Abstract
Abstract Cyclic guanosine 3',5'-monophosphate (cyclic GMP) levels were determined in dog thyroid slices using the protein-binding method. [3H]Guanine incorporation into cyclic GMP was also determined by thin layer chromatography. Basal levels of cyclic GMP in dog thyroid slices were usually 10 to 30 pmoles per g wet tissue. These values were at least 10-fold lower than the cyclic adenosine 3',5'-monophosphate (cyclic AMP) levels. Cyclic GMP levels were significantly increased by acetylcholine (5.5 x 10-7 m to 5.5 x 10-5 m) and NaF (10-2 m) after a 1-min incubation. Increases (5 to 10-fold) were observed after 5- and 20-min incubations with acetylcholine (5.5 x 10-5 m) and after a 20-min incubation with NaF (10-2 m). Neither thyroid-stimulating hormone (100 milliunits per ml) nor prostaglandin E1 (2.8 x 10-5 m) increased cyclic GMP levels during 1-,5-, and 20-min incubations. Acetylcholine and NaF also increased [3H]guanine incorporation into cyclic GMP. The effect of acetylcholine was inhibited by atropine (1.6 x 10-4 m). Acetylcholine and NaF had little or no effect on cyclic AMP levels, while thyroid-stimulating hormone and prostaglandin E1 markedly increased cyclic AMP concentrations. In liver slices of the rat, acetylcholine increased cyclic GMP levels 2-fold, but NaF had no effect. These results indicate that the levels of cyclic GMP and cyclic AMP in dog thyroid slices are regulated by separate hormonal and metabolic mechanisms.
Highlights
Basal levels of cyclic GMP in dog thyroid slices were usually 10 to 30 pmoles per g wet tissue
In liver slices of the rat, acetylcholine increased cyclic GMP levels 2-fold, but NaF had no effect. These results indicate that the levels of cyclic GMP
Addition of 100 pmoles of cyclic AMP contributed 1.5 pmoles to the determination of cyclic GMP. These results are quite consistent with those reported by Murad et al [21]. This contribution of cyclic AMP to the measurement of cyclic GMP may be significant when cyclic GMP is assayed in crude tissue extracts
Summary
Cyclic guanosine 3’,5’-monophosphate (cyclic GMP) levels were determined in dog thyroid slices using the protein-binding method. [aH]Guanine incorporation into cyclic GMP was determined by thin layer chromatography. In liver slices of the rat, acetylcholine increased cyclic GMP levels 2-fold, but NaF had no effect. These results indicate that the levels of cyclic GMP and cyclic AMP in dog thyroid slices are regulated by separate hormonal and metabolic mechanisms. Neither acetylcholine nor NaF increased cyclic AMP concentrations in dog thyroid slices [5], indicating a different mechanism of action. George et al [19] demonstrated that in perfused rat hearts, acetylcholine augmented cyclic GMP levels It seemed of interest, to examine the effects of various substances which stimulate thyroid gland metabolism on cyclic GMP concentrations in this tissue. While these studies were in progress, Kuo et aZ. [20] reported that acetylcholine increased cyclic GMP levels in rat ventricular slices and rabbit cerebellar and cerebral cortex slices
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
