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EFFECT OF NITRATES AND OTHER CORONARY DILATORS ON LARGE AND SMALL CORONARY VESSELS: AN HYPOTHESIS FOR THE MECHANISM OF ACTION OF NITRATES

1969; American Society for Pharmacology and Experimental Therapeutics; Volume: 168; Issue: 1 Linguagem: Inglês

10.1016/s0022-3565(25)28302-1

1521-0103

Martin M. Winbury, Burton B. Howe, MILDRED A. HEFNER,

Nitric Oxide and Endothelin Effects

Nitrates, such as nitroglycerin and pentaerythritol tetranitrate, produce a prolonged vasodilatation of large coronary arteries but have only a slight transient vasodilator effect on small coronary arteries. The non-nitrate coronary dilators-dipyridamole, prenyl amine, iproveratril, chromonar, lidoflazine, papaverine and aminophylline-have their main action on the small coronary arteries producing vasodilatation. It is concluded that the unique feature of the nitrates is the preferential prolonged vasodilatation of the large coronary vessels, a property not shared with the non-nitrates. As a result of the marked coronary dilator effect, chromonar and dipyridamole interfere with autoregulation. We propose that by dilatation of the large coronary arteries, the nitrates cause a redistibution of the coronary blood supply to areas that are ischemic. The non-nitrate coronary dilators may cause an inappropriate distribution of blood flow, producing an excess in areas where it is not required at the expense of ischemic areas.