Biomedical subjects
Publications and source records attributed to T Chonan.
We studied the effect of exercise on bronchial responsiveness to methacholine in 10 asthmatics. Bronchial responsiveness to methacholine was compared before and 20 minutes after exercise. Although five out of 10 asthmatics showed exercise-induced bronchoconstriction (EIB), nine out of 10 asthmatics became more hypersensitive after exercise, irrespective of EIB.
We examined the relationship between response to hypercapnia and ventilatory response to exercise under graded anesthesia in eight dogs. The response to hypercapnia was measured by the CO2 rebreathing method under three grades of chloralose-urethan anesthesia. The degrees of response to hypercapnia (delta VE/delta PETCO2, 1 X min-1 X Torr-1) in light (L), moderate (M), and deep (D) anesthesia were 0.40 +/- 0.05 (mean +/- SE), 0.24 +/- 0.03, and 0.10 +/- 0.02, respectively, and were significantly different from each other. Under each grade of anesthesia, exercise was performed by electrically stimulating the bilateral femoral and sciatic nerves for 4 min. The time to reach 63% of full response of the increase in ventilation (tauVE) after beginning of exercise was 28.3 +/- 1.5, 38.1 +/- 5.2, and 56.0 +/- 6.1 s in L, M, and D, respectively. During steady-state exercise, minute ventilation (VE) in L, M, and D significantly increased to 6.17 +/- 0.39, 5.14 +/- 0.30, and 3.41 +/- 0.16 1 X min-1, from resting values of 3.93 +/- 0.34, 2.97 +/- 0.17, and 1.69 +/- 0.14 1 X min-1, respectively, while end-tidal CO2 tension (PETCO2) in L decreased significantly to 34.8 +/- 0.9 from 35.7 +/- 0.9, did not change in M (38.9 +/- 1.1 from 38.9 +/- 0.8), and increased significantly in D to 47.3 +/- 1.9 from 45.1 +/- 1.7 Torr.(ABSTRACT TRUNCATED AT 250 WORDS)
To study the time-course of exercise-induced bronchoconstriction (EIB) in asthmatics, we have developed a method for continuous measurement of respiratory resistance using the forced oscillation technique during tidal breathing throughout the exercise challenge. Twenty-three out of 38 asthmatics were exercise responders and five of these responders showed an increase in resistance during exercise. The present technique may be clinically applicable in examination of different types of EIB and as a screening test.
Bronchial responses to inhaled histamine significantly increased on the 2nd day and the 7th day after influenza virus vaccination in monkeys. Bronchial responses to inhaled methacholine also significantly increased on the 14th day and the 21st day after the vaccination.
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We studied the effects of local high frequency mechanical vibration on ventilatory (VE) and occlusion pressure (P0.1) responses to CO2 rebreathing in twelve normal subjects. Three kinds of vibration procedures were employed: a) sustained vibration over the tendon of the quadriceps femoris near the knee, b) sustained vibration of the right 2nd or 3rd parasternal intercostal spaces and c) 'in-phase' chest wall vibration applied during inspiration on the right 2nd or 3rd parasternal intercostal spaces and during expiration on the right 9th or 10th intercostal spaces anterior to the midaxillary line. The slopes of VE response to hypercapnia (delta VE/delta PETCO2) were 2.05 +/- 0.26 (mean +/- SE), 2.48 +/- 0.24, 2.82 +/- 0.32 and 3.35 +/- 0.38 l.min-1/mmHg in the control state, during tendon vibration of quadriceps femoris, sustained chest wall vibration and 'in-phase' chest wall vibration, respectively. This sequential increase in slopes was significant compared to the control values. The effect of vibration on the P0.1 response to hypercapnia was similar to that of VE. We conclude that local mechanical vibration facilitates responsiveness to hypercapnia.