth weights were similar in 45 low-altitude and 34 high-altitude Tibetan births regardless of whether all infants or only full-term births were considered, or whether birth weight was adjusted for variation in maternal parity, gestational age, and infant sex. In comparison with literature observations, the altitude-associated difference in birth weight was smallest in Tibetans, intermediate in South America, and greatest in North America. These data support the hypothesis that Tibetans are protected from altitude-associated intrauterine growth retardation and suggest that selection for optimization of birth weight at high altitude has occurred in Tibetans.

Adult↗

PubMed1993

Isolation and sequencing of deer and sheep insulin-like growth factors-I and -II.

We have developed a simple method for the isolation of highly purified cervine (c) and ovine (o) insulin-like growth factors-I (IGF-I) and -II. The IGFs were isolated from acidified serum by cation exchange chromatography and then purified by gel filtration, chromatofocusing, and reverse-phase chromatography. The IGF preparations are > 95% pure. The cIGF-I preparation contains < 0.056% cIGF-II and the oIGF-I preparation contains < 0.01% oIGF-II. Both the IGF-II preparations contain < 0.01% IGF-I. The amino acid sequence of cIGF-I has two differences when compared with human (h) IGF-I. The cIGF-II sequence, which is identical to bovine IGF-II, has three differences when compared with hIGF-II.

Amino Acid Sequence↗

PubMed1993

Arterial oxygenation and pulmonary arterial pressure in healthy neonates and infants at high altitude.

We sought to document arterial oxygen saturation relative to changes in the right ventricular pressure/left ventricular pressure ratio (RVP/LVP ratio), an index of pulmonary arterial pressure, in infants born at high altitude. We performed pulse oximetry and echocardiography in 15 healthy infants born in Leadville, Colo. (3100 m), at 6 to 24 hours, 24 to 48 hours, 1 week, 2 months, and 4 months of age. Pulse oximetry was done under conditions of wakefulness, feeding, and active and quiet sleep. All infants received supplemental O2 at delivery and during postnatal transition; all oximetry measurements were performed with infants breathing room air. The mean arterial O2 saturation ranged from 80.6% +/- 5.3% to 91.1% +/- 1.7% during the 4 months. Values fell during the first week after birth and then rose gradually to attain near-birth values at 2 and 4 months of age. Arterial O2 saturation was uniform among behavioral states at 6 to 24 hours and 24 to 48 hours of age. After 1 week of age, values were highest during wakefulness, intermediate during feeding and active sleep, and lowest during quiet sleep. The RVP/LVP ratio remained in the normal or mildly elevated range throughout the study period. We conclude that the RVP/LVP ratio promptly becomes normal at high altitude, and despite low arterial O2 saturation in the first weeks to months after birth, healthy newborn infants at 3100 m show little evidence of acute pulmonary hypertension.

Age Factors↗

PubMed1993

Hypoxic ventilatory responsiveness in Tibetan compared with Han residents of 3,658 m.

Lifelong high-altitude residents of North and South America acquire blunted hypoxic ventilatory responses and exhibit decreased ventilation compared with acclimatized newcomers. The ventilatory characteristics of Himalayan high-altitude residents are of interest in the light of their reportedly lower hemoglobin levels and legendary exercise performance. Until recently, Sherpas have been the only Himalayan population available for study. To determine whether Tibetans exhibited levels of ventilation and hypoxic ventilatory drives that were as great as acclimatized newcomers, we compared 27 lifelong Tibetan residents of Lhasa, Tibet, China (3,658 m) with 30 acclimatized Han ("Chinese") newcomers matched for age, body size, and extent of exercise training. During room air breathing, minute ventilation was greater in the Tibetan than in the Han young men because of an increased respiratory frequency, but arterial O2 saturation and end-tidal PCO2 did not differ, indicating similar levels of effective alveolar ventilation. The Tibetan subjects had higher hypoxic ventilatory response shape parameter A values and hypercapnic ventilatory responsiveness than the Han subjects. Among the Han subjects, duration of high-altitude residence correlated with the degree of blunting of the hypoxic ventilatory drive. Paradoxically, hyperoxia (inspired O2 fraction 0.70) increased minute ventilation and decreased end-tidal PCO2 in the Tibetan but not in the Han men. We concluded that lifelong Tibetan residents of high altitude neither hypoventilated nor exhibited blunted hypoxic ventilatory responses compared with acclimatized Han newcomers, suggesting that the effects of lifelong high-altitude residence on ventilation and ventilatory response to hypoxia differ in Tibetan compared with other high-altitude populations.

Adult↗

PubMed1993

Minimal hypoxic pulmonary hypertension in normal Tibetans at 3,658 m.

Elevated pulmonary arterial pressure in high-altitude residents may be a maladaptive response to chronic hypoxia. If so, well-adapted populations would be expected to have pulmonary arterial pressures that are similar to sea-level values. Five normal male 22-yr-old lifelong residents of > or = 3,600 m who were of Tibetan descent were studied in Lhasa (3,658 m) at rest and during near-maximal upright ergometer exercise. We found that resting mean pulmonary arterial pressure [15 +/- 1 (SE) mmHg] and pulmonary vascular resistance (1.8 +/- 0.2 Wood units) were within sea-level norms and were little changed while subjects breathed a hypoxic gas mixture [arterial O2 pressure (PaO2) = 36 +/- 2 Torr]. Near-maximal exercise [87 +/- 13% maximal O2 uptake (VO2max)] increased cardiac output more than threefold to values of 18.3 +/- 1.2 l/min but did not elevate pulmonary vascular resistance. Breathing 100% O2 during near-maximal exercise did not reduce pulmonary arterial pressure or vascular resistance. We concluded that this small sample of healthy Tibetans with lifelong residence > or = 3,658 m had resting pulmonary arterial pressures that were normal by sea-level standards and exhibited minimal hypoxic pulmonary vasoconstriction, both at rest and during exercise. These findings are consistent with remarkable cardiac performance and high-altitude adaptation.

Adult↗

PubMed1993

Sea-level PCO2 relates to ventilatory acclimatization at 4,300 m.

There is considerable variation among individuals in the extent of, and the time required for, ventilatory acclimatization to altitude. Factors related to this variation are unclear. The present study tested whether interindividual variation in preascent ventilation or magnitude of hypoxic ventilatory response related to ventilatory acclimatization to altitude. Measurements in 37 healthy resting male subjects at sea level indicated a wide range (34-48 Torr) of end-tidal PCO2 values. When these subjects were taken to Pikes Peak, CO (4,300 m, barometric pressure 462 mmHg), the end-tidal PCO2 values measured on arrival and repeatedly over 19 days were correlated with the sea-level end-tidal PCO2. At 4,300 m, subjects with high end-tidal PCO2 had low values of arterial oxygen saturation (SaO2). Also, sea-level end-tidal PCO2 related to SaO2 after 19 days at 4,300 m. Twenty-six of the subjects had measurements of isocapnic hypoxic ventilatory response (HVR) at sea level. The end-tidal PCO2 values on arrival and after 19 days residence at 4,300 m were inversely related to the sea-level HVR values. Thus both the PCO2 and the HVR as measured at sea level related to the extent of subsequent ventilatory acclimatization (decrease in end-tidal PCO2) and the level of oxygenation at altitude. The finding in our cohort of subjects that sea-level end-tidal PCO2 was inversely related to HVR raised the possibility that among individuals the magnitude of the hypoxic drive to breathe influenced the amount of ventilation at all altitudes, including sea level.

Acclimatization↗