期刊
JOURNAL OF EXPERIMENTAL BIOLOGY
卷 219, 期 3, 页码 457-463出版社
COMPANY OF BIOLOGISTS LTD
DOI: 10.1242/jeb.132753
关键词
Echocardiography; Left ventricle; End diastolic volume; Cardiac output; Stroke volume
类别
资金
- Lundbeck Foundation
- Carlsbergfondet
- Danish Heart Association
- Aase and Ejnar Danielsen Foundation
- Danish Research Council
- Danish Cardiovascular Research Academy
- Nyreforeningens Forskningsfond
- Fonden til Laegevidenskabens Fremme
- Faculty of Health Science
- Faculty of Natural Sciences at Aarhus University
- Aarhus University Research Foundation
Giraffes - the tallest extant animals on Earth - are renowned for their high central arterial blood pressure, which is necessary to secure brain perfusion. Arterial pressure may exceed 300 mmHg and has historically been attributed to an exceptionally large heart. Recently, this has been refuted by several studies demonstrating that the mass of giraffe heart is similar to that of other mammals when expressed relative to body mass. It thus remains unexplained how the normal-sized giraffe heart generates such massive arterial pressures. We hypothesized that giraffe hearts have a small intraventricular cavity and a relatively thick ventricular wall, allowing for generation of high arterial pressures at normal left ventricular wall tension. In nine anaesthetized giraffes (495 +/- 38 kg), we determined in vivo ventricular dimensions using echocardiography along with intraventricular and aortic pressures to calculate left ventricular wall stress. Cardiac output was also determined by inert gas rebreathing to provide an additional and independent estimate of stroke volume. Echocardiography and inert gas-rebreathing yielded similar cardiac outputs of 16.1 +/- 2.5 and 16.4 +/- 1.4 l min(-1), respectively. End-diastolic and end-systolic volumes were 521 +/- 61 ml and 228 +/- 42 ml, respectively, yielding an ejection fraction of 56 +/- 4% and a stroke volume of 0.59 ml kg(-1). Left ventricular circumferential wall stress was 7.83 +/- 1.76 kPa. We conclude that, relative to body mass, a small left ventricular cavity and a low stroke volume characterizes the giraffe heart. The adaptations result in typical mammalian left ventricular wall tensions, but produce a lowered cardiac output.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据