Developmental maturation of K transport and Na+-K+-adenosinetriphosphatase (ATPase) function in the choroid plexus (CP) was investigated in infant rats. K fluxes (86Rb), Na+-K+-ATPase enzyme activities, and [3H]ouabain binding were measured in isolated, lateral CPs removed from anesthetized Sprague-Dawley rats of several ages ranging from 1 day to 6 wk. Morphological integrity of incubated tissue was confirmed by electron microscopy. CP epithelia accumulated K at a lower level during the 1st wk after birth (40 nmol/mg wet wt) compared with CP from rats aged 11-28 days (56 nmol/mg wet wt). However, efflux curves and efflux rate coefficients among the age groups were similar. Both Na+-K+-ATPase activity in CP tissue homogenates and [3H]ouabain binding to isolated CP began to increase between age 10 and 14 days. It is concluded that CP Na+-K+-ATPase has limited capacity in the lateral CP of neonatal rats but that this important transport function matures rapidly in the 1st 2-3 wk after birth.
- Copyright © 1989 the American Physiological Society