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Cardiac performance in semi-isolated heart of the crab Carcinus maenas
1Department of Biological Sciences, University of Calgary, Alberta, Canada.
Insights
The shore crab heart preparation (Carcinus maenas) pumps effectively but lacks adaptive responses. Its performance is lower than myogenic hearts, likely due to the semi-isolated preparation lacking neural input.
Area of Science:
- Marine Biology
- Crustacean Physiology
- Cardiovascular Research
Background:
- The shore crab, Carcinus maenas, possesses a semi-isolated heart.
- Understanding its intrinsic cardiac function is crucial for comparative physiology.
Purpose of the Study:
- To characterize the performance of an in situ heart preparation of Carcinus maenas.
- To assess the heart's response to physiological challenges without neural input.
Main Methods:
- Isolated, in situ heart preparation of Carcinus maenas supported by alary ligaments.
- Measurement of heart rate, cardiac output, contractile force, stroke work, and power.
- Assessment of responses to changes in pericardial sinus pressure, outflow resistance, and afterload.
Main Results:
- The heart preparation pumped vigorously for hours with a mean heart rate of 49.7 beats/min and cardiac output of 30 ml.kg-1.min-1.
- No adaptive responses were observed to changes in pressure, resistance, or afterload.
- Perfusion-induced stretch increased contractile force but minimally affected heart rate.
- Stroke work and power were lower than in myogenic hearts with closed circulatory systems.
Conclusions:
- The semi-isolated heart preparation of Carcinus maenas exhibits intrinsic contractile capacity but limited adaptability.
- Observed lower cardiac output and heart rate compared to in vivo values may reflect the preparation's limitations and absence of neural/neurohormonal input.
- The study provides baseline data on crustacean cardiac performance in a controlled, semi-isolated setting.
Abstract:
A semi-isolated, in situ heart preparation of the shore crab, Carcinus maenas, supported by its alary ligaments, pumps vigorously for hours at a mean heart rate of 49.7 beats/min and cardiac output of 30 ml.kg-1.min-1. These hearts show no adaptive responses to changes in pericardial sinus pressure, outflow resistance, or afterload. Direct perfusion-induced stretch of the heart wall causes increases in contractile force but minimal changes in heart rate. Stroke work and power are lower than comparable values for animals with myogenic hearts and closed circulatory systems. The values for heart rate and cardiac output are lower than in vivo values and may in part reflect the technique used as well as intrinsic performance of the heart without neural and neurohormonal inputs. Morphometrically the heart represents 0.2% of whole body weight, and the mean stroke volume of 0.35-0.45 ml/kg represents an ejection fraction of 27-34% of ventricular volume (1.4 ml/kg).