Diurnal rhythm of selected haematological values in the central and peripheral blood circulation of the rabbit

Abstract

Cyclic changes in the red cell system, suggesting the existence of a diurnal rhythm, have been found in 47 mongrel rabbits. The diurnal fluctuations occur in the blood of both peripheral and central vessels. The haemoglobin level of the blood in the marginal ear vein is significantly higher than that in the posterior vena cava. No significant differences have been found between the haematocrit value of the blood in the central vessels and that in the peripheral vessels. I. INTRODUCTIONThere are numerous examples of diurnal rhythms and seasonal cycles in the animal kingdom (Bullo ugh, 1947; K 1 e i t m a n, 1949; Ha r ker 1953; Barański, et al., 1972 a). Rhythmic changes in the function of the haemopoietic system and in the composition and picture of blood are known phenomena. Barański et al., (1972 b) showed a distinct mitotic rhythm with a peak at 8 p.m. in the haemopoietic system of guinea pigs, light being an active synchronizer of mitoses in this system. Halberg & Visscher (1950) detected that physiological eosinopenia occurs in the mouse, unexposed to stress factors, in the night. Studying the diurnal rhythm of the number of eosinophiles in man, Donato & S t r u m i a (1952) demonstrated that it attains its lowest level at noon and a peak in the night. Rhythmic diurnal changes in the number of reticulocytes and the rate of their maturation in rats were found by Goldeck & Stoffregen (1952). The highest values were recorded in the evening and a minimum in the night. This rhytm seems to be endogenous. D e 1 a n e y (1960) reported the presence of diurnal physiological fluctuations in the haemoglobin level in man. It dropped Detween 6 a.m. and 10 p.m. and rose during sleep. Fox & Laird (1970) carried out a study of changes in the haematological values in the diurnal rhythm by determining the numbers of erythrocytes and leucocytes, the haematocrit value, and the haemoglobin level in the blood from the ear vein in the rabbit. The highest haematocrit value, haemoglobin level and number of erythrocytes were found between 8 a.m. and the noon, and the lowest ones in the afternoon and evening.[113]