Hyperinsulinemia superimposed on insulin resistance does not elevate blood pressure.
The role of hyperinsulinemia and insulin resistance in the development of hypertension is an area of much current interest. A central question that remains unanswered is whether exogenous hyperinsulinemia can elevate blood pressure (BP) in the presence of pre-existing insulin resistance. To examine this proposition, we studied the effects of chronic fructose feeding on plasma insulin levels and BP in insulin-resistant Zucker fatty rats and in lean (insulin-sensitive) controls. In addition, vascular responses to norepinephrine in aortae and mesenteric arteries were compared between groups. Zucker fatty rats were hyperinsulinemic, insulin-resistant, yet normotensive when compared with age-matched lean controls. Long term fructose feeding increased plasma insulin levels and BP in the lean group. Strikingly, the fatty rats remained refractory to fructose-induced increases in BP despite exaggeration of hyperinsulinemia. Vascular reactivity assessed in aortae and mesenteric arteries was comparable between groups. These data suggest that, in vivo, the mechanisms of hyperinsulinemia-induced hypertension are not operative in the face of pre-existing insulin resistance in obese Zucker rats.
Verma
S
S
Faculty of Medicine, University of Calgary, Alberta, Canada.
Leung
Y M
YM
Yao
L
L
Battell
M
M
Dumont
A S
AS
McNeill
J H
JH
D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D004195:Disease Models, Animal; D005632:Fructose / Q000009:adverse effects; D006946:Hyperinsulinism / Q000139:chemically induced / Q000503:physiopathology*; D006973:Hypertension / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008638:Mesenteric Arteries / Q000503:physiopathology; D051381:Rats; D011924:Rats, Zucker
D007328:Insulin; D005632:Fructose