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Biomedical subjects

R D Cawkwell

Publications and source records attributed to R D Cawkwell.

4 recordsLinked to original sources
PubMed1987

Choroid plexus structure and function in young rats on a high-potassium diet.

Rats, 20 days old, were fed a diet containing 20% KCl for 10 days. At 30 days these rats had lower body, brain and choroid plexus weights than matched controls and plasma [K+] was increased to 7.5 mM compared to 4.1 mM for controls. Cerebrospinal fluid (CSF) [K+] and bulk fluid secretion were not changed by the high K+ diet but there was a mild metabolic acidosis. The fourth ventricle choroid plexus was prepared for transmission electron microscopy and the structure of the epithelium analysed by quantitative stereology. The high K+ rats had a large increase in the mitochondrial volume fraction of the epithelium due to a 36% increase in individual mitochondrial volume. The high-K+ rats also had a decrease in the apical surface density of the epithelium due to a 41% decrease in the height of the microvilli. It is concluded that the increase in mitochondrial volume may provide the additional energy required for the increased transport of K+ out of the CSF in hyperkalaemia. The reduction in height of the microvilli could be a means for maintaining a normal CSF bulk secretion rate despite the increase in K+ transport required to maintain normal CSF [K+] in hyperkalaemia.

Animals↗
PubMed1987

Effect of chronic maternal hyperkalaemia on plasma, cerebrospinal fluid and brain interstitial fluid potassium in developing rats.

Plasma hyperkalaemia was induced in pregnant and lactating rats using a high potassium diet. Fetuses of high-K-diet mothers showed no increase in the potassium concentration [( K+]) of plasma, cerebrospinal fluid (CSF) and brain interstitial fluid, presumably due to placental control. Neonates from high-K-diet rats did show an increase in plasma [K+] but this increase was very small and there was no increase in CSF or interstitial fluid [K+]. Maternal milk [K+] was not affected by plasma hyperkalaemia. Weanling rats fed the high-K diet directly showed marked plasma hyperkalaemia but no increase in CSF or interstitial fluid [K+]. Thus, prior to weaning, a relatively stable plasma [K+] is maintained by maternal influence reducing the need for direct brain fluid K+ regulation.

Animals↗
PubMed1986

A morphometric analysis of the development of the fourth ventricle choroid plexus in the rat.

The choroid plexus from the rat fourth ventricle was investigated at ages from 16 days of gestation to 30 days after birth. Choroid plexus weights were measured and light and electron micrographs were analysed by quantitative stereological techniques at 4 levels of magnification. There was a 10-fold increase in plexus weight between 19 days of gestation and 30 days after birth which was largely due to an increase in epithelial weight, with little change occurring in the connective tissue core. Before birth, epithelial cell height decreased whereas between 10 and 30 days after birth cross-sectional area increased, both events being accompanied by corresponding changes in cell volume. Large intracellular stores of glycogen were present around birth, when they occupied up to 20% of the cell volume. After birth there were significant increases in apical microvillus height, the number of microvilli per cell and in the size of the mitochondria, suggesting that a large increase in choroid plexus secretory function, or the commencement of a new function, occurs after birth in the rat.

Animals↗