AJP - Regulatory, Integrative and Comparative Physiology, Vol 258, Issue 6 1411-R1416, Copyright © 1990 by American Physiological Society
Influence of acid-base status on plasma catecholamines during exercise in normal humans
S. R. Goldsmith, C. Iber, C. D. McArthur and S. F. Davies
Department of Medicine, Hennepin County Medical Center, Minneapolis, Minnesota 55455.
The influence of acid-base status on plasma catecholamines during exercise
was investigated in six healthy volunteers. Incremental exercise to 175 W
was performed on a bicycle ergometer under four conditions: 1) control, 2)
during forced hyperventilation (HV), 3) after pretreatment with
acetazolamide (AZE), and 4) while breathing 4% CO2. Resting plasma
norepinephrine (PNE) and epinephrine (PE) were not different among the four
protocols despite higher resting pH during HV and lower resting pH after
AZE [control, 7.4 +/- 0.02; HV, 7.48 +/- 0.03 (P less than 0.005); AZE,
7.36 +/- 0.01 (P less than 0.005) (P values indicate significant
differences from the control protocol)]. Resting pH was not different from
control during the 4% CO2 study (7.4 +/- 0.01). At the 175-W exercise load,
there were significant differences in both pH and PNE. During the control
test, pH was 7.38 +/- 0.02, PNE was 951 +/- 164 pg/ml, and PE was 264 +/-
132 pg/ml. During HV, pH was 7.46 +/- 0.5 (P less than 0.001), PNE was 976
+/- 67 pg/ml, and PE was 210 +/- 27 pg/ml. After AZE, pH was 7.31 +/- 0.2
(P less than 0.001), PNE was 1,866 +/- 561 pg/ml (P less than 0.005), and
PE was 382 +/- 264 pg/ml. While subjects breathed 4% CO2, pH was 7.29 +/-
0.02 (P less than 0.001), PNE was 1.842 +/- 617 pg/ml (P less than 0.01),
and PE was 467 +/- 275 pg/ml.(ABSTRACT TRUNCATED AT 250 WORDS)
