The perifused Leydig cell: system characterization and rapid gonadotropin-induced desensitization.

To determine the kinetic characteristics of gonadotropin-induced steroidogenesis and secretion, acute preparations of collagenase-dispersed 55- to 60-day-old rat Leydig cells were suspended in a 2-ml column of Bio-Gel P2 and perifused at a constant rate of 0.5 ml/min with medium 199-0.1% bovine serum albumin at 35 C. Suspended Leydig cells (3-10 × 106) had a limited functional timespan when assessed on the basis of gonadotropin-stimulated testosterone (T) output. Cells were resistant to gonadotropin during both the initial 40 min and after 240 min of perifusion. The basal T output started high, became steady between 40–180 min, and thereafter declined to undetectable levels. Ninety percent of the cells remained trypan blue negative after 240 min of column suspension. During the functional period, rapid and large increases in T release could be induced by a variety of gonadotropins with interstitial cell-stimulating activity in addition to 8-bromo-cAMP. The time delay between gonadotropin contact with the ...