The mechanisms by which haemoglobin inhibits the relaxation of rabbit aorta induced by nitrovasodilators, nitric oxide, or bovine retractor penis inhibitory factor

摘要: The mechanisms by which haemoglobin and methaemoglobin inhibit the vasodilator actions of glyceryl trinitrate, sodium azide, nitric oxide, bovine retractor penis inhibitory factor (IF) were studied on rabbit endothelium-denuded aortic rings. Methaemoglobin was less effective than against each vasodilator, it more at inhibiting relaxation to azide that trinitrate. Glyceryl trinitrate neither bound nor inactivated when passed through columns haemoglobin-agarose or methaemoglobin-agarose. Azide reversibly but Inhibition is not attributable therefore a direct interaction with haemoproteins, although small part inhibition azide-induced likely be due interaction. Columns methaemoglobin-agarose in removing oxide from solution. greater ability haemoglobin, compared methaemoglobin, vasodilatation induced nitrovasodilators may reflect bind active principle nitrovasodilators. Neither acid-activated inactive forms IF form retained passage haemoglobin-agarose, resulting activity eluates control, unstable and, unlike original activity, decayed rapidly ice. might interact this inactivate it.