| Popis: |
Using [ 3 H]tryptophan as a precursor, the rate of production and release of cardioacceleratory hormone-I and -II by isolated corpora cardiaca of Periplaneta americana was quantified in vitro . Striking differences in the rate of radiolabelled tryptophan incorporation into these peptides occurred depending on the carbohydrate composition of the incubation media. With medium containing only sucrose, a low rate of hormone accumulation was found. This rate increased more than five-fold when 50 mM trehalose was included in the medium. The effect of trehalose was rather specific and could not be mimicked by 5 mM glucose, although extremely high levels of glucose did stimulate some glands. The enhanced rate of cardioacceleratory hormone-I and -II accumulation appears to be due to an increased rate of peptide synthesis rather than a lowered rate of release. |
