Table 2. Pulsatile patterns of progesterone (P4) in the caudal vena cava (CVC) and jugular vein (JV) for cows treated with saline or GnRH during the mid-luteal phase.
| Veins | P4 characteristic | Group | 6 h before treatment | 6 h after treatment |
| CVC | Mean concentration (ng/ml) | Saline (n=3) | 46.6 ± 6.3 | 45.3 ± 2.6 |
| GnRH (n=3) | 48.3 ± 9.7 | 74.8 ± 17.2*† | ||
| Basal concentration (ng/ml) | Saline (n=3) | 34.8 ± 2.7 | 31.3 ± 2.5 | |
| GnRH (n=3) | 29.1 ± 3.2 | 43.6 ± 6.0† | ||
| Pulse frequency (pulses/6 h) | Saline (n=3) | 5.3 ± 0.3 | 3.3 ± 0.3 | |
| GnRH (n=3) | 4.3 ± 0.8 | 4.3 ± 0.3 | ||
| Pulse amplitude (ng/ml) | Saline (n=3) | 31.7 ± 4.5 | 47.3 ± 9.8 | |
| GnRH (n=3) | 51.8 ± 9.4 | 97.7 ± 16.9*† | ||
| JV | Mean concentration (ng/ml) | Saline (n=3) | 5.7 ± 1.2 | 5.4 ± 0.9 |
| GnRH (n=4) | 6.0 ± 1.0 | 7.0 ± 1.3*† | ||
| Basal concentration (ng/ml) | Saline (n=3) | 4.3 ± 0.9 | 4.3 ± 0.5 | |
| GnRH (n=4) | 4.7 ± 0.3 | 5.0 ± 0.4 | ||
| Pulse frequency (pulses/6 h) | Saline (n=3) | 4.7 ± 1.5 | 3.3 ± 0.3 | |
| GnRH (n=4) | 3.5 ± 0.5 | 4.0 ± 0.4 | ||
| Pulse amplitude (ng/ml) | Saline (n=3) | 3.6 ± 0.3 | 3.1 ± 0.3 | |
| GnRH (n=4) | 3.0 ± 0.3 | 3.6 ± 1.2 |
Values are means ± SE. * Different (P<0.05) vs. saline group. † Different (P<0.05) vs. 6 h before treatment.