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This Article Full Text Full Text (PDF) All Versions of this Article: 92/2/427    most recent expphysiol.2006.035519v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gulli, G. Articles by Hainsworth, R. Search for Related Content PubMed PubMed Citation Articles by Gulli, G. Articles by Hainsworth, R. Related Collections Human, Environmental & Exercise

¹ Institute for Cardiovascular Research, University of Leeds, Leeds, UK ² ICORD, University of British Columbia, Vancouver, Canada ³ Department of Physiology, University of Toronto and Department of Anaesthesia, Toronto General Hospital, Ontario, Canada ⁴ Department of Neurology, Yehuleshet Higher Clinic, University of Addis Ababa, Ethiopia ⁵ Department of Medicine, University of Addis Ababa, Ethiopia ⁶ Department of Physiology, Universidad Peruana Cayetano Heredia, Lima, Peru ⁷ New Mexico Health Enhancement and Marathon Clinics (NMHEMC) Research Foundation, Albuquerque, NM, USA

This report is a comparison of orthostatic tolerance and autonomic function in three groups of high-altitude dwellers: Andeans with and without chronic mountain sickness (CMS) and healthy Ethiopians. Results are compared with those from healthy sea-level residents. The aim was to determine whether different high-altitude populations adapted differently to the prevailing hypobaric hypoxia. Orthostatic tolerance was assessed using a test involving head-up tilt (HUT) and graded lower body suction. This was performed at the subjects' resident altitude. Blood pressure (Portapres) and R–R interval (ECG) were recorded during the test, and spectral and cross-spectral analyses of heart period and systolic blood pressure time series were performed using data obtained both while supine and during HUT. The transfer function gain in the low-frequency range (LF, 0.1 Hz) at the point of maximal coherence was used as a measure of cardiac baroreflex sensitivity (BRS). As previously reported, Peruvians displayed an unusually good orthostatic tolerance, while Ethiopians showed an orthostatic tolerance comparable to that of healthy sea-level residents. There were no significant differences between groups in the supine values of the spectral analysis results. Head-up tilt induced the expected changes in Ethiopians (an increase in the LF components and a decrease in the respiratory components) but not in Andeans. Cross-spectral analysis showed abnormal results from all groups of high-altitude dwellers. These results indicate that Ethiopians, but not Peruvians, behave similarly to sea-level residents in terms of orthostatic tolerance and autonomic responses to orthostatic stress, as assessed from spectral analyses, and this indicates good adaptation to their environment. However, in all the high-altitude groups the results of cross-spectral analysis were atypical, suggesting some degree of impairment in baroreflex function.

(Received 21 August 2006; accepted after revision 15 November 2006; first published online 30 November 2006)
Corresponding author G. Gulli: Department of Neurological Sciences and Vision, Section of Physiology, University of Verona, Strada le Grazie 8, 37134 Verona, Italy. Email: giosuegulli{at}yahoo.it

This article has been cited by other articles:

				V. E. Claydon, G. Gulli, M. Slessarev, O. Appenzeller, G. Zenebe, A. Gebremedhin, and R. Hainsworth Cerebrovascular Responses to Hypoxia and Hypocapnia in Ethiopian High Altitude Dwellers Stroke, February 1, 2008; 39(2): 336 - 342. [Abstract] [Full Text] [PDF]