Triiodothyronine induces an increase in cyclic GMP in bullfrog tadpole tissues.
Cyclic GMP (cGMP) and cyclic AMP (cAMP) were determined in bullfrog tadpole liver and tail fin using 125I-RIA. cGMP increased approx. 100% 1-6 h after the injection of T3 (3 X 10(-10) mol/g body wt.). Reducing the dose of T3 to 1, 3, and 10 X 10(-11) mol/g body wt. provided increases in cGMP of 50-100% above the control value after 2 h. In contrast, only small increases (less than 20%) in cAMP were observed 2-24 h after T3 injection. We conclude that T3 produces a rapid and significant increase in cGMP in the liver and tail fins of premetamorphic tadpoles. These results suggest that thyroid hormones in amphibia may not be an exclusively nucleus-mediated hormone.
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D007814:Larva / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D009928:Organ Specificity; D011892:Rana catesbeiana; D013623:Tail; D014284:Triiodothyronine / Q000494:pharmacology*
D014284:Triiodothyronine; D000242:Cyclic AMP