Metabolic clearance rate, production rate, and source of progesterone in donkeys with fetuses of different genotypes.

摘要: \s=venus\ donkey) conceptuses are appreciably higher than in donkeys carrying normal donkey conceptuses, or mares horse (Allen, 1975). In contrast, PMSG concentrations low mule (\s=mars\donkey \m=x\\s=venus\horse) compared with (Bielanski, Ewy & Pigoniowa, 1956; Clegg, Cole, Howard Pigon, 1962; Allen, 1969), although progestagen unaffected Peripheral plasma as high 800 ng/ml have been recorded hinny Concentrations of this magnitude occur only rarely species so far investigated during gestation. guinea-pigs and other hystricomorph rodents, such progesterone associated a marked decrease metabolic clearance rate the production protein affinity for (Heap Ulingworth, 1974). pregnant women they may arise from substantial increase rates due to increased placental secretion. The following experiments were carried out determine whether either these mechanisms is influenced by fetal genotype equids. rate(MCR)and rate(PR) measured 3 conceptus, 4 conceptus 1 mare conceptus. methods used infusion [7a-3H]progesterone, analysis blood samples, calculation MCR PR its conversion metabolites (Cbb) described Bedford, Harrison Heap(l 972). Validation analytical techniques tracer kinetic studies showed no metabolism pCi [7a-3H]progesterone (10 ml) when incubated at 37°Cfor3 h. [3H]Progesterone jugular venous taken continuous labelled into opposite vein reached steady state h after start infusion. mean coefficient variation least samples steady-state conditions was 12-3% experiments). concentration endo¬ genous arterial similar simultaneously under anaesthesia, implying that head extraction negligible. Plasma determined radioimmunoassay (Heap, Gwyn, Laing Walters, 1973 ; method A). antiserum studies, BF 465 No. 6 (kindly supplied Dr . J. A. Furr), raised goat immunized against conjugated bovine serum albumin through 11-position. main cross-reactants tested (100%), lla-hydroxypregn-4-ene-3,20-dione (117-0%), 5a-pregnane-3,20dione (35-3%), lls-hydroxypregn-4-ene-3,20-dione (350%). Progesterone major study, values presented referred concentrations. also one experiment fetus on Day 64 pregnancy (ovulation = 0) competitive binding (Allen Rossdale,