High sodium intake enhances insulin-stimulated glucose uptake in rat epididymal adipose tissue.
OBJECTIVE
This study investigated the effect of different sodium content diets on rat adipose tissue carbohydrate metabolism and insulin sensitivity.


METHODS
Male Wistar rats were fed on normal- (0.5% Na(+); NS), high- (3.12% Na(+); HS),or low-sodium (0.06% Na(+); LS) diets for 3, 6, and 9 weeks after weaning. Blood pressure (BP) was measured using a computerized tail-cuff system. An intravenous insulin tolerance test (ivITT) was performed in fasted animals. At the end of each period, rats were killed and blood samples were collected for glucose and insulin determinations. The white adipose tissue (WAT) from abdominal and inguinal subcutaneous (SC) and periepididymal (PE) depots were weighed and processed for adipocyte isolation and measurement of in vitro rates of insulin-stimulated 2-deoxy-D-[(3)H]-glucose uptake (2DGU) and conversion of -[U-(14)C]-glucose into (14)CO(2).


RESULTS
After 6 weeks, HS diet significantly increased the BP, SC and PE WAT masses, PE adipocyte size, and plasma insulin concentration. The sodium dietary content did not influence the whole-body insulin sensitivity. A higher half-maximal effective insulin concentration (EC(50)) from the dose-response curve of 2DGU and an increase in the insulin-stimulated glucose oxidation rate were observed in the isolated PE adipocytes from HS rats.


CONCLUSIONS
The chronic salt overload enhanced the adipocyte insulin sensitivity for glucose uptake and the insulin-induced glucose metabolization, contributing to promote adipocyte hypertrophy and increase the mass of several adipose depots, particularly the PE fat pad.
Fonseca-Alaniz
Miriam H
MH
Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
Takada
Julie
J
Andreotti
Sandra
S
de Campos
Tarcila B F
TB
Campaña
Amanda B
AB
Borges-Silva
Cristina N
CN
Lima
Fabio B
FB
D052438:Adipocytes, White / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D000273:Adipose Tissue / Q000473:pathology; D052436:Adipose Tissue, White / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004822:Epididymis / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D005947:Glucose / Q000378:metabolism* / Q000493:pharmacokinetics; D006339:Heart Rate / Q000187:drug effects; D006984:Hypertrophy; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012982:Sodium, Dietary / Q000494:pharmacology*
D001786:Blood Glucose; D007328:Insulin; D012982:Sodium, Dietary; D005947:Glucose