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Published on: August 6, 2015
[Effect of perfusate ionized calcium on mechanical activity of the rat heart in deep hypothermia]
1I. P. Pavlov Institute of Physiology, Russian Acad. Sci., St. Petersburg, 199034, Nab. Makarova, 6.
Insights
The study found that higher ionized calcium concentrations increase rat heart systolic pressure and mechanical activity at normal temperatures, but decrease it at lower temperatures. Heart rate was unaffected by calcium levels.
Area of Science:
- Cardiovascular Physiology
- Ion Transport Mechanisms
Context:
- Investigating the impact of extracellular ionized calcium ([Ca2+]) and temperature on isolated rat heart function.
- Utilizing isovolumetrically contracting heart preparations with retrograde perfusion in a modified Krebs-Heseleit buffer.
Purpose:
- To determine how varying concentrations of ionized calcium and heart temperature influence systolic pressure (Psyst), heart rate (Vc), and heart mechanical activity (HMA).
Summary:
- At normothermia (38°C), increasing [Ca2+] from 0.62 to 2.5 mM augmented Psyst and HMA, with no change in Vc.
- At 20°C, elevating [Ca2+] from 0.62 to 4.5 mM increased Vc and HMA.
- At lower temperatures (11-15°C), higher [Ca2+] decreased Psyst and HMA, without affecting the heart arrest temperature.
Impact:
- Provides crucial insights into the complex interplay between calcium ions and temperature in regulating cardiac contractility and mechanical function.
- Highlights the temperature-dependent effects of calcium on cardiac performance, essential for understanding physiological and pathological conditions.
Abstract:
Effects of different concentrations of ionized calcium ([Ca2+]) in perfusion fluid and of the heart temperature on the systolic pressure (Psyst), heart rate (Vc) and their product as general index of the heart mechanical activity (HMA) of the rat isovolumetrically contracting isolated heart preparations were examined in condition of retrograde perfusion at constant volume with a modified Krebs-Heseleit buffer. An increase of [Ca2+] from 0.62 to 2.5 mM (mmol/l) in the normothermia (38 degrees C) augments Psyst and HMA. Heart rate does not change. An increase of [Ca2+] from 0.62 to 4.5 mM at 20 degrees C augments Vc and HMA. An increase [Ca2+] at 15-11 degrees C decreases psyst and HMA. [Ca2+] does not affect the temperature of the heart arrest.
