Blood pressure response to hyperinsulinemia in salt-sensitive and salt-resistant rats.
We investigated the role of insulin in salt-sensitive hypertension in Dahl salt-sensitive and salt-resistant rats. The rats were kept in metabolic cages, and sodium intake and urinary sodium excretion were measured. In salt-sensitive rats receiving a 0.3% NaCl diet, sodium retention was significantly greater at weeks 1 and 2 in rats that received an insulin infusion than in those receiving a saline infusion. Mean arterial blood pressure and plasma norepinephrine levels were significantly higher at week 3 in insulin-treated rats than in saline-treated rats (mean arterial pressure, 137 +/- 3 mm Hg versus 119 +/- 3 mm Hg, p < 0.05; plasma norepinephrine, 0.40 +/- 0.02 ng/ml versus 0.27 +/- 0.01 ng/ml, p < 0.05). Insulin did not influence sodium retention, mean arterial pressure, or plasma norepinephrine in salt-resistant rats. Coadministration of an alpha-blocker (bunazosin, 10 mg/kg per day for 3 weeks) in salt-sensitive rats abolished the insulin-induced elevations in mean arterial pressure and sodium retention. When salt-sensitive rats were fed a low salt diet (0.03% NaCl), insulin did not raise mean arterial pressure. Thus, insulin elevated blood pressure only in the salt-sensitive model. The sympathetic nervous system and sodium retention in the early phase of insulin overload may contribute to elevation of mean arterial pressure in this model.
Tomiyama
H
H
Department of Cardiology, Surugadai Nihon University Hospital, Tokyo, Japan.
Kushiro
T
T
Abeta
H
H
Kurumatani
H
H
Taguchi
H
H
Kuga
N
N
Saito
F
F
Kobayashi
F
F
Otsuka
Y
Y
Kanmatsuse
K
K
D000818:Animals; D001794:Blood Pressure; D004351:Drug Resistance / Q000235:genetics; D006946:Hyperinsulinism / Q000097:blood / Q000503:physiopathology* / Q000652:urine; D007328:Insulin / Q000097:blood; D008297:Male; D009318:Natriuresis; D009638:Norepinephrine / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D012965:Sodium Chloride / Q000494:pharmacology*
D007328:Insulin; D012965:Sodium Chloride; D009638:Norepinephrine