Power spectral analysis of the heart rate variability of goat fetuses during extrauterine incubation.

Our aim is to determine the relationship between heart rate and behavioral states of a fetal goat using power spectral analysis. Electrocardiograms, electrocortical activity, and fetal breathing movements are recorded from 7 goat fetuses during extrauterine incubation. The heart rate power spectrum is classified into very low, low, and high frequency bands, and behavioral states are classified into low-voltage electrocortical activity with fetal breathing movements (LVB), low-voltage electrocortical activity without fetal breathing movements (LVN), and high-voltage electrocortical activity (HVN). There is a significant difference in total power spectral density in the high frequency band between LVN and HVN, and LVN and LVB. The relationship between each fetal behavioral state is assessed by power spectral analysis.

Effect of nutritional restriction in early pregnancy on isolated femoral artery function in mid-gestation fetal sheep.

Unbalanced maternal nutrition affects fetal endocrine and cardiovascular systems, sometimes accompanied by changes in growth, although this is usually in late gestation. We determined the effect of moderate restriction for the first half of gestation of maternal dietary protein, or of total calorific intake on isolated resistance artery function of mid-gestation fetal sheep. Welsh Mountain ewes were nutritionally restricted by 30 % of the recommended nutrient intake (globally restricted) or 30 % of the recommended protein intake (protein-restricted), compared to control ewes fed 100 % of recommended nutrient intake, for ~12 days prior to conception and for the subsequent 70 days of gestation. At mid-gestation, fetal and placental weights were similar in all dietary groups. In isolated femoral arteries, the response curve to noradrenaline was reduced in protein-restricted group fetuses (P < 0.05). Maximal relaxation (P < 0.01) and sensitivity (P < 0.05) to acetylcholine were markedly reduced in protein-restricted group fetuses, and to a smaller extent in globally restricted group fetuses (response curve, P < 0.05). The dilator response (P < 0.05) and sensitivity (P < 0.05) to the alpha2 agonist UK14304 was lower in protein-, but not in globally restricted group fetuses. The response (P < 0.05) and sensitivity (P < 0.05) to the nitric oxide donor sodium nitroprusside were reduced in protein-restricted group fetuses compared to controls. Our data show that dietary imbalance, in particular restricted protein, of the ewe can produce blunting of endothelial-dependent and -independent relaxation in systemic arteries from the mid-gestation fetus. These changes may precede perturbed late-gestation fetal and postnatal cardiovascular control.

Effect of hypoxia on the auditory system of goat fetuses during extrauterine incubation.

AIM: To investigate the effect of hypoxia on the auditory system in fetuses, we attempted to analyze the auditory brainstem response, the middle latency response, and changes of several physiological parameters of goat fetuses during extrauterine incubation. METHODS: We conducted extrauterine incubation of five goat fetuses at around 127days of gestation (term = 148 days). Their physiological parameters, such as fetal heart rate, mean blood pressure, flow rate of carotid artery, as well as the auditory brainstem response and middle latency response, were recorded prior to and during hypoxia, and the two sets of data were compared with each other. RESULTS: In all five cases, the fetal heart rate decreased from 178 +/- 12.2 b.p.m. to 144 +/- 15.2 b.p.m. during hypoxia, while mean blood pressure and flow rate of carotid artery increased from 37.3 +/- 3.7 mmHg to 43.2 +/- 5.1 mmHg, and from 38.5 +/- 5.5mL/min to 47.0 +/- 5.1 mL/min, respectively. The latency of the auditory brainstem response's wave V and of the middle latency response's Pa wave elongated from 5.24 +/- 0.24 ms to 5.69 +/- 0.20 ms, and from 19.2 +/- 1.6 ms to 20.9 +/- 1.4 ms, respectively. CONCLUSIONS: Although fetal compensatory reactions, such as increases in mean blood pressure and flow rate of carotid artery during hypoxia were recognized, elongation of latency, and decrement of amplitude were observed in the auditory brainstem response and middle latency response. These results suggest that hypoxia itself influences the auditory system of the fetus.