TEMPERATURE AND FREQUENCY OF HEART BEAT IN THE COCKROACH.

Area of Science:

• * Physiology
• * Entomology
• * Biophysics

Background:

• * The frequency of heart pulsation in insects is temperature-dependent.
• * Arrhenius kinetics describe the relationship between reaction rates and temperature.
• * The thermal constant 'micro' is used to characterize temperature dependence in biological processes.

Purpose of the Study:

• * To investigate the temperature dependence of heart pulsation in *Blatta orientalis* nymphs.
• * To determine the Arrhenius activation energy (micro) for heart rate in this species.
• * To compare the determined thermal constant with those of other arthropod activities.

Main Methods:

• * Measurement of intact heart pulsation frequency in *Blatta orientalis* nymphs across a range of temperatures.
• * Application of Arrhenius equation to analyze the temperature-heart rate relationship.
• * Calculation and comparison of the thermal characteristic constant (micro).

Main Results:

• * Heart pulsation frequency increased with temperature, consistent with Arrhenius' equation.
• * The calculated thermal constant (micro) was typically 12,500 +/- calories for temperatures between 10-38°C.
• * A critical temperature around 10°C showed a shift in the thermal characteristic to 18,100 +/- calories.

Conclusions:

• * The thermal constant for heart rate in *Blatta orientalis* nymphs is comparable to that of other arthropod activities.
• * This quantitative correspondence supports the idea that 'micro' can identify controlling physiological processes.
• * The findings suggest a conserved mechanism underlying temperature-dependent physiological rates in arthropods.