The role of diabetic vascular alterations in the development of myocardial ischemia.
During the last fifteen years it has become evident that in diabetes there is an increased vasoconstrictor tendency in the arterial bed of different organs. This vasoconstrictor tendency is most expressed in the coronary arteries where sympathetic stimulation exerts vasodilation in the healthy and vasoconstriction in the diabetic arterial bed. Accordingly, myocardial tissue blood flow decreases during hypoxia in the diabetic, whereas it increases in nondiabetic states. Furthermore, 48 hours after ligation of the anterior left descending coronary artery the infarcted myocardial zone was extended below its first major oblique branch in diabetic dogs compared to nondiabetic ones. Since pretreatment with adrenergic antagonists or with cyclooxygenase inhibitors diminished considerably the increased vasoconstrictor tendency in the diabetic state alterations in the endothelium as well as in adrenergic vascular and prostaglandin mechanisms are involved in the pathomechanisms of this phenomenon. Moreover, after mechanical removal of the endothelial layer in coronary arterial strips the maximum force generated by diabetic vessels exceeded the maximum contraction produced by nondiabetic arteries, and the dose-response curve of diabetic arteries to phenylephrine was steeper than in nondiabetic strips. All these phenomena appeared at an early stage when macro- and microscopic alterations could not yet be observed in the vessels. Sodium nitrite or papaverine evoked similar vasodilation in the diabetic and nondiabetic coronary arterial bed.
Pogátsa
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National Institute of Cardiology, Budapest, Hungary.
D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects; D003327:Coronary Disease / Q000209:etiology / Q000503:physiopathology*; D016861:Cyclooxygenase Inhibitors; D003921:Diabetes Mellitus, Experimental / Q000150:complications* / Q000503:physiopathology; D004285:Dogs; D013565:Sympatholytics / Q000494:pharmacology; D014661:Vasoconstriction
D016861:Cyclooxygenase Inhibitors; D013565:Sympatholytics