Measurement of the rate of secretion, peripheral metabolism and interconversion of cortisol and cortisone in adult conscious male guinea-pigs.

Metabolism of the cortisol (F) and the cortisone (E) was studied by continuous infusion of [14C]-F and [3H]-E in adult conscious male guinea-pigs. Parameters, calculated from the specific activities of F and E, are expressed in mumoles/24 h : production rate of F (PRF) = 8 +/- 1 and E (PRE) = 4.9 +/- 0.7 ; secretion rate of F (QF) = 7.1 +/- 0.9 and E (QE) = 0.9 +/- 0.4 ; rate of irreversible metabolism of F (rF) = 6.2 +/- 0.9 and E (rE) = 1.8 +/- 0.3 ; percentage of transfer of F into E = 59 +/- 4% and E into F = 80 +/- 3%. These results demonstrate that adrenal gland in the adult male guinea-pig secretes essentially cortisol and little or no cortisone. Practically all the pool of E is derived from transformation of F into E ; the major part of E production is reconverted into F.