Analysis of alveolar PCO2 control during the menstrual cycle

Autor: Takano, Nariko, Sakai, Akemi, Iida, Yasuko
Zdroj: Pflügers Archiv European Journal of Physiology; April 1981, Vol. 390 Issue: 1 p56-62, 7p
Abstrakt: We attempted to analyze how $$P{\text{A}}_{{\text{CO}}_{\text{2}} } $$ is regulated during progesterone-induced hyperventilation in the luteal phase. A model for the CO2 control loop was constructed, in which the function of the CO2 exchange system was described as $$P_{A_{CO_2 } } = 0.863 \times \dot V_{CO_2 } /\dot V_A {\text{ }}(gain{\text{ }}H = dP_{A_{CO_2 } } /d\dot V_A )$$ and that of the CO2 sensing system as $$\dot V_A {\text{ = }}S{\text{(}}P_{{\text{A}}_{{\text{CO}}_{\text{2}} } } - B{\text{)}}$$ . Using this model, we estimated (1) the primary increase in $$\dot V_A (\Delta \dot V_A (op))$$ produced by progesterone stimulation and (2) the effectiveness (E) of the loop to regulatePACO2, defined as ΔPACO2 (op)/ΔPACO2 (cl) in which op signifies open-loop and cl, closed-loop. These respiratory variables were investigated throughout the menstrual cycle in 8 healthy women. During the luteal phase, on average, $$\dot V_A $$ increased by 9.4% andPACO2,B andH decreased by 0.33 kPa (2.5 mm Hg), 0.47 kPa (3.5 mm Hg) and 13.6%, respectively, whileS and $$\dot V_{CO_2 } $$ did not change significantly. δ $$\Delta \dot V_A (op)$$ (op) increased progressively on successive days of the luteal phase whileE remained unchanged at a value of 7.9, thus there was a progressive decrease inPACO2. The decrease inH was considered to lessen ΔPACO2 (op) and so reduce the final deviation ofPACO2 (ΔPACO2 (cl)) during the luteal phase. The decrease inB was found to be dependent on δ $$\Delta \dot V_A (op)$$ (op).
Databáze: Supplemental Index
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