Cardiovascular measurements of small fish by radio-telemetry: a preliminary study

V. van Ginneken1, P. Snelderwaard1, H.P. Voss2, R. van der Linden1, D. van der Reijden1, A. Gluvers1, G. van den Thillart1 and K. Kramer2

1Institute of Evolutionary and Ecological Sciences, Integrative Zoology, van der Klaauw Laboratory, Leiden University, Leiden, The Netherlands.
2Department of Safety and Environmental Affairs, Free University, Amsterdam, The Netherlands

For research in fish biology, basic information from individual intact stress-free fish about heart rate frequency, blood pressure, stroke volume and body temperature is essential. Radio-telemetry provides an alternative means of obtaining physiological measurements from awake and freely moving animals, without introducing stress artifacts [5].

In this poster we present for the first time the implantation technique of a telemetry transmitter implanted in the peritoneal cavity of a small fish (50-60 g) which enables us to monitor heart rate (HR), electrocardiogram (ECG) and body temperature in a freely moving fish. With this technique we hope in future to clarify the process of 'metabolic depression' [2,4]. This is a survival strategy commonly applied in animal kingdom in order to slow down the ATP-flux, save energy stores and diminish end-product accumulation (e.g. lactic acid). With direct calorimetry, measuring directly the heat production of cold-blooded fish during anoxia, a 'metabolic depression' was observed in goldfish, tilapia and eel. With a customized version of the EthoVision video analysis system (Noldus Information Technology) we demonstrated that the lowering of the metabolic rate was not caused by a reduction of external activity [3]. Based on these observations, we hypothesize that the cause of the process of 'metabolic depression' can be found at the cellular level. Fifteen years ago, Coulson [1] posed his 'blood-flow' theory, which states that the cellular metabolism is primarily regulated by the blood circulation and the factors it carries (substrates and oxygen). In addition, Guppy [4] posed the hypothesis that an organism under metabolic depression loses it characteristics of multi-cellularity and obtains the characteristics of a unicellular organism. Until now those two theories were neither rejected nor confirmed. Radio-telemetry of the cardiovascular system, in combination with direct calorimetry for measuring the metabolic rate, offers the opportunity to test the two theories of Coulson [1] and Guppy [4].

Figure 1. Goldfish (Carassius auratus L.) of 50 gram with an implanted heart rate frequency transmitter (TA10ETA-F20-L20, Data Sciences International, St Paul, MN, USA) to monitor heart rate (HR), electrocardiogram (ECG) and body temperature.

References

  1. Coulson, R.A. (1986). Metabolic rate and the flow and oxygen demand in tissues in vivo and in vitro. Persp. Biol. Med., 27, 121-126.
  2. Ginneken. V.J.T. van (1996). Review: flexible metabolic depression of fish. In: Influence of Hypoxia and Acidification on the Energy Metabolism of Fish: An in vivo 31P-NMR and Calorimetric Study. Ph.D. Thesis, Leiden University, 336 pp.
  3. Ginneken, V.J.T. van; Addink, A.D.F.; van den Thillart, G.E.E.J.M.; Noldus, L.; Buma, M. (1997). Metabolic rate and level of activity deter-mined in tilapia (Oreochromis mossambi-cus Peters) by direct and indirect calori-metry and video moni-to-ring. Thermochi-mica Acta, 291, 1-13.
  4. Guppy, M.; Fuery, C.J.; Flanigan, J.E. (1994). Biochemical principles of metabolic depression. Comp. Biochem. Physiol., 109B, 175-189.
  5. Kramer, K.; Mills, P.A.; Kinter, L.B.; Brockway, B.P. (1998). The history and present status of radio-telemetry as a tool for monitoring physiological parameters in laboratory animals. Lab Animal, 27 (8), 40-46.

Poster presented at Measuring Behavior 2000, 3rd International Conference on Methods and Techniques in Behavioral Research, 15-18 August 2000, Nijmegen, The Netherlands

© 2000 Noldus Information Technology b.v.