Abstract
Ten healthy young males were studied with a double-blind, cross-over trial to determine whether or not chlormadinone acetate (CMA), a potent synthetic progesterone, augments hypoxic chemosensitivity.Seven days after CMA administration, inspiratory minute volume (VI) and tidal volume (VT) significantly increased. PaCO2 decreased by 3.0±2.6 (S.D.) Torr (p<0.05) and plasma bicarbonate decreased by 2.9±1.1mM (p<0.01). During CMA administration, the atmospheric hypoxic ventilatory response (HVR), assessed by minute ventilatory (ΔVI/ΔSaO2), and occlusion pressure responses (ΔP.2/ΔSaO2), significantly increased about 1.9 (p<0.05) and 1.6 times (p<0.01) compared to the placebo response, respectively. The calculated normocapnic HVR (ΔVI/ΔSaO2) increased about 2.3 times the placebo run. Hypoxic response evaluated by the withdrawal test, which represents the peripheral chemosensitivity without involving the influence due to secondary hypoxic depression, was about 1.7 times the placebo response (p<0.05). We conclude that CMA augments hypoxic respiratory chemosensitivity.
