Impaired cardiovagal and vasomotor responses to baroreceptor stimulation in type II diabetes mellitus.
BACKGROUND
In diabetic patients, impairment of the cardiovagal limb of the baroreflex has been well established. However, the role of sympathetic mediated baroreflex vasomotor control of the blood vessels is not well defined. We therefore assessed the vasomotor responses to sinusoidal baroreceptor stimulation in diabetic patients.


METHODS
We studied 14 type II diabetic patients (age; 57 +/- 7 years) and 18 healthy controls (age; 59 +/- 11 years). Oscillatory neck suction was applied at 0.1 Hz to assess the sympathetic modulation of the heart and blood vessels, and at 0.2 Hz to assess the effect of parasympathetic stimulation on the heart. Breathing was paced at 0.25 Hz. Spectral analysis was used to evaluate the oscillatory responses of RR-interval and blood pressure.


RESULTS
The diabetic patients showed a significantly lower RR-interval response (P < 0.05) to the 0.1 Hz neck suction (2.52 +/- 0.50-3.62 +/- 0.54 ln ms2) than the controls (4.23 +/- 0.31-6.74 +/- 0.36 ln ms2). The increase in power of 0.1 Hz systolic blood pressure oscillations during 0.1 Hz suction was also significantly smaller (P < 0.05) in the diabetics (1.17 +/- 0.44-1.69 +/- 0.44 mmHg2) than in the controls (1.60 +/- 0.29 mmHg2-5.87 +/- 1.25 mmHg2). The magnitude of the peak of the 0.2 Hz oscillation in the RR-interval in response to 0.2 Hz neck stimulation was significantly greater (P < 0.05) in the controls (3.42 +/- 0.46 ln ms2) than in the diabetics (1.58 +/- 0.44 ln ms2).


CONCLUSIONS
In addition to cardiovagal dysfunction, baroreflex-mediated sympathetic modulation of the blood vessels is impaired in type II diabetic patients.
Sanya
E O
EO
Autonomic Laboratory, Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054 Erlangen, Germany.
Brown
C M
CM
Dütsch
M
M
Zikeli
U
U
Neundörfer
B
B
Hilz
M J
MJ
D000368:Aged; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology*; D017704:Baroreflex / Q000502:physiology*; D002339:Carotid Arteries / Q000294:innervation; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D020421:Vagus Nerve Diseases / Q000503:physiopathology*