1. Department of Physiology, Medical University of Gdansk, 80-210 Gdansk, Poland
2. Department of Biochemistry, Medical University of Gdansk, 80-210 Gdansk, Poland
3. Division of Medical Laboratory Diagnostics, Medical University of Gdansk, 80-210 Gdansk, Poland
4. Heart Science Centre, Imperial College at Harefield Hospital, Harefield UB9 6JH, UK