Cerebrovascular reactivity and hypercapnic respiratory drive in diabetic autonomic neuropathy

J Appl Physiol (1985). 2001 Mar;90(3):889-96. doi: 10.1152/jappl.2001.90.3.889.


Because abnormalities in cerebrovascular reactivity (CVR) in subjects with long-term diabetes could partly be ascribed to autonomic neuropathy and related to central chemosensitivity, CVR and the respiratory drive output during progressive hypercapnia were studied in 15 diabetic patients without (DAN-) and 30 with autonomic neuropathy (DAN+), of whom 15 had postural hypotension (PH) (DAN+PH+) and 15 did not (DAN+PH-), and in 15 control (C) subjects. During CO(2) rebreathing, changes in occlusion pressure and minute ventilation were assessed, and seven subjects in each group had simultaneous measurements of the middle cerebral artery mean blood velocity (MCAV) by transcranial Doppler. The respiratory output to CO(2) was greater in DAN+PH+ than in DAN+PH- and DAN- (P < 0.01), whereas a reduced chemosensitivity was found in DAN+PH- (P < 0.05 vs. C). MCAV increased linearly with the end-tidal PCO(2) (PET(CO(2))) in DAN+PH- but less than in C and DAN- (P < 0.01). In contrast, DAN+PH+ showed an exponential increment in MCAV with PET(CO(2)) mainly >55 Torr. Thus CVR was lower in DAN+ than in C at PET(CO(2)) <55 Torr (P < 0.01), whereas it was greater in DAN+PH+ than in DAN+PH- (P < 0.01) and DAN- (P < 0.05) at PET(CO(2)) >55 Torr. CVR and occlusion pressure during hypercapnia were correlated only in DAN+ (r = 0.91, P < 0.001). We conclude that, in diabetic patients with autonomic neuropathy, CVR to CO(2) is reduced or increased according to the severity of dysautonomy and intensity of stimulus and appears to modulate the hypercapnic respiratory drive.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Autonomic Nervous System Diseases / blood
  • Autonomic Nervous System Diseases / physiopathology
  • Blood Flow Velocity
  • Blood Pressure
  • Carbon Dioxide / blood
  • Carbon Dioxide / metabolism*
  • Cerebrovascular Circulation / physiology*
  • Diabetes Mellitus / physiopathology*
  • Diabetic Neuropathies / blood
  • Diabetic Neuropathies / physiopathology*
  • Epinephrine / blood
  • Heart Rate
  • Humans
  • Hypotension, Orthostatic
  • Lung Volume Measurements
  • Male
  • Middle Aged
  • Middle Cerebral Artery / physiology
  • Middle Cerebral Artery / physiopathology*
  • Norepinephrine / blood
  • Partial Pressure
  • Reference Values
  • Respiratory Function Tests
  • Respiratory Mechanics / physiology*


  • Carbon Dioxide
  • Norepinephrine
  • Epinephrine