@article{oai:muroran-it.repo.nii.ac.jp:00008305,
 author = {AR, Amos and アー, アーモス and TAZAWA, Hiroshi and 田澤, 皓},
 journal = {室蘭工業大学紀要, Memoirs of the Muroran Institute of Technology},
 month = {Nov},
 note = {application/pdf, Bird embryos may be regarded as developing in their thermo-neutral zone, at rest, and stay in the egg for a fixed period of time until hatching. It is therefore interesting to investigate if they follow the same "rule" set for adult homeotherms, which states that, within a taxonomically or functionally defined category such as mammals or birds, the number of heart beats throughout the life span (sL) is more or less constant. This rule stems from the allometric relationships between heart rate(HR) and body mass (mB) and between sL and mB. As a step towards understanding the general allometric nature of avian embryonic physiology we analyzed the HR values of avian embryos in relation to their incubation span (sI). Data from 30 species were selected from the scientific literature for the analyses. Values obtained from invasive methods which were judged to grossly alter natural incubation conditions, or from undefined or unmatched temperature conditions were not used. These include most values obtained below the first 30% of the incubation. Also, data obtained after internal pipping were discarded since hatching activity influences them. Values for sI and egg mass (mE) as representative of embryonic mass were also collected. Embryonic HR was normalized to 70.1-80% sI. At 20.1-30% sI it was only 85% of the value at 70.1-80% sI and increased to a plateau at about 50.1-60% sI. It was almost constant among species between 50.1- 60% sI and pre-internal pipping(PIP) time and thus, the mean HR value between 50.1-60% sI and 90.1-100% excluding pipped eggs (MHR) was taken as a representative value for each given species. The MHR(bpm) and the corresponding sI (d) values for the 30 species, scaled with mx (g) as follows: MHR=371.1 mE'-0.112' and: sI=12.29 mE'+0.209'. Both powers were significantly different from 0. The product of MHR and sr(MHR ・ sr), representing the total number of heartbeats throughout the incubation, scaled with mE, for the entire data set as follows: MHR sr = 6.565 ・ 10+6 ・ mE+0.096, where the + 0.096 power is significantly different fram 0. Vaiues for MHR ・ sI, from embryos of altricial birds tended to concentrate at the low mE end of the plot while those of the precocial ones tended towards the high end. Separate analyses showed that the mE power for the combined altricial and semi-altricial species (ASA), and the combined precocial and semi precocial species (PSP), of log MHR ・ sr against log mE regressions, were both insignificantly different from 0. Thus, means of MHR ・ sI for ASA and PSP were calculated. The mean ASA value of 7.27 ・ 10+6 heartbeats for MHR ・ sr, was significantly different from the mean PSP value of 10.93 ・ 10+6. The difference of 3.66 ・ 10+6 (33.5%) heart beats can be attributed to either the more advanced stage of the PSP hatchlings at hatch, to the larger mE values of these hatchlings, to the difference on water fractien of the hatchlings or all. The result of a linear regression of MHR ・ sI (in d-1 units) against the rate of sI compietion (the inverse of incubation span, fI; d-1) was: MHR ・ 10-6 = 0.205 + 3.940 ・ fI. Thus, the faster is the average rate of development accomplished per day (shorter incubation) the higher is daily heart rate. Data tended to cluster such that large eggs, mostly of the PSP type with reiatively low MHR, complete 2 to 4% of their incubation per day, whiｌe small, ASA type eggs with relatively high MHR, complete 6 to 8% of their incubation time per day. We conclude that, at this stage of knowledge, the data is insufficient to resolve whether the different modes of hatch stage alone can explain differences in the total number of heartbeats throughout embryonic life among all bird species, or egg mass and water content differences contribute variability. This should be investigated on a larger sample of species in more depth., 特集 : 「動物の心拍リズム」国際シンポジウム発表論文選集},
 pages = {61--71},
 title = {Analysis of Heart Rate in Developing Bird Embryos : Effects of Developmental Mode and Mass},
 volume = {49},
 year = {1999},
 yomi = {タザワ, ヒロシ}
}