Related Experiment Video
Updated: Jul 11, 2026
Cardiac Stress Test Induced by Dobutamine and Monitored by Cardiac Catheterization in Mice
Published on: February 10, 2013
Effect of anemia on cardiac function, microvascular structure, and capillary hematocrit in rat hearts
K Rakusan1, N Cicutti, F Kolar
1Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, K1H 8M5 Canada. krakusan@uottawa.ca
Insights
Anemia stimulates new blood vessel growth (angiogenesis) in rat hearts, improving red blood cell flow despite reduced blood volume. This adaptation aids cardiac function under stress.
Area of Science:
- Cardiovascular Physiology
- Hematology
- Angiogenesis Research
Background:
- Anemia can impair cardiac function by reducing oxygen delivery.
- The coronary microcirculation's response to anemia, particularly angiogenesis, is not fully understood.
Purpose of the Study:
- To investigate the effects of chronic and acute anemia on coronary microcirculation in rats.
- To determine if angiogenesis occurs in the heart during anemia-induced cardiomegaly.
- To analyze red blood cell distribution and hematocrit within capillaries under anemic conditions.
Main Methods:
- Induction of chronic anemia in young male rats.
- Acute blood withdrawal to simulate hemodilution.
- Perfusion of isolated rat hearts with varying hematocrit solutions.
- Measurement of cardiac mass, ventricular pressure, capillary density, and capillary hematocrit.
Main Results:
- Chronic anemia led to increased cardiac mass (cardiomegaly) and left ventricular end-diastolic pressure.
- Despite unchanged capillary and arteriolar densities, total capillary length increased, indicating angiogenesis.
- Capillary hematocrit decreased less than systemic hematocrit in chronic anemia and was preserved during acute hemodilution.
- Isolated hearts perfused with low hematocrit solutions showed higher capillary hematocrit than perfusate hematocrit.
Conclusions:
- Evidence of angiogenesis in anemia-induced cardiomegaly in rat hearts.
- Anemia triggers adaptive changes in microvascular red blood cell spacing and hematocrit regulation.
- These microcirculatory adaptations are enhanced during acute hemodilution and in isolated perfused hearts.
Abstract:
The effect of anemia on the coronary microcirculation was studied in young male rats. Chronic anemia resulted in increased left ventricular end-diastolic pressure and decreased functional reserve. Cardiac mass in anemic animals increased by 25%. Capillary and arteriolar densities in these hearts remained unchanged, indicating angiogenesis in this experimental situation (estimated aggregate capillary length in the left ventricle of anemic hearts was 3.06 km compared with 2.35 km in control hearts). Capillary hematocrit was decreased in chronic anemia less than systemic hematocrit: from 25 to 18% in anemia versus 45 to 28% in controls. Capillary hematocrit and red blood cell spacing were also studied after acute blood withdrawal. Here, capillary hematocrit was preserved even more: 22 versus 24% in systemic hematocrit. Finally, the same was studied in isolated hearts perfused with solutions of various hematocrits. After perfusion with low-hematocrit solution (14%), the capillary hematocrit (24%) was even higher than the perfusate hematocrit! In conclusion, we found evidence of angiogenesis in cardiomegaly induced by chronic anemia. Microvascular growth was accompanied by advantageous regulation of red blood cell spacing within these vessels. This was even more pronounced during acute hemodilution and in isolated perfused hearts.
