Inhibition of small-intestinal sugar absorption mediated by sodium orthovanadate Na3VO4 in rats and its mechanisms.
OBJECTIVE
To investigate the inhibitory effects of sodium orthovanadate on small-intestinal glucose and maltose absorption in rats and its mechanism.


METHODS
Normal Wistar rats were lavaged with sodium orthovanadate (16 mg/kg, 4 mg/kg and 1 mg/kg) for 6 d. Blood glucose values were measured after fasting and 0.5, 1, 1.5 and 2 h after glucose and maltose feeding with oxidation-enzyme method. alpha-glucosidase was abstracted from the upper small intestine, and its activity was examined. mRNA expression of alpha-glucosidase and glucose-transporter 2 (GLUT2) in epithelial cells of the small intestine was observed by in situ hybridization.


RESULTS
Sodium orthovanadate could delay the increase of plasma glucose concentration after glucose and maltose loading, area under curve (AUC) in these groups was lower than that in control group. Sodium orthovanadate at dosages of 10 micromol/L, 100 micromol/L and 1000 micromol/L could suppress the activity of alpha-glucosidase in the small intestine of normal rats, with an inhibition rate of 68.18%, 87.22% and 91.91%, respectively. Sodium orthovanadate reduced mRNA expression of alpha-glucosidase and GLUT2 in epithelial cells of small intestine.


CONCLUSIONS
Sodium orthovanadate can reduce and delay the absorption of glucose and maltose. The mechanism may be that it can inhibit the activity and mRNA expression of alpha-glucosidase, as well as mRNA expression of GLUT2 in small intestine.
Ai
Jing
J
Department of Pharmacology, Harbin Medical University, Bio-Pharmaceutical Key Laboratory of Heilongjiang Province-Incubator of State Key Laboratory, Harbin 150086, Heilongjiang Province, China.
Du
Jie
J
Wang
Ning
N
Du
Zhi-Min
ZM
Yang
Bao-Feng
BF
D000818:Animals; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D005947:Glucose / Q000493:pharmacokinetics; D051273:Glucose Transporter Type 2; D007408:Intestinal Absorption / Q000187:drug effects*; D007421:Intestine, Small / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D008320:Maltose / Q000493:pharmacokinetics; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D014638:Vanadates / Q000494:pharmacology*; D000520:alpha-Glucosidases / Q000235:genetics / Q000378:metabolism
D051273:Glucose Transporter Type 2; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; D014638:Vanadates; D008320:Maltose; D000520:alpha-Glucosidases; D000254:Sodium-Potassium-Exchanging ATPase; D005947:Glucose