Living matter and evolving organisms are influenced by the Earth’s rotation and revolution around the sun with its periodicity of day/light and night/darkness, with periodic changes in the length of the daily light and dark span and with seasons

Glossary: ADH – antidiuretic hormone AVP – arginine-vasopressin, vasopressin bw – body weight Ccr – changes in glomerular filtration rate (GFR) based on endogenic creatinine clearance Cin – changes in glomerular filtration rate (GFR) based on inulin clearance ERPF – Effective renal plasma flow (ml/min/m2) EPBF – Effective renal blood flow (ml/min/m2) FF – Filtration fraction (%) GFR – Glomerular filtration rate (ml/min/m2) Posm – Plasma osmolality (mmol/kg H 2 O) Uosm – Urine osmolality (mmol/kg H 2 O) P – plasma level (mmol/l) C – clearance (ml/min/m2 or *ml/min/kg bw) F – filtered load (mmol/min/m2) TR – tubular resorption (%) U*V – excretion in urine (μmol/min/m2 or *μmol/min/kg bw) Introduction Living matter and evolving organisms are influenced by the Earth’s rotation and revolution around the sun with its periodicity of day/light and night/darkness, with periodic changes in the length of the daily light and dark span and with seasons and climatic changes. Therefore, a variety of biological variables oscillate within an organism including: behaviour, physiological functions; and, biochemical factors. If any event within a biological system recurs at approximately regular intervals, it is generally referred to as a biological rhythm. Biological rhythms affect a variety of activities, such as the sleep-wake cycle, migration behaviour (birds, fish), seasonal fattening, reproductive cycles etc. The predominant rhythms in nature are daily rhythms e.g., rest-activity, body temperature, synthesis and/or secretion of many hormones, heart and respiratory rate, blood pressure, glomerular filtration rate, renal plasma flow, electrolyte concentrations in urine etc. Studies on chronobiological aspects of physiological functions have been carried out mainly on humans and laboratory animals (Koopman et al., 1989; Refinetti and Menaker, 1992; Windle et al., 1992). Ewa Skotnicka1, Zbigniew Muszczyñski2, Wioleta Dudzinska1, Maria Suska1 1 Department of Physiology, Faculty of Life Sciences, University of Szczecin, Al. Piastow 40 B , 71-065 Szczecin, Poland 2 Department of Physiological Chemistry, Faculty of Biotechnology and Animal Breeding, University of Agriculture, ul. Doktora Judyma 6, 71-466 Szczecin, Poland