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Development of potassium transport capability by choroid plexus of infant rats
1Department of Clinical Neurosciences, Brown University/Rhode Island Hospital, Providence 02903.
Insights
The choroid plexus (CP) shows limited potassium transport and Na+-K+-adenosinetriphosphatase (ATPase) function in newborn rats. This vital transport function rapidly matures within the first 2-3 weeks after birth.
Area of Science:
- Neuroscience
- Physiology
- Developmental Biology
Background:
- The choroid plexus (CP) is crucial for cerebrospinal fluid production and brain homeostasis.
- Na+-K+-adenosinetriphosphatase (ATPase) is a key ion transporter vital for cellular function.
Purpose of the Study:
- To investigate the developmental changes in potassium (K) transport and Na+-K+-ATPase activity in the infant rat choroid plexus.
- To understand the maturation process of ion transport mechanisms in the neonatal brain.
Main Methods:
- Isolated lateral choroid plexuses (CPs) from Sprague-Dawley rats aged 1 day to 6 weeks were used.
- Measurements included potassium fluxes (using 86Rb), Na+-K+-ATPase enzyme activity, and [3H]ouabain binding.
- Tissue integrity was confirmed using electron microscopy.
Main Results:
- Neonatal rat CP accumulated less potassium during the first week compared to older rats (11-28 days).
- Potassium efflux rates and coefficients remained similar across age groups.
- Na+-K+-ATPase activity and [3H]ouabain binding increased significantly between 10 and 14 days of age.
Conclusions:
- Na+-K+-ATPase function in the neonatal rat lateral CP is initially limited.
- This essential transport system undergoes rapid maturation in the early postnatal weeks.
- These findings highlight critical developmental changes in CP ion transport crucial for brain development.
Abstract:
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.