Related Experiment Videos
Correlation of function and structure in developing rat distal colon
R Vagnerová1, L Kubínová, J Pácha
1Institute of Histology and Embryology, First Medical Faculty, Charles University, Albertov 2, Prague 2, Czech Republic.
Insights
During weaning, aldosterone induces sodium absorption in rat colons. High salt intake during this period inhibits this process and alters cell membrane development, impacting colon function.
Area of Science:
- Physiology
- Developmental Biology
- Cell Biology
Background:
- Suckling rats exhibit amiloride-sensitive sodium (Na+) absorption in the distal colon, mediated by electrogenic transport.
- This Na+ transport pathway is induced by aldosterone in superficial colonic epithelial cells and diminishes post-weaning.
Purpose of the Study:
- To investigate the relationship between distal colon function and the apical and basolateral membrane surface areas of superficial enterocytes during the weaning period.
- To understand the role of aldosterone and dietary salt intake in these developmental changes.
Main Methods:
- Comparative analysis of membrane surface densities (apical and basolateral) in enterocytes from 14-day-old and 27-day-old rats.
- Measurement of plasma aldosterone concentrations and assessment of electrogenic amiloride-sensitive Na+ transport and Na, K-ATPase activity.
- Evaluation of the effects of high dietary salt intake during weaning on these parameters.
Main Results:
- Basolateral membrane surface density increased significantly between 14 and 27 days of age, coinciding with high aldosterone levels and increased Na+ transport and Na, K-ATPase activity.
- High salt intake during weaning prevented the increase in basolateral membrane surface density, inhibited Na+ transport, and reduced aldosterone levels and Na, K-ATPase activity.
- Apical membrane surface density remained unchanged even with high sodium intake.
Conclusions:
- High aldosterone levels and/or Na+ transport during weaning selectively impact the basolateral membrane, driving developmental changes in its surface area.
- The observed morphological changes in superficial colonic enterocytes correlate with functional alterations in Na+ transport, suggesting a structure-function relationship in the immature colon.
Abstract:
The distal colon of suckling (14-day-old) and weanling (27-day-old) rats absorbs Na+ via channel-mediated, electrogenic amiloride-sensitive Na+ transport which disappears after weaning. This transport pathway is induced by aldosterone in superficial cells of colonic epithelium. The purpose of the present study was to correlate the changes in distal colon function with changes in the apical and basolateral cell membrane surface areas of superficial enterocytes. The basolateral but not apical membrane surface density (i.e. surface areas of the basolateral and apical membranes of superficial enterocytes per unit volume of superficial enterocytes) was found to increase between postnatal day 14 and 27 (i.e. during the weaning period). The plasma concentrations of aldosterone were very high during this period and electrogenic amiloride-sensitive Na+ transport and Na, K-ATPase activity were increased significantly. High dietary salt intake during the weaning period prevented the developmental increase of basolateral membrane surface density, inhibited electrogenic amiloride-sensitive Na+ transport and significantly depressed plasma aldosterone levels and Na, K-ATPase activity. Apical cell membrane surface density did not change significantly after a sodium load. Thus, high plasma concentrations of aldosterone and/or high colonic Na+ transport during weaning exert an important and selective effect on the basolateral membrane and are responsible for the developmental changes of this cell membrane surface during weaning. Concomitant changes in the morphology of superficial colonic enterocytes and in colonic Na+ transport suggest that the structure of the immature epithelium is related to its function.