1. Health Centre, 32 300 Gornji Milanovac, Serbia
2. Department of Physiology, Faculty of Medicine, University of Kragujevac, 34 000 Kragujevac, Serbia
3. Institute of Physiology “Richard Burian”, School of Medicine, University of Belgrade, 11 000 Belgrade, Serbia
4. University Hospital Centre “Kragujevac” and Faculty of Medicine, University of Kragujevac, 34 000 Kragujevac, Serbia