Endogenous opioid system during inspiratory loading in patients with type I diabetes.
To investigate the activity of the endogenous opioid system in patients with insulin-dependent diabetes mellitus during ventilatory stress situations, we measured plasma beta-endorphin levels in six male and five female diabetic patients breathing against fatiguing inspiratory resistive loads. The patients had to generate with each inspiration an esophageal pressure (Pes) 80% of maximum until they were exhausted and could no longer develop target Pes. The loaded breathing run was repeated three times with a 1-min interval between each run. Duty cycle, tidal volume, and breathing frequency were constant in all tasks. For each run plasma beta-endorphin levels were measured, inspiratory effort sensation assessed using a modified Borg scale, and inspiratory muscle endurance evaluated by the length of time the task could be maintained (Tlim). A group of 11 sex-, age-, height-, and weight-matched healthy individuals served as control subjects. Tlim was significantly lower in the diabetic patients. Evaluating respiratory effort during the three test runs in control subjects at a time corresponding to the break point of loaded breathing in patients showed significantly lower Borg ratings in the control group than in the patient group. Baseline plasma beta-endorphin was significantly lower in the diabetic patients (10.6 +/- 2.1 versus 27.0 +/- 4.2 pg/ml, p < 0.01). Additionally, whereas resistive loaded breathing caused a further increase in plasma beta-endorphin concentration in the control group (p < 0.005), absolutely no increase was found in the diabetic patients. We conclude that the endogenous opioid system in insulin-dependent diabetic patients does not respond to stress caused by breathing against fatiguing inspiratory resistive loads.
Wanke
T
T
Pulmonary Department, Lainz Hospital, Vienna, Austria.
Lahrmann
H
H
Auinger
M
M
Merkle
M
M
Formanek
D
D
Ogris
E
E
Irsigler
K
K
Zwick
H
H
D000328:Adult; D000403:Airway Resistance; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000503:physiopathology; D004947:Esophagus / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D010807:Physical Endurance; D011312:Pressure; D012119:Respiration / Q000502:physiology*; D015656:Respiratory Mechanics; D012132:Respiratory Muscles / Q000503:physiopathology; D001615:beta-Endorphin / Q000097:blood*
D001615:beta-Endorphin