Decreased cyclic GMP levels in rat cecum mucosa during adaptive stimulation of Na−K-ATPase

Summary In rat cecal mucosa, Na–K-ATPase specific activity and sodium and fluid absorption were increased by giving polyethylene glycol administration with the drinking water. Whereas cyclic AMP levels were unchanged, cyclic GMP was reduced by about 50%. This finding suggests a regulatory role of cyclic GMP in intestinal sodium and fluid absorption.Acknowledgments. We thank Miss U. Kautz for engaged technical assistance, Dr G. Schultz, Pharmakologisches Institut der Universität Heidelberg, for valuable discussions and suggestions, and Dr. K.D. Schultz, Heidelberg, for generous supply of the cGMP antibody and 125-iodinated succinyl tyrosyl methyl ester of cGMP.Supported by the Deutsche Forschungsgemeinschaft, grant Lo 114/7.