Cardiovascular responses to graded degrees of hypoxaemia in the llama fetus

Reproduction, Fertility, and Development
A J LlanosJ T Parer

Abstract

The fetal llama exposed to an intense degree of hypoxaemia did not increase cerebral blood flow, but showed a marked peripheral vasoconstriction. The same cardiovascular response is observed in fetal sheep submitted to a extremely severe hypoxaemia, when the initial compensatory vasodilatory mechanisms in brain and heart fail. To investigate whether the fetal llama responses to acute hypoxaemia are adaptive, or whether they are the result of a breakdown of mechanisms of blood flow redistribution that favours the central nervous system, we studied seven fetal llamas (0.6-0.7 of gestation) chronically-catheterized during 1 h of graded and progressive hypoxaemia. Fetal ascending aorta blood gases and fetal cardiac output and its distribution (radiolabelled-microspheres) were measured after 60 min of normoxaemia (B) and at the end of 20 min (H20), 40 min (H40) and 60 min (H60) of hypoxaemia. Data were analysed by ANOVA and Newman-Keuls tests. Each treatment resulted in a lower (P < 0.05) percentage of haemoglobin saturation than hypoxaemia; H40 was lower than H20, and H60 was lower than H20 and H40. No statistical difference was observed among treatments for cardiac output or cerebral blood flow. These results demonstrate that feta...Continue Reading

Citations

Feb 18, 1998·Brain Research. Developmental Brain Research·C E BlancoA J Llanos
Sep 15, 2000·European Journal of Obstetrics, Gynecology, and Reproductive Biology·R P SmithN M Fisk
Feb 3, 1998·European Journal of Obstetrics, Gynecology, and Reproductive Biology·M A Hanson
Oct 16, 2002·Animal Reproduction Science·Emilio A HerreraAníbal J Llanos
Jun 26, 2001·Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology·M GalleguillosA J Llanos
Jul 31, 1998·Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology·A LlanosJ Parer
Mar 20, 2001·High Altitude Medicine & Biology·E A HerreraA J Llanos
Jul 12, 2003·High Altitude Medicine & Biology·Aníbal J LlanosDino A Giussani
May 23, 2009·The Veterinary Clinics of North America. Food Animal Practice·Marco L MargioccoJohn D Bonagura
Jun 26, 2007·Respiratory Physiology & Neurobiology·Aníbal J LlanosMark A Hanson
Oct 11, 2003·BJOG : an International Journal of Obstetrics and Gynaecology·Richard P SmithNicholas M Fisk
Jun 3, 2004·Best Practice & Research. Clinical Anaesthesiology·Michelle C White, Andrew R Wolf
Oct 17, 2014·Journal of Veterinary Internal Medicine·F R BertinS D Taylor
Jul 23, 2005·The Journal of Physiology·Germán EbenspergerRoberto V Reyes
May 21, 2005·American Journal of Physiology. Regulatory, Integrative and Comparative Physiology·Emilia M SanhuezaAníbal J Llanos
Nov 19, 2011·Journal of Applied Physiology·Aníbal J LlanosDino A Giussani
Jul 25, 2020·Journal of Developmental Origins of Health and Disease·Alejandro Gonzaléz-CandiaEmilio A Herrera

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