Impaired in vivo venous constriction in conscious obese Zucker rats with metabolic syndrome

The venous system plays a crucial role in regulating cardiac output and blood pressure. Although the relationship between obesity and hypertension is well recognized, little is known about the effect of obesity on venous function. We examined if 16-week-old obese Zucker rats, relative to age-matched...

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Published in:Naunyn-Schmiedeberg's archives of pharmacology 2006-09, Vol.373 (6), p.451-456
Main Authors: Song, Dongzhe, Hutchings, Simon R, Pang, Catherine C Y
Format: Article
Language:English
Subjects:
Animals
Blood Glucose - metabolism
Blood Pressure - physiology
Dose-Response Relationship, Drug
Enzyme Inhibitors - pharmacology
Heart Rate - physiology
Insulin - blood
Male
Metabolic Syndrome - physiopathology
NG-Nitroarginine Methyl Ester - pharmacology
Nitric Oxide Synthase Type III - antagonists & inhibitors
Norepinephrine - pharmacology
Obesity - physiopathology
Rats
Rats, Zucker
Regional Blood Flow - physiology
Triglycerides - blood
Vasoconstriction - physiology
Vasoconstrictor Agents - pharmacology
Veins - physiopathology
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Summary:The venous system plays a crucial role in regulating cardiac output and blood pressure. Although the relationship between obesity and hypertension is well recognized, little is known about the effect of obesity on venous function. We examined if 16-week-old obese Zucker rats, relative to age-matched lean Zucker rats, had altered in vivo venoconstriction to noradrenaline. The obese rats, compared to the controls, had higher mean arterial pressure (MAP), body weight, and plasma insulin and triglycerides, but reduced pressor and mean circulatory filling pressure (MCFP, index of venous tone) responses to noradrenaline (2.5-30x10(-9) mol/kg/min, i.v.). N(G)-nitro-L-arginine methyl ester (L-NAME, 8 mg/kg, i.v., non-selective inhibitor of nitric oxide synthase) did not alter MCFP in either group, but increased MAP of both groups, though the increase was markedly less in the obese than lean rats. Therefore, obese Zucker rats had increased baseline MAP, but impaired in vivo pressor and MCFP responses to noradrenaline, and reduced pressor response to L-NAME. The increased baseline MAP in the obese rats was not due to increased arterial and venous constriction to noradrenaline but rather to reduced influence of the nitric oxide/L-arginine system.
ISSN:0028-1298
1432-1912
DOI:10.1007/s00210-006-0088-8