Computer Methods and Programs in Biomedicine 62 (2000) 145 – 152 Portable data acquisition system for EKG measurements in marine environments M. Rodrı ´guez a, *, A. Ayala a , F. Rosa a , F. Herrera a , S. Rodrı ´guez a , M. Dı ´az-Gonza ´lez b a Department of Fundamental and Experimental Physics, Uniersity of La Laguna, 38203 La Laguna, Tenerife, Canary Islands, Spain b Department of Animal Biology. Animal Physiology Laboratory, Uniersity of La Laguna, 38206 La Laguna, Tenerife, Canary Islands, Spain Received 1 June 1999; received in revised form 8 November 1999; accepted 5 January 2000 Abstract In the present paper, an electronic prototype designed to acquire electrocardiographic signals from marine mammals has been developed. The system consists of a portable device that allows the on-line acquisition of EKG signals through a parallel port interface that is connected to a laptop computer. The EKG waveform, the voltage level, the bandwidth and the most relevant information from this type of signals is stored and analysed under real-time conditions by means of specifically implemented software. The whole system has been successfully tested to obtain the EKG from captive dolphins. The characteristics of the equipment presented here, with its low cost, size and energy requirements accomplish a portable system suitable for the acquisition of this type of signals in conductive media such as the seawater. © 2000 Elsevier Science Ireland Ltd. All rights reserved. www.elsevier.com/locate/cmpb 1. Introduction One of the most intriguing physiological ques- tions related to life in the aquatic environment is the physiology of diving mammals. Most of our knowledge of mammalian diving comes from studies performed in the laboratory because of the ease and technical sophistication of the studies there. At present, most studies have been carried out on animals forced or trained to submerge [1,2]. Although, the techniques that could be ap- plied in the wild were much more limited than those in the laboratory, it quickly became evident that the physiology of voluntary diving differs from that of forced diving in the labora- tory. Together with the respiratory activity stop when diving mammals break contact with the atmosphere, a set of cardiovascular adaptations are triggered during diving. These include slowing of the heart rate (referred to as diving bradicar- dia), decline of the cardiac output and eventually changes in the resistance of vascular beds leading to an increased peripheral vasoconstriction. These clear adaptive responses are common and have * Corresponding author. 0169-2607/00/$ - see front matter © 2000 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 1 6 9 - 2 6 0 7 ( 0 0 ) 0 0 0 5 4 - 7