Abstract

The cardiac bioelectrical activity (ECG) of fish is conducted through water with a dispersal pattern that is propagated forward and downward from the ventral aspect of a fish's body.³ The electrical conductivity of water enables noninvasive detection of this ECG signal using an array of suitably oriented electrodes that are not in contact with the fish.². Heart rate can thus be monitored without the need for restraint or contact instrumentation. Heart rate power spectral analysis (HRSA) is a technique that quantifies cyclic oscillations in the cardiac inter-beat interval that are modulated by specific neural and hormonal mechanisms.¹ Beat-to-beat variations in heart rate in mammals occur at three characteristic frequency bands. The highest frequencies are associated with respiration, the middle frequencies with baroreceptor influences, and the lowest frequencies with thermoregulatory influences. HRSA quantifies the relative contribution of each f these characteristic inputs to heart rate variability, and is thereby a means of studying changes in autonomic nervous system function associated with various physiological or pharmacological manipulations to which an individual must adapt. HRSA has been used and documented as a means of studying autonomic control of cardiovascular homeostasis in mammals, including human beings, but has not been applied to fish. We have fabricated a chamber for transducing a fish's ECG and studying cardiac inter-beat variability, and will use this data recording and analysis system to evaluate autonomic nervous system responses to physiologic stress and a variety of drugs in fish.

Acknowledgements

This study was supported by funds from the Department Anatomy Physiological Sciences, and Radiology; North Carolina State University.

References

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2.  Altimiras, J. & E. Larsen. 2000. Non-invasive recording of heart rate and ventilation rate in rainbow trout during rest and swimming. Fish go wireless! Journal of Fish Biology 57: 197-209.

3.  Yoshikawa, H., Y. Ishida., Y. Yokohama, S. Ueno, & H. Mitsuda. 1988. Electrocardiograms in five bipolar leads recorded from the body surface of three fish species (Cyprinus carpio, Oreochromis niloticus, and Pagrus major) in fresh or sea-water. Comparative Biochemistry and Physiology A-Physiology 91A: 759-764.