The effect of gradient osmotic pressure on the proliferation of inner medullary collecting duct cell in rats

Abstract

Objective To investigate the change of the proliferation of inner medullary collecting duct (IMCD) cell under the sodium chloride gradient osmotic pressure circumstance.Methods Collagenase digostion and hypotonic dissolve were used to isolate and culture primary IMCD cell of Sprague-Dawley rat.Cells were divided into hypotonic medium(200 mosmol/kg),isotonic medium(300 mosmol/kg) and hpertonic medium(600 mosmol/kg) groups,after 90% confluence in the normal culture medium.The cellular cytotoxicity was analyzed by MTT assay(methyl thiazolyl tetrazolium) and flow cytometer was used to detect cell cycle and apoptosis ratio.Results IMCD cells were resistant to osmotic pressure change.Cell apoptosis ratio under hypertonic circumstance was significantly higher than hypotonic and isotonic groups after 12 hours treatment(1.1%±0.10% vs 0.565% ±0.096%,0.104%±0.08%,P＜0.05).Cell apoptosis ratio in hypertonic circumstance was slightly lower than hypotonic group (P＞0.05) but higher than isotonic group(P＞0.05) after 24 hours treatment.Conclusion The proliferation of IMCD cell was inhibited under hypertonic circumstance,especially after 12 hours treatment,and the inhibitory effect of hypotonic circumstance increased after 24 hours treatment. Key words: Inner medullary collecting duct cell; Osmotic pressure; Cell cycle; Apoptosis