title: Rates of oxygen uptake increase independently of changes in heart rate in late stages of development and at hatching in the green iguana, Iguana iguana.
abstract: Oxygen consumption (VO2), heart rate (fH), heart mass (Mh) and body mass (Mb) were measured during embryonic incubation and in hatchlings of green iguana (Iguana iguana). Mean fHand VO2were unvarying in early stage embryos. VO2increased exponentially during the later stages of embryonic development, doubling by the end of incubation, while fHwas constant, resulting in a 2.7-fold increase in oxygen pulse. Compared to late stage embryos, the mean inactive level of VO2in hatchlings was 1.7 fold higher, while fHwas reduced by half resulting in a further 3.6 fold increase in oxygen pulse. There was an overall negative correlation between mean fHand VO2when data from hatchlings was included. Thus, predicting metabolic rate as VO2from measurements of fHis not possible in embryonic reptiles. Convective transport of oxygen to supply metabolism during embryonic incubation was more reliably indicated as an index of cardiac output (COi) derived from the product of fHand Mh. However, a thorough analysis of factors determining rates of oxygen supply during development and eclosion in reptiles will require cannulation of blood vessels that proved impossible in the present study, to determine oxygen carrying capacity by the blood and arteriovenous oxygen content difference (A-V diff), plus patterns of blood flow.
authors.affiliation: Departamento de Zoologia, Instituto de Biociências, Universidade Estadual Paulista, Campus Rio Claro, SP, 13506-900, Brazil. Electronic address: marinarsartori@gmail.com.
authors.forename: Marina R
authors.initials: MR
authors.lastname: Sartori
authors.affiliation: Departamento de Zoologia, Instituto de Biociências, Universidade Estadual Paulista, Campus Rio Claro, SP, 13506-900, Brazil.
authors.forename: Augusto S
authors.initials: AS
authors.lastname: Abe
authors.affiliation: Department of Biological Sciences, Developmental Integrative Biology Cluster, University of North Texas Denton, TX 76203-5017, USA.
authors.forename: Dane A
authors.initials: DA
authors.lastname: Crossley
authors.affiliation: Departamento de Zoologia, Instituto de Biociências, Universidade Estadual Paulista, Campus Rio Claro, SP, 13506-900, Brazil; School of Biosciences, University of Birmingham, Birmingham, B15 2TT, United Kingdom.
authors.forename: Edwin W
authors.initials: EW
authors.lastname: Taylor
mesh_terms: D000818:Animals; D001835:Body Weight; D002302:Cardiac Output; D006321:Heart / Q000033:anatomy & histology; D006339:Heart Rate; D007076:Iguanas / Q000033:anatomy & histology / Q000254:growth & development* / Q000502:physiology*; D009929:Organ Size; D010101:Oxygen Consumption
keywords: Embryo; Growth; Heart rate; Iguana; Oxygen pulse; Oxygen uptake; Reptile