[Effects of autonomic blockades, beta-adrenergic agent and cholinergic agent on the FHR variability of "Shiba goats"].

The effects of atropine, propranolol, isoproterenol and acetylcholine on the fetal heart rate variability were studied using chronically prepared fetal goats. When atropine, propranolol and atropine-propranolol were injected the STVs decreased by 45.2%, 43.2% and 57.3%, respectively; LTVs also decreased by 72.3%, 52.2% and 73.3%, respectively. STVs and LTVs increased by 39.5% and 34.5% with the injection of isoproterenol, and decreased by 27.6% and 22.7% with acetylcholine. These results suggest that FHR variability represents a change in the heart rate due to reciprocal innervation of adrenergic and cholinergic systems; moreover, the activity of the heart itself exerts some influence on variability. It is also suggested that LTV more strongly reflects autonomic nervous tone whereas STV more strongly reflects heart activity.