Effects of streptozotocin-induced diabetes on the pharmacology of rat conduit and resistance intrapulmonary arteries
Poor control of blood glucose in diabetes is known to promote vascular dysfunction and hypertension. Diabetes was recently shown to be linked to an increased prevalence of pulmonary hypertension.
The aim of this study was to determine how the pharmacological reactivity of intrapulmonary arteries is altered in a rat model of diabetes.
Methods: Diabetes was induced in rats by the beta-cell toxin, streptozotocin (STZ, 60 mg/kg), and isolated conduit and resistance intrapulmonary arteries studied 3-4 months later.
Isometric tension responses to the vasoconstrictors phenylephrine, serotonin and PGF2alpha, and the vasodilators carbachol and glyceryl trinitrate, were compared in STZ-treated rats and age-matched controls.
Results: STZ-induced diabetes blunted the maximum response of conduit, but not resistance pulmonary arteries to phenylephrine and serotonin, without a change in pEC50.
Agonist responses were differentially reduced, with serotonin (46% smaller) affected more than phenylephrine (32% smaller) and responses to PGF2alpha unaltered. Vasoconstriction caused by K+-induced depolarisation remained normal in diabetic rats.
Endothelium-dependent dilation to carbachol and endothelium-independent dilation to glyceryl trinitrate were also unaffected.
Conclusions: The small resistance pulmonary arteries are relatively resistant to STZ-induced diabetes.
The impaired constrictor responsiveness of conduit vessels was agonist dependent, suggesting possible loss of receptor expression or function. The observed effects cannot account for pulmonary hypertension in diabetes, rather the impaired reactivity to vasoconstrictors would counteract the development of pulmonary hypertensive disease.
Author: Alison M Gurney and Frank C Howarth
Credits/Source: Cardiovascular Diabetology 2009, 8:4
Published on: 2009-01-21
Copyright by the authors listed above - made available via BioMedCentral (Open Access). Please
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