Meeting Abstract

P1.55  Friday, Jan. 4  Metabolic rates and phenotypic flexibility in indigenous populations of the Upper Rio Negro, Amazon, Brazil BICUDO, J.E.; University of São Paulo jebicudo@ib.usp.br

Energy restriction leads to reduction in energy expenditure to maintain proper energy homeostasis. A change in the energy metabolism of the individual may be an important component of this adaptive response. Indigenous people living in the upper Amazon, Brazil, have been exposed to chronic parasite infestations. Children growth is severely impaired, and adults show reduced body mass, imbalance in body composition and low stature. These are not linked to shortage of food or poor quality diet. Rather, it is the outcome of chronic parasite infestations. The parasites compete for the energy resources available. I propose that survival of these populations has been facilitated due to phenotypic flexibility. Measurements of the Indian subjects (experimental) were taken in the field. Oxygen uptake to estimate basal metabolic rate (BMR) and peak metabolic rate (PMR) was determined by collecting respiratory expired air in a Douglas bag, which was then connected to an open flow system for O2 and CO2 analysis. To estimate BMR, samples were taken throughout the night, with the individuals laying in their hammocks. The same procedures were applied to the control group (a sample of the Brazilian standard population). To estimate PMR, individuals (experimental and controls) pedaled on a cycle ergometer until reaching a plateau. The experimental group BMR was statistically different and four times lower than the control group BMR. The PMR of both experimental and control groups were not statistically different. I hypothesize that the indigenous people may save available energy resources by lowering their BMR, but are able to work as hard as the controls when challenged, as shown by their equal PMRs. It seems that a larger metabolic scope of the indigenous people give them some advantage to cope with the parasites.