The role of the heart in the evolution of aerobic performance.
J Exp Biol
; 227(20)2024 Oct 15.
Article
in En
| MEDLINE
| ID: mdl-39045710
ABSTRACT
Aerobic metabolism underlies vital traits such as locomotion and thermogenesis, and aerobic capacity influences fitness in many animals. The heart is a key determinant of aerobic capacity, but the relative influence of cardiac output versus other steps in the O2 transport pathway remains contentious. In this Commentary, we consider this issue by examining the mechanistic basis for adaptive increases in aerobic capacity (thermogenic VÌO2,max; also called summit metabolism) in deer mice (Peromyscus maniculatus) native to high altitude. Thermogenic VÌO2,max is increased by acclimation to cold hypoxia (simulating high-altitude conditions), and high-altitude populations generally have greater VÌO2,max than their low-altitude counterparts. This plastic and evolved variation in VÌO2,max is associated with corresponding variation in maximal cardiac output, along with variation in other traits across the O2 pathway (e.g. arterial O2 saturation, blood haemoglobin content and O2 affinity, tissue O2 extraction, tissue oxidative capacity). By applying fundamental principles of gas exchange, we show that the relative influence of cardiac output on VÌO2,max depends on the O2 diffusing capacity of thermogenic tissues (skeletal muscles and brown adipose tissues). Functional interactions between cardiac output and blood haemoglobin content determine circulatory O2 delivery and thus affect VÌO2,max, particularly in high-altitude environments where erythropoiesis can increase haematocrit and blood viscosity. There may also be functional linkages between cardiac output and tissue O2 diffusion due to the role of blood flow in determining capillary haematocrit and red blood cell flux. Therefore, the functional interactions between cardiac output and other traits in the O2 pathway underlie the adaptive evolution of aerobic capacities.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Cardiac Output
/
Peromyscus
/
Biological Evolution
/
Heart
Limits:
Animals
Language:
En
Journal:
J Exp Biol
Year:
2024
Document type:
Article
Country of publication:
Reino Unido