166 The cerebellar purkinje cells activity in young and adult rats in condition of reduced blood calcium level

The inhibitory pause after climbing fiber synaptic activation of cerebellar Purkinje cells (PC) is often used as an additional criterion for electrophysiological identification of cerebellar PC. Therefore 11 is reasonable to know what relationship exists between age and full maturation of cerebellar PC in mature and immature born animals. With this aim the experiments on 4 age-groups of mature (guinea pigs) and immature (kittens) born animals was performed. The four age groups were included: newborn, two weeks, three weeks, and two months old, in both mature and immature born animals. It was shown that in newborn guinea pigs the mean simple spike (SS) discharge frequency of PC was I 1.5 f I. I imp/s and the mean duration of inhibirory pause was 38 I i 54.5 imp/s. In newborn kittens the mean SS discharge frequency was I .36 * 0.2 imp/s and the inhibitory pause was more than 1000 ms. By two months the mean discharge frequency of Purkinje cells in guinea pigs increased to 23.2 i 2.2 imp/s and the inhibitory pause decreased to 245.2 i 38.7 ms , while the same tigures in the kittens were 8.3 f 0.6 imp/s and 261.3 f 31.5 ms respectively. The same tendency towards Increasing of the PC dischage frequency in guinea pigs lasts around 3 weeks, while in kittens it takes up over two months of postnatal life. These data suggest that the increase of Purkinje cells discharge frequency both in mature and immature animals is accompanied by a proportional decrease in the duration of the inhibitory pause in cerebellar Purkinje cell activity