著者

升田 吉雄 吉田 明夫 林 文明 佐々木 健 本田 良行

出版者

THE PHYSIOLOGICAL SOCIETY OF JAPAN

雑誌

The Japanese Journal of Physiology (ISSN:0021521X)

巻号頁・発行日

vol.32, no.3, pp.327-336, 1982 (Released:2011-06-07)

参考文献数

25

被引用文献数

14 19

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The steady-state ventilatory responses to hypercapnia and hypoxia in 7 assisted breath-hold divers (Funado) were compared with those in 7 normal sedentary controls.Ventilatory response to hypercapnia was measured from the slope of the hyperoxic VN-PETCO2 line, where VN was normalized minute ventilation using the allometric coefficient and PETCO2 end-tidal PCO2. The slope of this line in the Funado (1.48±0.54 liters·min-1·Torr-1) was significantly less than in the control (2.70±1.08 liters·min-1·Torr-1)(p<0.025). On the other hand, hypoxic sensitivity estimated by hyperbolic and exponential mathematical equations was not found to be significantly different between the two groups, although estimated increments in ventilation using the hyperbolic equation exhibited significantly lower response in the Funado than in the control only when PETO2 decreased lower than 50 Torr (p<0.05).These findings in the Funado were different from our previous observations obtained in unassisted breath-hold divers (Kachido), in whom no obvious attenuations in CO2sensitivity were seen. This difference was assumed to be derived from more hypercapnic and hypoxic conditions produced in the Funado than in the Kachido during diving activities.

著者

升田 吉雄 吉田 明夫 林 文明 佐々木 健 本田 良行

出版者

THE PHYSIOLOGICAL SOCIETY OF JAPAN

雑誌

The Japanese Journal of Physiology (ISSN:0021521X)

巻号頁・発行日

vol.31, no.2, pp.187-197, 1981 (Released:2011-06-07)

参考文献数

21

被引用文献数

22 26

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The ventilatory responses to hypoxia and hypercapnia of 5 Amas (Kachido) were compared with those of 5 controls of similar ages, physical characteristics and lung volumes. The responses to hypoxia and hypercapnia were analyzed by the equations originally proposed [a] by Lloyd et al. and [b] by Kronenberg et al. as follows:[a] VN=(PCO2-B')·D·(1+A/PO2-C) +VB'.[b] VN=(PCO2-B')·D·(1+R0·exp (-k·PO2)) +VB'.The CO2-response slope in hyperoxia, D, of the Ama (1.820±0.441 liters·min-1·Torr-1) was slightly higher than that of the control (1.148±0.586 liters·min-1·Torr-1), but the difference was not significant. However, the slope of CO2-response in hypoxia at PETO2=44 Torr, S44, was almost the same in the two groups (Ama, 1.822±0.689 liters·min-1·Torr-1; control, 1.742±0.902 liters·min-1·Torr-1). The ratio of S44 to D was significantly lower (p<0.05) in the Ama (1.039±0.377) than in the control (1.529±0.249). Comparing the hypoxic response in terms of the ventilation ratio (VR), the elevation of ventilation with augmentation of hypoxia in the Ama was exceeded by that in the control.Thus, it was suggested that the difference in the ventilatory response to hypoxia between the Ama (Kachido) and the control may have been derived from the respiratory adaptation of the Ama (Kachido) acquired by their daily diving activities.

著者

本田 良行 林 文明 吉田 明夫 升田 吉雄 佐々木 健

出版者

THE PHYSIOLOGICAL SOCIETY OF JAPAN

雑誌

The Japanese Journal of Physiology (ISSN:0021521X)

巻号頁・発行日

vol.31, no.2, pp.181-186, 1981 (Released:2011-06-07)

参考文献数

15

被引用文献数

3 5

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Relative contributions of chemical and non-chemical respiratory stimulations to breath-holding time (BHT) were examined in assisted (Funado) and unassisted (Kachido) breath-hold divers (Ama). In the Funado the magnitude of the chemical contribution was reduced, though statistically not significant. On the other hand, in the Kachido no difference in chemical contribution was seen from the control. This was considered to be due to the fact that ventilatory response to CO2 was reduced in the Funado, but not in the Kachido. Despite the decreased contribution of CO2 drive to BHT, absolute BHT in the Funado was not prolonged. This may be related to sensitization of the respiratory centers to non-chemical stimulation. Such adaptation would be effective for preventing the danger of losing consciousness in the Funado who face extreme hypoxia on returning to the surface from a dive.