[Response of the coronary arteries to cold test and flow velocity increase is improved by deferoxamine but not by L-arginine in diabetic patients].
Acetylcholine produces coronary artery (CA) constriction in diabetic patients suggesting an impairment of endothelium-dependent dilation. To examine the mechanism of this abnormal response. 2 physiological tests, i.e. cold pressor test (CPT) and coronary flow-increase induced by 10 mg papaverine (PAP) injection in the distal left anterior descending CA (dLAD), were performed before (1) and after (2) either i.v. L-arginine (L-arg, 625 mg/min x 10 min) or i.v. desferrioxamine (DFX, 50 mg/min x 10 min) in 15 normotensive nonsmoker diabetic patients with angiographically normal CA and normal cholesterol. Dimensions of the proximal LAD (pLAD) were measured by quantitative angiography. [table: see text] Before administration of L-arg or DFX, CPT induced a decrease of pLAD diameter, and PAP injection in dLAD dit not modify pLAD diameter. In the 7 diabetic patients receiving L-arg, responses to CPT and PAP were not modified. Conversely in the 10 patients receiving DFX, pLAD dilated in response to the 2 tests. Intracoronary isosorbide dinitrate, an endothelium-independent dilator, produced similar dilation in the 2 groups (+20 +/- 8% and +16 +/- 6%, respectively).


CONCLUSIONS
1) responses of angiography normal CA to CPT and to flow increase are impaired in diabetic patients; 2) abnormal responses are not improved by L-arg suggesting that a deficit in substrate for NO synthesis is not involved; 3) DFX restores a vasodilator response to the 2 tests suggesting that inactivation of NO by superoxide radicals might be partly responsible of the impairment of CA dilatation in diabetic patients.
Nitenberg
A
A
Service de physiologie et d'explorations fonctionnelles, INSERM U 426, hôpital Louis-Mourier, Colombes.
Ledoux
S
S
Attali
J R
JR
Valensi
P
P
D001120:Arginine / Q000494:pharmacology*; D001783:Blood Flow Velocity; D003080:Cold Temperature; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000503:physiopathology; D003331:Coronary Vessels / Q000187:drug effects* / Q000503:physiopathology; D003676:Deferoxamine / Q000494:pharmacology*; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000503:physiopathology; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000096:biosynthesis; D014661:Vasoconstriction; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology*
D014665:Vasodilator Agents; D009569:Nitric Oxide; D001120:Arginine; D003676:Deferoxamine