Journal of Applied Physiology, Vol 57, Issue 6 1796-1802, Copyright © 1984 by American Physiological Society
Response to hypercapnia and exercise hyperpnea in graded anesthesia
T. Chonan, Y. Kikuchi, W. Hida, C. Shindoh, H. Inoue, H. Sasaki and T. Takishima
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)
