TRH-degrading enzyme activity in peripheral and pituitary-portal plasma of the rat.
The enzymatic degradation of TRH was measured in peripheral and pituitary-portal plasma. Enzyme activity in peripheral plasma was 3.20 pg/min/mug plasma protein; in pituitary-portal plasma the rate of degradation was only 0.83 pg/min/mug protein. After dialysis, which removed virtually all endogenous TRH and LHRH, enzyme activity in peripheral and portal plasma was 2.24 and 0.60 pg/min/mug respectively. These data suggest that portal plasma contains large concentrations of unidentified substances which are competitive inhibitors or substrates for the enzyme or that portal plasma contains less TRH-degrading enzyme.
D000818:Animals; D001798:Blood Proteins; D004798:Enzymes / Q000097:blood*; D008297:Male; D010902:Pituitary Gland / Q000201:enzymology*; D051381:Rats; D013973:Thyrotropin-Releasing Hormone / Q000097:blood*
D001798:Blood Proteins; D004798:Enzymes; D013973:Thyrotropin-Releasing Hormone