title: Changes in forearm blood flow at elevated ambient temperature and their role in the apparent impairment of glucose tolerance.
abstract: 1. Antecubital venous plasma glucose and insulin concentrations after ingestion of 75 g of glucose were higher in six normal subjects when studied at an ambient temperature of 33 degrees C at an ambient temperature of 23 degrees C; the mean area under the glucose-time curve increased from 833 at 23 degrees C to 990 mmol min-1 at 33 degrees C, that for insulin from 5300 to 7900 m-units min 1-1. 2. Core temperature was elevated by 0.5 degree C at 33 degrees C ambient, although there was no marked stress response as judged by plasma levels of catecholamines, cortisol and growth hormone; at 2 h after glucose ingestion, mean noradrenaline levels were lower at 33 degrees C than at 23 degrees C (1.1 at 33 degrees C vs 1.8 nmol/l at 23 degrees C), adrenaline slightly higher (0.18 at 33 degrees C vs 0.09 nmol/l at 23 degrees C), cortisol and growth hormone unchanged. 3. Forearm blood flow was markedly elevated at 33 degrees C ambient (mean total flow 9.1 at 33 degrees C vs 1.8 ml min-1 100 ml-1 at 23 degrees C), as were antecubital venous partial pressure of oxygen (mean 10.1 at 33 degrees C vs 5.6 kPa at 23 degrees C) and oxygen saturation (mean 92% at 33 degrees C vs 70% at 23 degrees C). There was a positive correlation between oxygen saturation and area under the glucose tolerance curve. 4. In separate experiments, arterialized glucose concentrations were measured after glucose ingestion at 23 degrees C ambient.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Sheik Rashid Diabetes Unit, Radcliffe Infirmary, Oxford, U.K.
authors.forename: K N
authors.initials: KN
authors.lastname: Frayn
authors.forename: P L
authors.initials: PL
authors.lastname: Whyte
authors.forename: H A
authors.initials: HA
authors.lastname: Benson
authors.forename: D J
authors.initials: DJ
authors.lastname: Earl
authors.forename: H A
authors.initials: HA
authors.lastname: Smith
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002245:Carbon Dioxide / Q000097:blood; D004361:Drug Tolerance; D005260:Female; D005542:Forearm / Q000098:blood supply*; D005947:Glucose / Q000493:pharmacokinetics*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D012039:Regional Blood Flow; D013696:Temperature
chemical_list: D001786:Blood Glucose; D007328:Insulin; D002245:Carbon Dioxide; D005947:Glucose; D010100:Oxygen