Abstract
A radioimmunoassay (RIA) for simultaneous measurement of 4-androstenedione (A), testosterone (T), and 5α-dihydrotestosterone (DHT) in 1 ml of canine plasma was demonstrated. The plasma was extracted by methylenedichloride, then was separated to the proper 3 fractions by Sephadex-LH-20 microcolumn (solvent system: cyclohexane 85/benzene 15/methanol 5). The individual steroid in each fraction was assayed by the RIA. In these assays, an anti-A-3-BSA rabbit serum was used for plasma A, and anti-T-3-BSA serum for both of plasma T and DHT. Each assay for these 3 plasma steroids showed to be satisfactorily sensitive, specific, and accurate. To obtain the basic 3 steroid levels in both of peripheral and spermatic vein plasma, each 8:00 AM sample was collected from 15 male dogs. The plasma steroid levels thus obtained were (ng/ml and SD); in peripheral vein, (A) 0.86±0.75, (T) 1.19±1.05, (DHT) 0.30±0.25, and in spermatic vein, (A) 30.2±18.5, (T) 157±98, (DHT) 17.5±10.7.
Analysing these data, a significant correlation between the two vein plasma levels was suggested. In order to estimate the normal, or common diurnal variations of these plasma steroid levels in male dogs, 5 animals were employed, and each peripheral plasma sample was collected every an hour or two, throughout each 24 hours period. In these data, frequent intermittent peaks of plasma steroids were observed in each dog, and these were thought their own diurnal changes.
It was concluded so, the peripheral plasma levels of A, T and DHT were correlated to those in spermatic vein, and these steroid levels was seemingly reflected by the episodic secretions from the gonad.
