Twenty-four hours prior to each experiment, the subjects were instructed to avoid strenuous exercise and to maintain their ordinary diet but to avoid food with a high salt content. Subjects arrived at the laboratory at least two hours after a light meal. Before starting the experiment, the subjects rested in a comfortable chair in the sitting position. A catheter (0.47 mm ID, 24 gage) was placed in the brachial artery of the nondominant arm for arterial blood sampling, and for arterial blood pressure measurement by connecting to a pressure transducer (DX-200, Nihon Kohden) positioned at the level of the right atrium in the midaxillary line, fastened to the subject, and connected to a pressure monitoring system (RM-6000, Nihon Kohden). The experiment started 20–30 minutes after the catheter was placed.
In order to characterize both the controller and plant properties, the participants sequentially underwent two experimental procedures in the sitting position: a resting hypercapnia test and a hyper/hypoventilation test, on the same day.
In order to characterize both the controller and plant properties, the participants sequentially underwent two experimental procedures in the sitting position: a resting hypercapnia test and a hyper/hypoventilation test, on the same day.