Effects of streptozotocin-induced diabetes on the pharmacology of rat conduit and resistance intrapulmonary arteries.
BACKGROUND
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 significantly 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.
Gurney
Alison M
AM
Faculty of Life Sciences, University of Manchester, Floor 2, Core Technology Facility, 46 Grafton Street, Manchester, M13 9NT, UK. alison.gurney@manchester.ac.uk
Howarth
Frank C
FC
D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D003925:Diabetic Angiopathies / Q000150:complications / Q000503:physiopathology*; D015237:Dinoprost / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000503:physiopathology; D006976:Hypertension, Pulmonary / Q000209:etiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology; D005996:Nitroglycerin / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects / Q000503:physiopathology*; D011652:Pulmonary Circulation / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000494:pharmacology; D013311:Streptozocin; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D010656:Phenylephrine; D012701:Serotonin; D013311:Streptozocin; D002217:Carbachol; D015237:Dinoprost; D005996:Nitroglycerin; D011188:Potassium