Document Detail


Hypertension and counter-hypertension mechanisms in giraffes.
MedLine Citation:
PMID:  16724937     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The giraffe is unique as its head is 2500-3000 millimeters above its heart, thus the giraffe's heart must pump hard enough to overcome the huge hydrostatic pressure generated by the tall column of blood in its neck in order to provide its head with sufficient nutrients and oxygen. Giraffes therefore have exceptionally high blood pressure (hypertension) by human standards. Interestingly, the "unnaturally" high blood pressure in giraffes does not culminate in severe vascular lesions, nor does it lead to heart and kidney failure, whereas in humans, the same blood pressure is exceedingly dangerous and will cause severe vascular damage. Intrinsically, natural selection likely has provided an important protective mechanism, because hypertension develops as soon as the giraffe stands up and erects its neck immediately after birth. Therefore, those individual giraffes who did not tolerate the burden of hypertension presumably developed acute heart failure and renal failure, not surviving to reproductive age. The genes and genotypes of animals that did not survive are thus predicted to have been gradually eliminated from the gene pool by natural selection. By the same process, genes that protect against hypertensive damage would be preserved and inherited from generation to generation. Some unique ingredients of the giraffe's diet may also provide an extrinsic mechanism for the prevention of hypertension and the prevention of fatal end-stage organ damage. The fascinating nature of the protective mechanisms in giraffes may provide a conceptual framework for further experimental investigations into mechanisms as well as prevention and treatment of human hypertension and cardiovascular disease.
Authors:
Qiong Gus Zhang
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Publication Detail:
Type:  Journal Article; Review    
Journal Detail:
Title:  Cardiovascular & hematological disorders drug targets     Volume:  6     ISSN:  1871-529X     ISO Abbreviation:  -     Publication Date:  2006 Mar 
Date Detail:
Created Date:  2006-05-26     Completed Date:  2006-09-25     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101269160     Medline TA:  Cardiovasc Hematol Disord Drug Targets     Country:  United Arab Emirates    
Other Details:
Languages:  eng     Pagination:  63-7     Citation Subset:  IM    
Affiliation:
MSC789, California Institute of Technology, Pasadena, CA 91126, USA. qiong@caltech.edu
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MeSH Terms
Descriptor/Qualifier:
Anatomy, Comparative / methods
Animals
Artiodactyla / anatomy & histology,  physiology*
Blood Pressure / physiology
Blood Pressure Determination / methods
Heart / anatomy & histology,  physiology
Humans
Hypertension / physiopathology*,  prevention & control*
Kidney / anatomy & histology,  physiology
Physiology, Comparative / methods

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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