The acute hypoxic ventilatory response: testing the adaptive significance in human populations.

Journal Article

The acute Hypoxic Ventilatory Response (HVR) is an important component of human hypoxia tolerance, hence presumably physiological adaptation to high altitude. We measured the isocapnic HVR (L min(-1) %(-1)) in two genetically divergent low altitude southern African populations. The HVR does not differ between African Xhosas (X) and Caucasians (C) (X:-0.34+/-0.36; C:-0.42+/-0.33; P > 0.34), but breathing patterns do. Among all Xhosa subjects, size-independent tidal volume was smaller (X: 0.75+/-0.20; C: 1.11+/-0.32 L; P < 0.01), breathing frequency higher (X: 22.2+/-5.7; C: 14.3+/-4.2 breaths min(-1); P < 0.01) and hypoxic oxygen saturation lower than among Caucasians (X: 78.4+/-4.7%; C: 81.7+/-4.7%; P < 0.05). The results remained significant if subjects from Xhosa and Caucasian groups were matched for gender, body mass index and menstrual cycle phase in the case of females. The latter also employed distinct breathing patterns between populations in normoxia. High repeatability (intra-class correlation coefficient) of the HVR in both populations (0.77-0.87) demonstrates that one of the prerequisites for natural selection, consistent between-individual variation, is met. Finally, we explore possible relationships between inter-population genetic distances and HVR differences among Xhosa, European, Aymara Amerindians, Tibetan and Chinese populations. Inter-population differences in the HVR are not attributable to genetic distance (Mantel Z-test, P = 0.59). The results of this study add novel support for the hypothesis that differences in the HVR, should they be found between other human populations, may reflect adaptation to hypoxia rather than genetic divergence through time.

Full Text

Duke Authors

Cited Authors

  • Terblanche, JS; Tolley, KA; Fahlman, A; Myburgh, KH; Jackson, S

Published Date

  • March 2005

Published In

Volume / Issue

  • 140 / 3

Start / End Page

  • 349 - 362

PubMed ID

  • 15792601

Pubmed Central ID

  • 15792601

Electronic International Standard Serial Number (EISSN)

  • 1531-4332

International Standard Serial Number (ISSN)

  • 1095-6433

Digital Object Identifier (DOI)

  • 10.1016/j.cbpb.2005.01.016

Language

  • eng