Increase of cyclic GMP induced in murine thymocytes by thymosin fraction 5.
Using a radioimmunoassay (RIA) for the determination of adenosine 3'5' cyclic monophosphate (cAMP) and an acetylation-RIA procedure to measure guanosine 3'5' cyclic monophosphate (cGMP), we observed that cGMP levels, but not cAMP levels, were significantly elevated in murine thymocytes which had been incubated with preparations containing the thymic hormone, thymosin. Stimulation of intracellular cGMP levels was seen as early as 1 minute after incubation with thymosin fraction 5 and was maximal at approximately 10 minutes. Dose response studies indicated an optimum stimulation of cGMP with a thymosin concentration of 100 microg/ml. A control spleen fraction prepared by an identical procedure as fraction 5 did not affect the levels of either cyclic nucleotide.
Naylor
P H
PH
Division of Biochemistry, The University of Texas Medical Branch, Galveston, Texas 77550, USA.
Sheppard
H
H
Thurman
G B
GB
Goldstein
A L
AL
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D051379:Mice; D011863:Radioimmunoassay; D013947:Thymosin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D013950:Thymus Gland / Q000187:drug effects* / Q000378:metabolism*; D013997:Time Factors
C033782:thymosin fraction 5; D013947:Thymosin; D000242:Cyclic AMP; D006152:Cyclic GMP