成長するニワトリ雛における心拍リズム(「動物の心拍リズム」国際シンポジウム発表論文選集)

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Chick instantaneous heart rate(IHR) was determined by electrocardiogram measured noninvasively from day of hatch to day 6. In experiment I, IHR was measured for 1-h periods twice a day, in daytime and at night, to investigate heart rate fluctuations (variability and irregularities). Chick IHR was substantially arrhythmic and spontaneous tachycardia of 100-150bpm dominated HR fluctuations. We categorized the fluctuations into three types; 1) type I as a widespread baseline HR (20 to 50bpm) due to respiratory arrhythmia, with a mean oscillatory frequency of 0.74Hz (range 0.4-1.2Hz); 2) type II as low frequency oscillations in HR baseline, at a mean of 0.07Hz (range 0.04-0.10Hz), of uncertain origin; and 3) type III as non-cyclic irregularities, dominated by frequent transient tachycardia. In experiment II, we determined the diurnal rhythms of chick IHR over 24-h periods and under conditions of a natural photoperiod, thermoneutrality and with feed available throughout the first week after hatching. Chick IHR was very variable in the daytime (250-500bpm), due in part to feeding and activity, and decreased to a diurnal low (200-350bpm) at night, when mean HR was stable. HR fluctuations persisted throughout the diurnal cycle.
室蘭工業大学の論文
1999-11-30