Superior mesenteric artery dilatation alone does not account for glucose-induced hypotension in human sympathetic denervation.
Haemodynamic and hormonal effects of two oral isovolaemic, isoosmotic solutions of 0.5 g/kg and 1.0 g/kg glucose were studied in 10 humans with sympathetic denervation due to primary autonomic failure (AF). Measurements were made supine for 60 min, and also after 5 min 45 head-up tilt, before and 60 min after glucose. There was a similar fall in blood pressure (BP) after each dose, after 0.5 g/kg from 160+/-12 / 87+/-6 to 143+/-13 / 76+/-6 mm Hg, P < 0.05 and after 1.0 g/kg from 160+/-13 / 90+/-6 to 136+/-9 / 76+/-5 mm Hg, P < 0.05. Heart rate, cardiac index and forearm muscle blood flow did not change after either dose. After 0.5 g/kg, superior mesenteric artery blood flow was unchanged but rose significantly after 1.0 g/kg, from 243 (169-395) to 722 (227-982) ml/min, P < 0.05, 15 min after ingestion. BP fell further on tilt 60 min after each dose, but there was no difference between doses. Plasma glucose was higher after 1.0 g/kg but plasma insulin was similar after each dose. Thus, in AF with sympathetic denervation there was no dose-related effect of glucose on supine or postural hypotension. Supine hypotension after glucose was not attributable solely to increased splanchnic blood flow; other factors, including dilatation in other vascular beds may have contributed.
Puvi-Rajasingham
S
S
Division of Neuroscience and Psychological Medicine, Imperial College School of Medicine at St. Mary's, London, UK.
Kimber
J
J
Watson
L P
LP
Mathias
C J
CJ
D000328:Adult; D000368:Aged; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology; D002395:Catecholamines / Q000097:blood; D005947:Glucose / Q000494:pharmacology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007022:Hypotension / Q000139:chemically induced* / Q000503:physiopathology; D007328:Insulin / Q000097:blood; D017538:Mesenteric Artery, Superior / Q000502:physiology*; D008875:Middle Aged; D011187:Posture / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D016037:Single-Blind Method; D013318:Stroke Volume / Q000502:physiology; D016683:Supine Position / Q000502:physiology; D013562:Sympathectomy; D014655:Vascular Resistance / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*
D001786:Blood Glucose; D002395:Catecholamines; D007328:Insulin; D005947:Glucose