Effect of Chronic Hypokalemia on Expression of Colonic H/K-ATPase a Subunit mRNA in Rat Uterus / 대한해부학회지

Potassium (K+) balance is achieved by the control of urinary K+ excretion and by the control of K+ absorption from the digestive tract. While it is well established that colonic H/K-ATPase a subunit mRNA is expressed in the kidney, distal colon, and uterus, little is known about the cellular localization and expression levels of this gene in chronic hypokalemia. Accordingly, Northern analysis and in situ hybridization (ISH) were carried out to analyze the expression of mRNA encoding the colonic H/K-ATPase a subunit in normal and potassium-restricted (2 weeks) rats. Northern analysis demonstrated that colonic H/K-ATPase a subunit mRNA was abundantly expressed in normal and potassium-restricted rat uterus. Abundance of colonic H/K-ATPase a subunit mRNA in potassium-restricted rat uterus was increased but, not statistically significant compared to that of controls. By ISH, mRNA for colonic H/K-ATPase a subunit was detected in the endometrial epithelial cells and the uterine glands. Both groups exhibited comparable cellular patterns of labeling, but signal intensity of potassium- restricted rats was higher than normal rats. The endometrial epithelial cells exhibited a mixture of hybridization signal intensity. Most cells had intense hybridization signal for colonic H/K-ATPase a subunit mRNA, some cells had moderate, and a few cells had weak. In summary, colonic H/K-ATPase a subunit mRNA is expressed in the endometrial epithelial cells and the uterine glands. These results suggest that two (or more) H/K-ATPase a subunit isoforms are present in rat uterus and this gene contributes to potassium reclamation during chronic hypokalemia to regulate the pH and/or electrolyte concentration of uterine fluid.

Effects of Chronic Hypokalemia on Rat Distal Colon / 대한해부학회지

Recent molecular and physiological studies suggested that at least two distinct H/K-ATPase activities are present in the mammalian colon. Potassium (K+) balance is achieved by the control of urinary K+ excretion and by the control of K+ absorption from the digestive tract. The colon also participates substantively in the regulation of systemic K+ homeostasis. Northern analysis and in situ hybridization (ISH) for analyzing the expression of mRNA encoding the colonic H/K-ATPase a subunit and EM study for morphologic adaptations were carried out in normal and potassium-deprived (2 weeks) rats. Northern analysis demonstrated that colonic H/K-ATPase a subunit mRNA is abundantly expressed in normal rat distal colon. Abundance of colonic H/K-ATPase a subunit mRNA in potassium-deprived rat distal colon was not significantly increased compared to controls. By ISH, mRNA for colonic H/K-ATPase a subunit was detected in the surface epithelial cells, Goblet cells, and upper third of the intestinal gland. Both groups exhibited comparable cellular patterns of labeling and signal intensity. The surface epithelial cells exhibited a mixture of hybridization signal intensity. Most cells had intense hybridization signal for colonic H/K-ATPase a subunit mRNA and some cells had moderate, and a few cells had weak. Occasionally, strong hybridization signal was detected in the lower portion of the intestinal gland. EM study demonstrated that two types of surface columnar epithelial cells were present in normal distal colon and included type 1 cells with more abundant vesicles in supranuclear cytoplasm and type 2 cells with moderate amount of vesicles. In potassium-deprived distal colon, type 2 cells were only present in surface columnar epithelial cells. Others were not significant differences between two groups. These results suggest that two (or more) H/K-ATPase a subunit isoforms are present in rat distal colon, and colonic H/K-ATPase asubunit gene does not significantly contribute to potassium conservation during chronic hypokalemia in spite of abundant expression of this gene.