The role of the sodium pump in the developmental regulation of membrane electrical properties of cerebellar Purkinje neurons of the rat

The postnatal development of the rat cerebellum has been well described mor phologically and functionally. However, information regarding the electrica l characteristics of Purkinje neurons during development is sparse. Using s tandard intracellular recording, the basic electrical properties of Purkinj e neurons in cerebellar slices were compared at different postnatal ages. T here was a significant, progressive increase in the resting membrane potent ial (RMP) of Purkinje neurons with age as well as a small but significant d ecrease in the cellular input resistance (Rin). The cardiac glycoside, ouab ain (1 mM), an inhibitor of the sodium pump, depolarized Purkinje neurons s ignificantly more with age. The magnitude of the increase in depolarizing a ctivity of ouabain was equivalent to the magnitude of the increase in membr ane potential. The number of ouabain binding sites was also found to increa se with age suggesting an age related increase in the number of sodium pump sites. These results suggest that the predominant cellular mechanism which underlies the increase in membrane potential of Purkinje neurons during de velopment is an increase in the density of Na+, K+ pump sites and in the co ntribution of the electrogenic sodium pump. (C) 1999 Elsevier Science B.V. All rights reserved.