Fifty men were selected for the study after recruitment by advertisements. Selection criteria were age 45 to 60 years, absence of diabetes, and a BMI between 25 and 33. A further selection was performed to obtain two groups with different WHR with a division line of WHR = 1.0. Twenty-seven men had a WHR < 1.0, and 23 men had a WHR > 1.0. Four men in each of these subgroups were habitual smokers, and all men were apparently healthy and reported moderate alcohol consumption according to The Alcohol Use Disorders Identification Test (AUDIT).
The men underwent an oral glucose tolerance test (OGTT), stimulation with corticotropin-releasing hormone (CRH) and an arithmetic stress test. Furthermore, diurnal concentrations of adrenocorticotropic hormone (ACTH), cortisol, and growth hormone (GH) were measured. All investigations, except 24-hour hormone profiles, were performed in the overnight-fasting state.
Body weight was measured to the nearest 0.1 kg with the men in underwear, and the height was measured to the nearest 0.5 cm. The waist circumference was measured horizontally midway between the lowest rib and iliac crest, and hip circumference as the widest circumference in the gluteal region. The WHR was then calculated. Sagittal abdominal diameter was determined as the distance between the examination table and the highest point of the abdomen (7). Blood pressures were measured after a 5-minute rest in the supine position with a mercury sphygmomanometer. The average of two measurements with a 1-minute interval was used. Glucose was determined by a commercially available enzymatic method, and serum lipids were measured as described previously (8). Insulin was determined by radioimmunoassay (Phadebas, Amersham Pharmacia Biotech, Uppsala, Sweden).
Profiles (24-hour) of circulating ACTH, cortisol, and GH were obtained from samples collected at 30-minute intervals during 26 hours. The subjects were admitted to the ward between 0900 and 1000 hours. Food was given ad libitum as breakfast (0800 hours), lunch (1200 hours), dinner (1700 hours), and an evening snack (2000 hours). A goal was to have minimal disturbance of sleep, and the men were usually sleeping during the night samplings. Blood samples for analyses of ACTH, cortisol, and GH were collected through an intravenous nonthrombogenic catheter inserted into an antecubital vein. The catheter was connected to a small portable withdrawal pump. Blood was withdrawn at a constant rate and collected in EDTA tubes.
OGTT was performed at 0900 hours with 100 g of glucose dissolved in water ingested within 5 minutes. Blood glucose and plasma insulin were measured via a patent intravenous catheter before and 30, 60, 90, and 120 minutes after glucose administration.
On another morning at 0900 hours, a pituitary stimulation with CRH was performed. An intravenous catheter was inserted, and then the subjects rested for 30 minutes in a recumbent position. At 0900 hours, 100 μg of CRH (Corticorelin [human] as trifluoroacetate, Ferring, Kiel, Germany) was administered intravenously, with the participants remaining comfortably in a recumbent position. Blood samples for ACTH and cortisol were collected 15 minutes before CRH was injected, immediately before and then 15, 30, 60, 90, and 120 minutes after the CRH injection.
An arithmetic stress test was performed as described previously (9). In short, an intravenous catheter was inserted and then the subjects rested for 30 minutes in a recumbent position. During the stress test, which involved forced calculation for 10 minutes, and thereafter, the men were sitting comfortably. Blood pressure and pulse rate were recorded 15 minutes before commencing the stress test, immediately before, and then 10, 20, 30, 40, and 60 minutes after start. Blood samples for ACTH, cortisol, adrenaline, and noradrenaline were drawn at the same points of time (except at 60 minutes).
A dexamethasone suppression test was performed using Salivette (Sarstedt, Rommelsdorf, Germany), which is a sampling device that consists of a small cotton swab inside a centrifugation tube, used to collect saliva (10). The participants were given five Salivettes and one tablet of dexamethasone (Decadron, MSD, Sweden) of 0.5 mg (11). They were asked to chew on the cotton swab during 60 seconds in the morning of each of four days. At 2200 hours on the final day, the dexamethasone tablet was taken. The following morning the salivary sampling was repeated. The decrease in salivary cortisol level after dexamethasone administration was calculated as the mean of the four noninhibited morning values minus the cortisol value the morning after dexamethasone intake.
Total serum testosterone was determined by a nonextraction method where testosterone bound to bovine serum albumin was used as the antigen (testosterone radioimmunoassay; ICN Biomedicals, Costa Mesa, CA). Insulin-like growth factor I (IGF-I) was measured with a non-extraction radioimmunoassay (Nichols, Institute Diagnostics, San Juan Capistrano, CA). ACTH was determined by an immunoassay method (Nichols Institute Diagnostics), cortisol by radioimmunoassay (Orion Diagnostica, Turku, Finland), and GH by a radioimmunochemical method (Amersham Pharmacia Biotech, hGH radioimmunoassay kit, Kabi-Pharmacia, Uppsala, Sweden). Adrenaline and noradrenaline were measured by high-pressure liquid chromatography, and methoxycatecholamines in urine were collected during 24 hours (12).
Comparisons between groups were analyzed with the Mann–Whitney U-test and repeated-measures ANOVA. In Table 2, the Spearman rank correlation coefficient p < 0.05 was considered significant. Data analyses were performed using StatView for Macintosh.
Table 2. Correlations between pulse pressure during stress test and selected variables
|Sagittal abdominal diameter (cm)||0.433||‡|
|Fasting blood glucose (mM)||0.318||†|
|Fasting plasma insulin (mU/liter)||0.433||‡|
|Sum glucose OGTT||0.433||§|
|Methoxycatecholamines (μmol/24-hour urine)||0.255||*|
|Methoxycatecholamines (mmol/mol creatinine)||0.366||†|