Responsiveness of vascular alpha1-adrenoceptors of diabetic rat knee joint to phenylephrine in acute inflammation.
In diabetic angiopathy, responsiveness of alphal-adrenoceptors in blood vessels increases. The aim of this study was to investigate the vasoconstrictor response of knee joint blood vessels to phenylephrine (a 1-adrenoceptor agonist) in diabetes and acute inflammation. Acute knee joint inflammation was induced by the intraarticular injection of a 3% kaolin/3% carrageenan suspension. Diabetes was induced by the intravenous injection of alloxan (70 mg/kg). Male albino rats weighing 70 to 90 g each were divided into the following 4 groups: untreated controls, diabetic, inflammatory, and diabetic inflammatory. The blood flow of the knee joint was measured using the laser Doppler flowmetry (LDF) technique. Vasoconstriction of the articular microvascular was measured in response to the topical application of different concentrations (10(-7) to 10(-3) mol) phenylephrine. The results of this study show that (a) increased knee joint diameter and circumference due to inflammation and the knee joint basal blood flow were significantly lower in diabetic than in control rats; (b) the responsiveness of alphal-adrenoceptors decreased in kaolin/carrageenan-induced acute inflammation; (c) carrageenan-induced acute inflammation did not decrease the responsiveness of alphal-adrenoceptors in diabetic rats. We conclude that diabetes inhibits the reductive effect of acute inflammation on the responsiveness of alpha1-adrenoceptors in rats.
Hajizadeh
S
S
Department of Physiology, School of Medical Sciences, Tarbiat Modarres University, Tehran, Iran. HAJIZADS@modares.ac.ir
Shiran
K
K
Fathollahi
Y
Y
D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001168:Arthritis / Q000473:pathology*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism* / Q000473:pathology; D007269:Injections, Intra-Arterial; D007596:Joints / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D008297:Male; D010656:Phenylephrine / Q000008:administration & dosage / Q000494:pharmacology*; D011224:Prazosin / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects*; D012039:Regional Blood Flow / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine; D011224:Prazosin