Fasting and postprandial plasma concentrations of acylation-stimulation protein (ASP) in lean and obese Pima Indians compared to Caucasians.
OBJECTIVE
ASP stimulates the clearance of free fatty acids (FFA) from the circulation and the synthesis of triglycerides (TG) in adipose tissue. We tested whether fasting and post-prandial plasma ASP concentrations are increased in Pima Indians, a population with a very high prevalence of obesity, but a remarkably low prevalence of dyslipidemia.


METHODS
Plasma concentrations of ASP, TG, FFA, total cholesterol (CHOL), and insulin (INS) were measured in 15 Pima Indians (P) and 15 Caucasians (C) closely matched for age, sex, and body weight [7 lean and 8 obese subjects, body mass index (BMI) cut-off 30 kg/m2], before and for 4 hours after a standard mixed meal (20% of daily caloric requirements, 41% carbohydrate, 44% fat, 15% protein).


RESULTS
Fasting ASP was positively related to percent body fat (dual energy X-ray absorptiometry; r=0.49, p<0.01) and to TG and FFA, independently of percent body fat (partial r = 0.42 and 0.46, respectively, both p<0.05). There were no differences in fasting TG, FFA, CHOL, INS, or ASP between lean C and lean P. In contrast, obese P had lower TG, lower CHOL, higher INS and, on average, 27% lower ASP compared to obese C. The ethnic difference in ASP remained after adjustment for TG, FFA, and percent body fat. ASP decreased in response to the meal in all four groups with no differences between groups. There was a significant inverse correlation between preprandial ASP and the change in FFA 60 minutes after the meal (r=-0.56, p<0.001).


CONCLUSIONS
Pima Indians do not have higher plasma ASP concentrations than Caucasians. Whether other alterations in the ASP-pathway, such as increased sensitivity of adipocytes to ASP, contribute to the high prevalence of obesity and low prevalence of dyslipidemia in Pima Indians, remains to be elucidated.
Weyer
C
C
Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, AZ 85016, USA. cweyer@phx.niddk.nih.gov
Pratley
R E
RE
D000328:Adult; D001055:Apolipoproteins B / Q000097:blood; D001130:Arizona; D001786:Blood Glucose / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism*; D001824:Body Constitution; D015992:Body Mass Index; D002784:Cholesterol / Q000097:blood; D015926:Complement C3a / Q000031:analogs & derivatives*; D005215:Fasting; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005502:Food; D006801:Humans; D006949:Hyperlipidemias / Q000453:epidemiology; D007198:Indians, North American; D008297:Male; D009765:Obesity / Q000097:blood* / Q000453:epidemiology; D014280:Triglycerides / Q000097:blood
D001055:Apolipoproteins B; D001786:Blood Glucose; D001798:Blood Proteins; D005230:Fatty Acids, Nonesterified; D014280:Triglycerides; C044541:complement C3a, des-Arg-(77)-; D015926:Complement C3a; D002784:Cholesterol