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A PERFUSING SOLUTION FOR THE LOBSTER (HOMARUS) HEART AND THE EFFECTS OF ITS CONSTITUENT IONS ON THE HEART
1Laboratories of Physiology, Rutgers University, New Brunswick, New Jersey, and the Mount Desert Island Biological Laboratory, Salsbury Cove, Maine.
Insights
Maintaining lobster heart function requires a specific inorganic perfusing solution that closely matches the lobster
Area of Science:
- Marine Biology
- Comparative Physiology
- Invertebrate Zoology
Background:
- The physiological requirements of crustacean hearts are not fully understood.
- Maintaining isolated invertebrate organs for research necessitates precise physiological solutions.
- Lobster serum composition varies from seawater, impacting organ function.
Purpose of the Study:
- To determine the essential inorganic components and conditions for prolonged normal beating of the Homarus americanus heart.
- To establish optimal perfusate parameters for studying lobster cardiac physiology.
- To identify the effects of imbalanced solutions on heart function and response to stimuli.
Main Methods:
- Preparation of various inorganic perfusing solutions with controlled ionic concentrations, pH, and osmotic pressure.
- Perfusion of isolated Homarus americanus hearts with these solutions.
- Observation and recording of heart beating parameters (frequency, tone, amplitude) and responses to stimuli.
Main Results:
- A specific inorganic ion balance (Na, K, Ca, Mg, Cl, SO4) is critical for prolonged heart beating (over 20 hours).
- Deviations in pH (±0.2) and osmotic pressure (±15%) significantly impact heart function.
- Certain ions (Mg, SO4) can be absent for short periods.
- Specific solutions induce arrest in systole (e.g., NaCl) or diastole (e.g., CaCl2).
- Lithium, bromide, and iodide ions cannot substitute for sodium and chloride, respectively.
Conclusions:
- Prolonged, normal beating of the Homarus americanus heart requires a perfusate mirroring its serum's inorganic composition.
- Precise control of ion concentrations, pH, and osmotic pressure is vital for maintaining cardiac function.
- Understanding these ionic requirements is crucial for future research on crustacean cardiovascular physiology.
Abstract:
1. All inorganic perfusing solution for the heart of the lobster Homarus americanus, to allow prolonged normal beating (20 hours or more) must agree closely with the inorganic composition of the serum, which varies differentially with that of the environmental sea water. 2. All of the chief inorganic ions of the serum are necessary-Na, K, Ca, Mg, Cl, and SO(4); the critical numbers of the ions being 100, 3, 5, 2-3, 116, and 1-2 respectively. Absence of Mg and SO(4) will be tolerated for several hours. 3. The pH of the solution must agree with that of the serum within 0.2. 4. The osmotic pressure of the solution must agree with that of the serum within 15 per cent. 5. Beating of the heart will continue for several hours on improperly balanced solutions but changes in frequency, tone, or amplitude will occur. Hearts adapted to such solutions will show different responses to physical and chemical stimuli of the solution than those perfused on properly balanced solutions. 6. Arrest in systole is caused by isotonic NaCl, KCl, LiCl, and urea, and arrest in diastole by isotonic CaCl(2), MgCl(2), NaBr, NaI, MgSO(4), and glucose. 7. Lithium cannot replace sodium; neither can bromide or iodide replace chloride ions.
