Effect of Light and Darkness on Packed Cell Volume in the Rat

Abstract

The aim of the study is to identify and characterize the circadian oscillation of Packed Cell Volume (PCV) within a 24-hour time frame in adult Sprague-Dawley rats. 56 adult Sprague-Dawley rats consists of 28 male and 28 female rats were used. Male animals weighed 150-170g while the females weighed 130140g. The animals were divided into two groups. The first group had tail-blood sampling commenced at 0600h while the second group had sampling commenced at 1800h. In each case, samples were assessed at 4 six-hourly intervals within a 24-hour time frame. PCV was determined using a standard laboratory method for haematocrit estimation. Results of the experiment did not show any sexual dimorphism between the peak and nadir of the circadian variation of PCV in male and female rats. A peak value was observed at 0600h and a nadir at 1200h in both sexes. The peak and nadir PCV values were significantly different (P < 0.05). We conclude that PCV exhibits rhythmic variations in Sprague-Dawley rats.


KEY WORDS: PCV, Circadian rhythm, Oscillation, Pineal gland, Melatonin.


[Nig. Jnl Health & Biomedical Sciences Vol.1(2) 2002: 82-85]