Effects of Some Hormonal and Other Factors on the Excretion of Guanosine 3',5'-Monophosphate and Adenosine 3',5'-Monophosphate in Rat Urine

Abstract The urinary excretion of cyclic adenosine 3',5'-monophosphate and cyclic guanosine 3',5'-monophosphate has been studied in rats in various hormonal states. Hypophysectomy lowered the excretion of cyclic GMP to less than half of normal while reducing only slightly the excretion of cyclic AMP. The effect of the operation on cyclic GMP excretion was not associated with a decrease in the nucleotide content of the whole animal. The effect of hypophysectomy on cyclic AMP excretion was completely reversed by hydrocortisone while cyclic GMP excretion was unaffected by the hormone. A large dose of thyroxine in combination with hydrocortisone completely reversed the effect of hypophysectomy on cyclic GMP, but a more nearly physiological dose of thyroxine with hydrocortisone was only partially effective. A mixture of six purified anterior pituitary hormones completely reversed the effect of hypophysectomy on cyclic GMP excretion. Cyclic GMP excretion was lowered by adrenalectomy and restored to normal by hydrocortisone. Thyroparathyroidectomy also decreased the excretion of cyclic GMP, and this was reversed by maintenance doses of thyroxine. Cyclic AMP excretion was not demonstrably affected by adrenalectomy but was lowered by thyroparathyroidectomy and restored to near normal by thyroxine. The injection of glucagon produced a marked increase in cyclic AMP excretion while having no effect on cyclic GMP excretion. Excretion of both nucleotides relative to body weight was lower in old than young animals and appeared to be independent of the urine volume. When urine was collected for 2 consecutive days, nucleotide excretion was consistently lower during the 2nd day. Relative to the levels of the two nucleotides contained in the whole normal animal, proportionately more cyclic GMP than cyclic AMP was excreted, and the amounts of both nucleotides excreted in a day exceeded the total body content as measured at one point in time.